Indigo Manual

Principles of physically-based rendering

Image by Lemo

Indigo Renderer delivers photorealistic results through strict adherence to the physics of light. This has some consequences for how the scenes it renders should be modelled, which will be outlined in this section.

Furthermore, the progressive nature of its rendering process means that an image never “finishes rendering” - the image quality improves until you are satisfied with the result and end the rendering process.

Relationship to photography

Rendering with Indigo Renderer is conceptually more similar to photography than it is to using conventional computer graphics applications.

Exporters for Indigo convert the virtual worlds you create in your 3d program into the real world representation used by Indigo.

Units of measurement

Indigo works in units of metres, and your Indigo exporter will export your scene based on the set scene scale – you can work in either metric or imperial.

The use of physical units is crucial in Indigo; for example, window panes should have thickness so that they can properly absorb light as it travels through the glass. If the thickness were specified as 1.2km instead of 1.2cm the glass would appear black, as all the light has been absorbed in travelling through it.

Realistic materials

Image by Camox

Because Indigo is a physically-based renderer, the material properties of objects must be specified in physical terms. Your Indigo exporter will provide the necessary tools and options to allow you to do this in your 3d program. Indigo also comes with the Indigo Material Editor for direct control of materials.

Progressive rendering

Exactly as happens in the real world, Indigo simulates photons emitted from light sources which interact with the scene before entering the camera; the longer a render is left running, the more photons contribute to the final image.

Shorter renders will have a grainy appearance, much like using a high ISO setting and fast shutter time in a real camera. This grain decreases with time: The amount of noise is initially quite high, but very sharply decreases. Eventually a plateau is reached where the image quality is not noticeably improved with further rendering, and rendering can be stopped.

1 second	30 seconds (Scene by Arthur Liebnau)

In general, most people will just leave their scene rendering until it looks clear enough for their purposes. As time goes on, the image will become clearer and clearer.

Image quality, samples per pixel

Indigo measures its render progress as the number of samples that have been calculated. You can imagine these as being the number of “light particles” that have bounced around the scene and hit the sensor in your camera.

Depending on the complexity of your scene, it may take up to 10000 samples per pixel before the image starts to become clear enough for your purpose. Many scenes will start to resolve at around 1000 samples per pixel, and some scenes look good after 100 samples per pixel.

Exporters

It is strongly recommended that you install the main Indigo application before installing any exporters, so that they can find the existing Indigo installation and link to it automatically. (This is normally done for you by the Indigo installer since version 3.2.)

It's possible to have a mismatch between the installed Indigo version and the exporter version; this can result in Indigo displaying an error message about unknown data in the scene file. In this case updating to the latest versions of both will generally resolve the issue.

For more information about the various Indigo exporters, please consult the corresponding manual or our Exporters forum.

Installing Indigo

To download Indigo, go to http://www.indigorenderer.com/download/ and select the appropriate version of Indigo for your platform (Windows, Macintosh or Linux). You should download the latest available version of Indigo, which will be listed at the top of the page.

Toolbar

Many commonly used functions can be accessed from the toolbar for ease of access, and they can also be found in the various program menus.

	Open Scene	Opens a scene in the current window. If a scene is already open, it will be closed (following a prompt).
	Close Scene	Closes the current scene, terminating the current render (following a prompt). Generally you'll want to save your rendered image before closing the scene.
	Render	Start rendering the current scene. Upon pressing this button, the scene will be built and then rendering will start.
	Pause Render	Pauses or resumes the current render, freeing up your computer's CPU for other tasks. You can resume the render at any stage. If you need to run a short, processor-intensive task while rendering, pausing and then resuming the render is effective (Indigo gives itself below normal priority by default, so this is normally not a problem).
	Stop Render	This stops the current render, freeing the used CPU and memory resources for the currently rendering scene. You can still tone-map and save the rendered image after the render has been stopped, but unlike with Pause, you can't easily resume rendering (see Resuming a render if you need to stop and later resume a render).
	Update Image	Indigo only updates the displayed image occasionally, to avoid wasting processing power on image updates which show little visible difference. However, you can at any time press the Update Image button (or the F5 shortcut key) to force an image update.
	Save Image	Once a rendered image is displayed, you can click Save Image to save it to disk in a number of standard formats such as PNG or JPEG, as well as the special Indigo Image (IGI) format for resuming the render later; the PNG format is recommended since it doesn't degrade the image quality as JPEG does.
	Network Rendering	Enables network rendering. See the Network Rendering section for more information.
	Options	Opens the options dialog. See the Options Dialog section for more information.
	Licensing	Use this button to open the Licensing window. You can use this to buy an Indigo licence, immediately removing the restrictions of the free version. See the Licensing section for more information.
	Pick Material	This tool allows you to select a material by clicking on an object in the image view, whose currently applied material appears in the property editor.
	Assign Material	This tool allows you to apply the currently selected material (in the scene view) to an object in the image view by clicking on it.
	Add Material	Creates a new material in the scene view.
	Add Medium	Creates a new medium in the scene view.
	Upload Material	When editing a material, it uploads the material applied to the preview object together with the currently rendered preview image. The preview must be sufficiently clean (at least 200 samples per pixel) otherwise the upload will not succeed.
	Online Material Database	Accesses the Indigo online material database, allowing you to download materials into your scene and the local material database.

Render Settings

The render settings are only visible when a scene is open. There are several sub-sections selectable from the drop down control; these are documented in the following manual sections.

Resuming a Render

While Indigo is rendering a scene, you can save the HDR buffer into an Indigo Image (file extension .IGI) to resume rendering later.

The Indigo Image stores all the information about a render in progress, so if the same scene is loaded again later (even after the rendering has been stopped and Indigo closed), the current rendering state can be fully restored using the IGI file.

To resume rendering a scene using a saved IGI, follow these steps:

Saving the render progress to an IGI

1. Start rendering the scene.
2. In the menu under "Render" click "Save IGI for resuming"
3. Select the Indigo Image file type in the Save File dialog.
4. Choose a file name for your IGI file, for example "test.igi", and click Save.
5. You can now close Indigo.

Resuming

1. When you wish to resume your render, open Indigo, and select "Resume Render from IGI" from the File menu.
2. You will be prompted to locate the IGI file. Navigate to where you saved the IGI file, and press the "Open" button after selecting it.
3. Indigo will read the location of the original scene file from the IGI. If it is no longer present, you will then be prompted to locate the original scene file, which the saved IGI was made with.

   The IGI doesn't store information about the actual scene to be rendered (i.e. models and textures), only about the state of rendering it, so the scene file is still necessary to carry on rendering. You must open the same scene that you were rendering when you saved the IGI.

4. You can confirm that the render resumed successfully by looking at the status bar – the time elapsed should include all the time spent rendering before the IGI was saved.

Indigo File Types

Indigo has several of its own file types for use specifically with Indigo.

Options Dialog

Options Dialog

The options dialog holds settings for the Indigo user interface and rendering options, networking configuration and OpenGL / input controls.

We'll cover these sections sequentially, corresponding to tabs in the options dialog:

1. Interface and Render

   

   • Ask before quitting - Prompts the user for confirmation before exiting Indigo.
   • Ask before closing scene - Prompts the user for confirmation before closing scenes.
   • Default scrollwheel behaviour - By default, when scrolling the mouse wheel over a control which can itself scroll, it will scroll the contents instead of the parent window. When this option is unchecked, it instead scrolls over the control in the parent window without transferring focus.
   • Theme - Changes the appearance of the Indigo user interface according to a selection of pre-defined themes.
   • Information overlay - Displays information about the render in a small black rectangle in the bottom left corner of the image.
   • Watermark - Displays an Indigo watermark in the bottom right corner of the image. Cannot be disabled in trial / unlicensed mode.
   • Image save period - Automatically saves the image periodically, according to how many seconds are specified in the input field.
   • Save Indigo Image - When automatically saving images, this option toggles whether or not a full Indigo Image is saved (rather than only a normal PNG).

2. Network

   

   • Use network manager - Specifies that Indigo's network rendering should be coordinated by a Network Manager instead of running independently.
   • Network manager hostname - The network computer name for the network manager; this cannot be "localhost" or "127.0.0.1" since the name is passed on to other computers, which will incorrectly try to connect to themselves, instead of the particular computer on which it was specified. Other computer names or IPs are valid.
   • Use floating licence - Specifies that Indigo's licensing system should attempt to use a network floating licence instead of the normal per-computer licensing system.
   • Do master search broadcast - If this option is enabled, Indigo will periodically search the local area network (LAN) for Indigo masters wanting rendering slaves.

3. OpenGL and Controls

   

   • Render with textures - Specifies whether the OpenGL preview should use texture maps from the scene. This uses extra GPU memory and increases scene loading time.
   • Maximum texture resolution - Specifies the maximum width or height of textures used in the OpenGL preview. This is useful for reducing the amount of additional memory used by the OpenGL preview.
   • Render wireframes - When enabled, the OpenGL preview shows the scene polygons using wireframe rendering, which can be useful to see the geometric detail in a model.
   • Mouse sensitivity - The slider position specifies how fast the camera will rotate, pan or zoom when in real-time mode; further to the left means less sensitive, further to the right means more sensitive.
   • Invert Y axis - If this option is enabled, mouse movement on the vertical (Y) axis will be inverted, i.e. moving the mouse up will make the camera look down.

4. Image Saving

   

   • JPEG Image Quality - Controls the quality setting for JPEG images saved by Indigo.
   • EXR Bit Depth - Allows you to set the bit depth of saved EXR files.
   • EXR Compression method - Choose the compression method used by when saving EXR files.
   • Combine Layers and Channels into single file - When enabled, layers and channels are combined into a single EXR file, when disabled, Layers and Channels are saved separately to files suffixed with the layer/channel name.

5. OpenCL (GPU)

   

   • Show CPU devices - When enabled, CPU devices are listed and available for OpenCL rendering.

Realtime camera control

Indigo's ability to dynamically edit scene data allows for realtime camera movement, which is very useful for final tweaking of a shot, or simply exploring the scene with full lighting.

There are two ways to effect realtime camera changes: via the on-screen buttons, and via keyboard and mouse controls.

Using the on-screen buttons

To use the on-screen buttons, click and drag on the buttons in the top-right corner of the main render and OpenGL preview windows:

	Rotate	Rotates the camera's view direction.
	Pan	Pans the camera.
	Dolly	Moves the camera forwards and backwards along the view direction.

Using the keyboard and mouse

In the main render or OpenGL preview window:

Holding the Shift key while performing these actions reduces the mouse sensitivity, for more fine-grained control.

Mouse sensitivity and inversion options can found in the Options dialog, in the "OpenGL and Controls" tab.

Automatic Slave

Indigo for Windows has the ability to install itself as a system service, which enables your computer to run a Network Slave during screensaver. This is useful for utilising idle office workstations to accelerate network renders.

To enable the Windows service, navigate to your Indigo installation directory and run the "network_client_service_manager.exe" application, and click the "Install Service" button.

Uninstalling the service can also be done from this dialog, by clicking the "Uninstall Service" button.

Once the service is installed, when the computer goes into screensaver mode, it will start an Indigo Slave and contribute to any active network renders. When the computer exits the screensaver, the rendering is halted to free up the computer for use.

Network Manager

The Network Manager does two things:

1. Floating Licences

   If you have purchased floating Indigo licences, the Network Manager hands out floating licences to computers on your network. However, you don't require floating licences to use the Network Manager for network rendering coordination.

   To purchase Indigo floating licences, email us at sales@indigorenderer.com

2. Managing Network Rendering

   Indigo supports network rendering, which means that additional computers (slaves) can help other computers (masters) render an Indigo scene.

   The Network Manager can control and coordinate this network rendering, by assigning slaves to masters. This is ideal for an office or render farm situation where there are multiple masters and multiple slaves on the same network.

Network Rendering Tutorial

This tutorial will cover network rendering with the Indigo Network Manager.

Set up the network manager

1. Choose the manager computer

   Choose a computer to run the network manager on. Ideally this computer would be running at all times, essentially acting as a server; we will call this computer the "Manager computer".

2. Install Indigo on the Manager computer

   Install Indigo on the Manager computer. For detailed information about this step please see the Installing Indigo section.

3. Obtain the Manager computer's hostname

   A hostname is a name used to identify a device connected to a computer network. To find the hostname of the Manager computer:

   On Windows: From the Start menu, right click on "Computer" and select "Properties". The hostname is listed as the "Full computer name", which is "pixel" in this example:

   

   On Mac: The hostname is listed as "Computer Name" under System Properties → Sharing:

   

4. Run the network manager

   Run the Network Manager on the manager computer. If the operating system prompts for permission to allow incoming connections, answer "Yes". Without this permission, other nodes will not be able to communicate with the Manager computer.

   On Windows: Start → All Programs → Indigo Renderer → Indigo Network Manager
   On Mac: Finder → Applications → Indigo.app → Indigo Network Manager

5. Running a slave

   On another computer that has Indigo installed:

   1. Start Indigo and click on the "Options" button.
   2. In the Network tab, make sure the "Use network manager" option is checked.
   3. In the "Network manager hostname" field, enter the Manager computer hostname.
   4. Ensure that the "Do master search broadcast" option is unchecked.
   5. Click "OK" to save the changes and exit the options dialog.
   6. From the tools menu, select "Start Network Slave".

   Leave the network slave running for now.

6. Running the master

   On the computer that you wish to use as the master computer, e.g. the computer that you will be starting a render from, start Indigo:
   Start → All Programs →Indigo Renderer → Indigo Renderer

   1. Click on the "Options" button.
   2. Ensure that the "Use network manager" option is checked.
   3. In the "Network manager hostname" field, enter the Manager computer hostname.
   4. Ensure that the "Do master search broadcast" option is unchecked.
   5. Click "OK" to save the changes and exit the options dialog.

   Warning: When setting up the master, using "localhost" or "127.0.0.1" as the hostname for the network manager will prevent other slaves from connecting to the master.
   This is due to to the fact that the master will then connect to the network manager through the loopback interface and the network manager will pass the IP from which the master connected on to the slaves. For loopback, this is always 127.0.0.1.

7. Start the render

   On the master computer, open a scene in Indigo that you wish to render, and press the "Render" button.
   Now click the "Network Rendering" button to enable network rendering.

Verifying network rendering is working from the Master

On the Master computer, select "Network Rendering" from the drop down box in the Render Settings view.

If the network rendering configuration is correctly set up, there should be a client listed (with IP address and the hostname) in the "Connected slaves" list:

It will also show the rendering speed in samples per second for each slave. Note that this speed is not known until the first frame is transferred from the slave to the master, and so will show "Unknown" initially.

Verifying network rendering is working from the Network Manager

The Network Manager should show one slave in the "Slaves" list, and one master in the "Masters" list.
Additionally, the "Assigned master ID" for the slave should be the ID of the master. This means that the Network Manager has assigned the slave to the master.

Render Tutorial

In this tutorial we will render an example scene that comes with Indigo to illustrate the basic render settings.

1. Start Indigo and click the Open button in the toolbar. Browse to the "testscenes" subdirectory in your Indigo Renderer installation, which on Windows is usually C:\Program Files\Indigo Renderer\testscenes.
   
   Open the "Caterpillar" example; this scene, by Paha Shabanov, showcases a number of Indigo's more complex features (e.g. displacement, subsurface scattering) and won a competition held on our Forum to be included with the Indigo distribution.
2. This scene renders quite slowly using the default Bi-directional Path Tracing render mode, so let's set it to use the simpler, non-Bi-directional (i.e. single-directional) path tracing mode.
   
   In the Render Settings view (on the right side of the image), from the drop-down menu at the top, select the "Render Settings". From the "Render mode" drop-down, select "Path tracing".
3. Now we're ready to begin rendering. Hit the "Render" button on the toolbar, and Indigo will begin "building" the scene (preparing it for rendering).
   
   For simple scenes, this build process will be nearly instantaneous, but for larger scenes (with many polygons, subdivision surfaces etc.), building the scene can take a little while. Indigo displays the build progress in the status bar, and you can see the full log by clicking the "Render Log" drop-down option from the Render Settings view.
4. Once the scene has started rendering, the status bar will continually update with information about the render in progress.
   
   Particularly relevant is the number of samples per pixel, which can be roughly thought of as the image quality; every so often (with decreasing frequency) the image will automatically update as it's rendering. You can update the image at any time either via the Update Image toolbar button or by pressing F5.
5. After some minutes of rendering the "noise" (or graininess) in the image will go away, leaving a nice clean render:
   
   
6. Next we'll illustrate some of the imaging settings; these affect the appearance of the final image from the physical light computation Indigo performs, and can be adjusted without restarting the render.
   
   In the Render Settings view, select "Imaging" from the drop-down at the top. The default setting for this scene is Camera tone mapping with the FP2900Z preset, and we can change its exposure (EV) and film ISO as with a real camera. If we switch the method to "Reinhard", Prescale to 2 and Burn to 3.6, we get the following result with less saturation, but also less "blow out" in the bright regions:
   
   
7. In the White Point section we see that the scene's default white point is the "E" preset. Typically we use a D65 ("daylight") white point, and selecting this option produces a noticeably "warmer" image:
   
   
8. Finally, let's save this image to disk; click the "Save Image" button in the toolbar, and either give the image a new file name or leave it as is.
   
   Saving as PNG is generally recommended instead of JPEG unless the image will be directly uploaded to the Internet and needs to be compressed, since every time a JPEG image is saved the image quality is reduced (as it is a "lossy" format, as opposed to PNG which is "lossless" i.e. a perfect copy).

Denoising

Since Indigo 4.4.1 beta, Indigo has integrated Intel's Open Image Denoise.

Optimising for denoising

The denoiser requires some additional information to work at maximum effectiveness - in particular it requires the normals and albedo render channels to be enabled.

This can easily be accomplished by checking the 'Optimise for Denoising' checkbox:

Checking or unchecking this checkbox will restart the render.

Enabling or Disabling denoising

Denoising can be enabled or disabled during rendering with the 'Denoise' checkbox. Checking or unchecking this checkbox won't restart the render.

Denoising is computed each time the image is updated and displayed.

Denoising takes some time to compute - especially for high resolution images, and high supersampling factors.

If it is taking too long, try reducing the supersampling factor (for example to 2 or 1).

More denoising examples

A render without denoising. The room scene by Lal-O is included in the Indigo distributon.

The render with denoising.

Environment Settings

There are several options that allow you to define the appearance of empty space around your scene. This listing is not exhaustive, since any material can be used as the background material, however we'll most list the commonly used settings here.

Constant colour background

Illuminates scene with a uniform environment light.

Sun & sky

Indigo comes with a Sun and Sky environment that realistically depicts the sky. Changing the sun's direction creates time-of-day effects: a low angle creates a sunrise/sunset with correctly coloured sky and brightness.

The classic Sun & Sky model.

The following options are available for the classic model:

Turbidity: The turbidity defines the haziness/clearness of the sky. Lower turbidity means a clearer sky. Should be set to something between 2 and ~5.
Extra Atmospheric: Removes the sky and renders only the sun. Good for renders in space.

Since Indigo 3.2, there is also a new "captured" sky model, which is actually simulated by Indigo and captured to disk with the distribution.

The captured Sun & Sky model.

Environment map

Illuminates scene with an environment map, which usually is a high dynamic range (HDR) image.

Indigo can load HDR environment maps in three formats, EXR (file extension .exr), RGBE (file extension .hdr) and a raw data format (extension .float, a simple format exported by the HDR Shop program); the environment map must either be in spherical format or equarectangular.

There are a number of setting available currently for environment maps. The emission values should usually be quite high, approximately 10^7 to be similar to the sun's brightness. The "Advanced Mode" checkbox ticked gives the users more options (full control over the image including Gamma and Texture Mapping modes), while disabling it reveals easy to use controls for rotating and tinting the environment map.

GPU Rendering Guide

GPU drivers

The first and most important point is: you must update your GPU drivers.

GPU compute depends very strongly on the quality of GPU drivers, and the various GPU manufacturers have been doing a great job of updating their drivers to be faster and more robust.

NVIDIA driver downloads: http://www.nvidia.com/drivers
AMD driver downloads: http://support.amd.com/en-us/download
Intel driver downloads: https://downloadcenter.intel.com/

Recommended GPU specifications

NVIDIA

GTX 660 Ti or better
Quadro K4000 or better

AMD

Radeon HD 7770 or better
FirePro W5000 or better

Older graphics cards might work with OpenCL rendering, but may cause problems and are unlikely to provide any significant performance gain compared to Indigo's highly optimised CPU rendering.

Memory limitations

One of the major limitations for GPU-based rendering is the amount of onboard memory available, which is typically 2-4 GB for desktop GPUs, while CPUs can easily have 32 GB. Because of this, you might run out of memory when trying to render scenes with lots of geometry and high resolution textures.

The Max Individual Allocation reported by Indigo is the largest amount of memory that can be allocated at once with OpenCL, e.g. for textures. Indigo performs multiple allocations for every scene. The practical limitation at this point is that the total texture size is limited to 25% of total GPU memory on NVIDIA, and about 65% of total GPU memory on AMD.

Using the computer while rendering

A well-known side effect of using your primary GPUs (ones which are connected to a display) while rendering is that your operating system can lag quite substantially. The best way around this is to have a GPU dedicated for display (usually a small inexpensive card, or perhaps the integrated GPU of some CPUs), while the others are dedicated for rendering. This also helps to reduce the memory overhead, which can be important in GPUs with <= 2 GB of memory running high resolution desktop and lots of web browser tabs etc.

Kernel compilation

Indigo uses a combination of OpenCL and our own programming language, Winter, for the rendering core. This means that when you start rendering a scene, the GPU drivers must compile the OpenCL code, and this process can take some time, depending on the complexity of the scene.

When using multiple GPUs, the kernel builds for each GPU are done in parallel to make better use of the CPU cores, however most GPU drivers do not do multi-core compiling themselves, so future driver updates could improve this without any changes in Indigo.

We are working on making kernel builds faster and less frequent.

Lightmap baking

Lightmap baking

Indigo 4.4.10 introduced a lightmap baking feature.

Lightmap baking is the rendering of a lightmap. A lightmap is an image map that represents the light (or in particular, the irradiance) at points on the surface of an object. Lightmaps are usually used for realtime 3d rendering, for example in computer games or VR experiences.

Lightmap baking in Indigo allows a lightmap to be computed with full unbiased physically-based spectral rendering with global illumination.

A lightmap baked in Indigo

The lightmap used in a realtime OpenGL 3d engine.

UV unwrapping

Lightmaps require a special UV mapping, generally in which each piece of geometry appears just one in the UV map, and there are no overlaps. The process of generating such a UV map is called UV unwrapping.

Indigo can optionally perform this UV unwrapping process, or it can use an existing UV mapping present in the mesh data.

How to use lightmap baking in Indigo

To perform lightmap baking with Indigo, you will need to either enable lightmap baking in the render settings user interface, or alternatively edit your scene file.

To enable in the user interface, select an object in the 'Object to bake' box:

You should check 'Generate lightmap UVs' unless you know your object mesh already has a suitable UV map.

You can alternatively edit your scene file (.igs file, which is just XML), and set the following render settings in your <renderer_settings> element: (see https://www.indigorenderer.com/indigo-technical-reference/indigo-scene-f...)

light_map_baking_ob_uid
If set to a valid UID (>= 0), Indigo will compute a lightmap for the object with the given UID.
type: int
default value: -1

generate_lightmap_uvs
If set to true, Indigo will generate a UV mapping for the mesh that it is computing lightmaps for, if any (see light_map_baking_ob_uid). The new UV mapping will be added to the mesh after the existing UV mappings.
For example, if the mesh has a single UV mapping with index 0, then a new UV mapping will be created with index 1.
The modified mesh with the additional UV mapping will be saved to disk at 'mesh_with_lightmap_uvs.igmesh' in the Indigo Renderer application data dir. (e.g. C:\Users\xx\AppData\Roaming\Indigo Renderer)

If generate_lightmap_uvs is false, then the UV mapping with the highest index in the mesh will be used as the lightmap UV mapping.
type: boolean
default value: false

capture_direct_sun_illum
This option only has an effect when computing a lightmap.
If set to false, direct illumination from the sun will not be captured in the light map. This is useful in the case that direct sun illumination will be rendered using some other technique at runtime, for example shadow mapping.
type: boolean
default value: true

A lightmap with capture_direct_sun_illum set to false; compare with the lightmap above.

Saving your lightmap

Indigo renders lightmaps much like usual renders with a simulated camera. As such you can save the lightmap in the standard ways, including with the Save Image toolbar button, which saves tonemapped, LDR image. You can also save out a HDR un-tonemapped EXR, with the Render > Save un-tonemapped image command.

Denoising

Indigo's integrated denoiser also works very effectively with lightmaps. You can enable denoising by checking the 'Denoise' button in the Image Settings controls in the Render Settings area.

Lightmap without denoising

Lightmap with denoising (same render time)

Object Settings

There are some settings that apply to individual objects. (sometimes referred to as instances)

Please read on for details.

Region rendering

Region rendering allows you to render only a small part of the scene. This is similar to moving the camera, but is useful when you need to focus the render on a part of the full image.

As of version 4, Indigo lets you render multiple regions sequentially and/or simultaneously. There is also an option to either render the region(s) on top of the full image buffer, or on an alpha background outside the regions for compositing in post production software.

Using render regions

To use region rendering, simply enable the "Pick Region" button from the tool bar. This will enable Region Render under Imaging settings, and will let you select your region by using LMB + drag. To render multiple regions at once, hold Shift or Ctrl and drag.

To render your regions on an alpha background, enable the "Zero alpha outside region" checkbox below the Region Render one. This option can be enabled and disabled without re-rendering.

Unchecking the Region Render checkbox will disable region rendering and render the full image buffer. Rechecking Region Render will use your previously used region(s). Camera movement will also disable region rendering for easier maneuvering.

Multiple regions

Zero alpha outside region

Render Channels

Render channels allow extra information to be rendered from the scene.

Beauty render channels are components of the final 'beauty' render, where each render channel captures all the light from a particular class of path from the emitter to the camera.

Non-beauty render channels allow additional information (usually geometric information) to be generated, such as depth, normals, position, or material and object masks.

Support for Render Channels

Render channel support was introduced in Indigo Renderer 4.2.

Render channel support is available in Indigo Renderer, but not in Indigo RT.

Enabling Render Channels

Render channels can be enabled or disabled in the Render Channels page in the Render Settings widget:

Render channel settings.

Note that enabling or disabling a channel will restart the render if it is rendering.

Viewing Render Channels

To change which render channel is shown in the Indigo user interface, you can use the drop-down box above the render display:

Select render channel to display.

Only enabled render channels will be available in the drop-down box.

Saving Render Channels

You can save the render channels to disk with the Save Layers and Channels menu command in the Render menu.

Save Layers and Channels Menu command.

Combine into single file option

This option can be found in the Indigo Options dialog (Tools > Options), in the Image Saving tab.

If enabled, all light layers and enabled render channels are combined into a single EXR file when saving with the Save Layers and Channels menu command.

If disabled, then one EXR file is saved for each light layer and for each enabled render channel. The filenames will have the channel name as a suffix, for example render_channel_test_depth.exr, render_channel_test_normals.exr etc..

Render Queue and Animation

Indigo has built-in animation and render queue support, thanks to the Indigo Queue (.igq) format. Render queues integrate smoothly with network rendering, which means you can use all the computers on your network to render an animation or set of images more quickly.

Render Queue

A Render Queue enables rendering a sequence of frames, Indigo scene files, with full control over the rendering process and halt settings for the different frames.

Creating a Render Queue

When exporting an animation from one of Indigo's 3D modelling package plugins, the Render Queue and an Indigo Queue file is created automatically.

When loading a scene from inside the Indigo GUI, only a single item is added to the render queue, however multiple scenes can be added using the Add Scene(s) button, with a halting condition (on rendering time, samples per pixel or both) to specify how long they should render for. To change halt conditions for multiple frames, simply shift click to select the desired frames, or use ctrl - A (cmd-A on Mac OS X) to select all of them, then change the values to your liking. When changing output paths for the rendered frames, you can use '%frame', which will be replaced with the frame index (0001, 0002, etc.).

Overrides

As of version 4, Indigo has override capabilities for all render settings. This enables the user to change parameters like resolution, render method and clamping for all frames in an animation or sequence. To change a setting, use the controls on the right of the setting. To use the new setting for the other frames as well - simply tick the "Override" tick-box on the left.

Indigo Queue and Packed Indigo Queue formats

To save an Render Queue, go to File -> Save Queue. You can then choose between an Indigo Queue (.igq) format and a Packed Indigo Queue format.

• The Indigo Queue option saves the Render Queue data by itself and doesn't include any scene data.
• The Packed Indigo Queue is a self-contained archive with everything needed to render a sequence of scenes, including all referenced scenes, models and textures etc and with paths made relative. It can be unzipped with compression programs such as 7-Zip. This is the preferred format for distributing Indigo animations.

Opening either of these files in Indigo will add the referenced scene files to the Render Queue window.

Render Settings

This section documents the render settings available in Indigo. Some of these settings may not be exposed directly, depending on which modelling package you're using.

Render mode

Specifies the render modes Indigo should use to render the scene.

If you are unsure which to use, bi-directional path tracing is recommended. See also the render mode guide.

Foreground alpha

Renders and outputs PNG or EXR images with an alpha channel. The background are rendered completely transparent, whereas reflections and absorption in glass will show up semi-transparently in the render as expected.

Clamp contributions

Contribution clamping basically works as a firefly filter.

If enabled, and the max contribution is low, it won't allow bright spots (fireflies) onto the render.
As the max contribution gets higher and higher, brighter and brighter spots are allowed. Max contribution of infinity corresponds to contribution clamping being disabled.

Please note that, since it is clamping bright spots, it introduces bias into the render. Because of this it will be off by default. However it's a useful tool for artists, to remove fireflies from their images in a simple and efficient way.

Halt time

The number of seconds for which Indigo should render, after which the rendering is halted.

Halt SPP

The number of samples per pixel (SPP) Indigo should render to, before rendering is halted.

Network rendering

If network rendering is enabled, other computers on the network will assist in rendering the scene.

Normally the master computer also contributes in this process, however with the working master option disabled only the connected slave nodes will contribute to the rendering (leaving more resources available on the master).

Save un-tone mapped EXR

An un-tone mapped EXR image is saved in the renders directory.

Save tone mapped EXR

A tone mapped EXR image is saved in the renders directory.

Save IGI

An un-tone mapped Indigo Image (.IGI) file is saved in the renders directory.

Image save period

How often, in seconds, the rendered image(s) will be saved to the renders directory.

Super sample factor

Super sampling helps to eliminate hard edges and fireflies in the render, at the cost of additional memory (RAM).

The amount of additional memory required to store the rendered image is proportional to the square of the super sample factor, i.e. for a factor of 2, 4x more memory is required, and for a factor of 3, 9x more memory is required. Note that this does not affect the size of the final image, and does not affect the rendering speed much (as long as the additional memory required is available).

Watermark

If this is enabled, an Indigo logo is displayed on the bottom-right corner of the output render. This behaviour cannot be changed in the Free version of Indigo.

Info overlay

If this is enabled, a line of text is drawn on the bottom of each render with various rendering statistics and the version of Indigo it was rendered with.

Aperture diffraction

Selects whether aperture diffraction should be used. Please see the aperture diffraction documentation for more information.

Render region

Specifies a subset of the image to be rendered; useful for quick previews in complex scenes.

Render alpha

A render mode that sets the pixel alpha (opacity) based on if the pixel is considered to be in the scene foreground or background.

This allows you to composite your rendered image onto another image (such as a photographed background) in an image editing application. See Foreground Alpha.

Lens shift

Normally the lens is located in front of the middle of the sensor, however lens shifting allows you to move it. This is used to compensate for perspective effects when rendering with a relatively wide field of view.

Advanced render settings

Typically users will not have to change any of these settings. Changing these from their defaults can lead to unexpected results and we recommended leaving them at their defaults.

MNCR

MNCR stands for Max Number of Consecutive Rejections, a parameter used in the MLT rendering modes. A lower number can reduce "fireflies", but will introduce some bias into the render.

Auto choose num threads

Automatically chooses all available CPU cores for rendering. Turn this off to manually specify number of threads to use for rendering, in conjunction with the "num threads" option below.

Num threads

Define the number of threads for Indigo to render with.

Logging

If true, a log from the console output is written to log.txt in the current working directory.

Cache trees

If true, k-D trees and BVH data structures are saved to disk after construction, in the tree_cache directory. If the

Splat filter

Controls the filter used for splatting contributions to the image buffer. Either "fastbox" or "radial" are recommended; radial produces slightly higher quality images, but is blurry when used with a super-sampling factor of 1 (a factor of 2 or higher avoids this problem and delivers very high image quality).

Downsize filter

Controls the filter used for downsizing super-sampled images. Only used when super sample factor is greater than 1. The same filters used for splatting can be used for the downsize filter, with a few extra options (please consult the technical reference for more information).

Camera

Indigo implements a physically-based camera model which automatically simulates real-world phenomena such as depth of field (often abbreviated as DoF), vignetting and aperture diffraction.

This is a crucial component for Indigo's "virtual photography" paradigm, as it allows the user to use familiar settings from their camera in producing realistic renderings of their 3D scenes.

Aperture radius

Defines the radius of the camera aperture.

A smaller aperture radius corresponds to a higher f-number. For more information on this relationship please see the excellent Wikipedia page on f-numbers.

Focus distance

The distance in front of the camera at which objects will be in focus.

Aspect ratio

Should be set to the image width divided by the image height.

Sensor width

Width of the sensor element of the camera. A reasonable default is 0.036 (36mm). Determines the field of view (often abbreviated as FoV), together with the lens sensor distance.

Lens sensor distance

Distance from the camera sensor to the camera lens. A reasonable default is 0.02 (20mm).

White balance

Sets the white balance of the camera. See White Balance.

Exposure duration

Sets the duration for which the camera's aperture is open. The longer the exposure duration, the brighter the image registered by the sensor.

Autofocus

When this option is enabled Indigo will perform an autofocus adjustment before rendering, automatically adjusting the focal distance based on the distance of objects in front of the camera.

Obstacle map

An obstacle map texture is used when calculating the diffraction though the camera aperture, to change the way the aperture diffraction appears.

Aperture shape

This allows a particular shape of camera aperture to be specified.

The allowable shapes are "circular", "generated" or "image". A preview of the final aperture shape will be saved in Indigo's working directory as "aperture_preview.png". An image aperture shape must be in PNG format and square with power-of-two dimensions of at least 512 x 512. The image is interpreted as a grey-scale image with the white portions being transparent and black being solid.

For further information and example images please see the aperture diffraction sub-section.

Indigo Manual > Rendering with Indigo > Camera

Tone mapping

Tone mapping changes the brightness and contrast of your image. It can be done at any stage during the render process. Changes to tone mapping will be applied immediately to the rendered image. Tone mapping is non-destructive, so you can play around with the different tone mapping settings without permanently effecting the rendered image. You may want to tone map your image using different settings, and press Save Image to save out several different images.

How it works: Indigo creates a high dynamic range (HDR) image as it renders, and during the tone mapping process this will be converted to a low dynamic range red, green and blue image that can be displayed on your computer monitor. When subsequently saving the image, the user can choose to either save the tone mapped image in JPG, PNG, TIFF or EXR format. Indigo also supports saving of the un-tone mapped HDR image in EXR format for external tone mapping.

Tone mapping method comparisons

Indigo has four different tone mapping techniques that you can choose from: Reinhard, Linear, Camera and Filmic. Here are some comparisons of the different methods, and their strengths and weaknesses, using example scenes from Zalevskiy and Zom-B respectively.

Note how the Camera tone mapping method gives the image a more photographic look with higher contrast and a slight colour tint.

Reinhard is the simplest to use, but once mastered, camera tone mapping can give a nice artistic feel to the renders.

The Filmic tone mapper does a good job with achieving a bright look without burning out the whites.

Linear

The simplest tone mapping method, linear depends on just a single number. Every pixel in the HDR image will be multiplied by this number.

Reinhard

Reinhard is a method based on a paper by Reinhard, Stark, Shirley and Ferwerda from the University of Utah. It is an easy to use tone mapping technique because it automatically adjusts to the amount of light in the scene. It can be tricky to get linear or camera tone mapping to look balanced in scenes where there is an extremely bright light source – the Reinhard method is a good choice for scenes like this.

The default Reinhard settings of prescale=6, postscale=1, burn=2 will give good results for most renders. If you want to adjust the Reinhard method, below is an approximate description of each parameter.

Prescale	Similar to a contrast control, works by increasing the amount of light in the HDR buffer.
Postscale	Works like a brightness control, increases the absolute brightness of the image after it has been tone mapped.
Burn	Specifies the brightness that will be mapped to full white in the final image. Can be thought of as gamma control.

Camera

Camera tone mapping simulates the working of a photographer's camera. You adjust the exposure and ISO settings as you would in a real camera to modify the tone mapping.
The parameters you modify are:

ISO	The ISO number represents the speed of film that is used. The higher the ISO number, the more light will be collected in the HDR Image. In low light situations, a fast film should be used, such as ISO 1600, and in bright lighting situations, a slow film can be used, such as ISO 100.
EV	The exposure value can range from -20 to +20 and represents a correction factor that is applied to the collected light. The higher the EV, the brighter the final image will be. Increasing the EV by one will make the image twice as bright.

The final parameter is the response function. This specifies the type of film or digital camera to emulate. Different films and cameras emphasise different colours. The response functions are taken from real cameras – for example the images below use Ektachrome 100CD film which is famous for being used by National Geographic in their older photos.

A good default for sunny well-lit scenes is an ISO of 200 and an EV of -5.0.

Here are previews of each of the Camera Response Functions

Page 1	Page 2	Page 3

Filmic

Like Linear, this tone mapper has only one control, scale, but it responds quite differently compared to Linear with significantly less contrast at high scale values. This makes it particularly suitable for creating bright images while (to an extent) preventing highlights to burn out.

Render Mode Guide

The different render modes in Indigo each have their own strengths and weaknesses. Different render modes perform differently on different scenes - some render modes will produce less noise, and some render modes will produce more. Since Indigo is an unbiased renderer, all render modes will eventually produce the same resulting render however.

See the Render mode description page for more information on the various render modes.

In this section we will demonstrate the effect different render modes have on a couple of scenes. All images have been rendered for two minutes on a single computer.

The first scene shown here is an 'easy' scene: although there is a small light source, all materials are diffuse.

All render modes perform adequately on this scene, although the non-MLT modes (path tracing and bidirectional path tracing) perform better than the MLT modes.

This shows that MLT is not helpful on 'easy' scenes.

Path tracing render mode

Bidirectional path tracing

Path tracing with MLT

Bidirectional path tracing with MLT

The second scene shown here is the same scene as before, except that the diffuse material on the sphere has been replaced with a specular material. The combination of a small, bright, light source and a specular material make this scene a 'hard' scene.

The path tracing render mode struggles, producing 'fireflies' (white dots) over the image.
(These white dots are not errors, they are just 'noise' in the image, that will go away after a long enough render time)

Path tracing render mode

The bidirectional path tracing mode does much better. There are still some fireflies on the sphere. These are from the notoriously difficult 'specular-diffuse-specular' paths that are a problem for unbiased renderers.

Bidirectional path tracing

Path tracing with MLT 'smears-out' the fireflies produced with the path tracing render mode. However the result is still not great.

Path tracing with MLT

Bidirectional path tracing with MLT is the most robust render mode in Indigo, as it performs adequately even in 'hard' scenes such as this one. There are still some smudges / splotches in this image, but they will smooth out after longer rendering.

Bidirectional path tracing with MLT

Render mode description

Indigo is a ray tracer, which means that it renders scenes by firing out rays and letting them bounce around a scene to form ray paths. Different render modes control the way ray paths are constructed. Different render modes have different strengths and weaknesses for different kinds of scenes.

The main render modes are:

• Path tracing
• Bidirectional path tracing
• Path tracing with Metropolis Light Transport (MLT)
• Bidirectional path tracing with MLT

Generally, bidirectional path tracing should be used as it is the best all-round solution.

Metropolis light transport (MLT) can help rendering speeds in tricky scenes, such as scenes with small lights and glass panes, or sunlight reflected off glass or polished surfaces. See this page for more information about MLT.

Here is a diagram describing what they do:

There are also other, more specialised, rendering modes available for use in post-production:

	Shadows Only shadow catcher materials are rendered to an alpha layer, ready for compositing. Shadows render mode is Indigo Renderer only and is not available in Indigo RT.

Material database

The online material database is a shared repository where users can view, download and share Indigo materials. These are distributed as either .IGM (Indigo Material) or .PIGM (Packed Indigo Material) files, the latter being preferred since it automatically packages all required textures.

Tutorials

• SketchUp: Using the material database from SketchUp

Loading a material into the Indigo Material Editor

The first step is to download the material. To do this, click on the material thumbnail to go the material information page, for example http://www.indigorenderer.com/materials/materials/11.

Then click the download button above the material image. This will save an IGM or PIGM file to your computer.

Now click on the downloaded IGM or PIGM file. This should load the material into the Indigo Material editor and start rendering a preview of it.

Uploading a material to the database

The Upload Material button in the toolbar will upload the material applied to the preview object together with the currently rendered preview image. The preview must be sufficiently clean (at least 200 samples per pixel) otherwise the upload will not succeed.

An alternative way to upload materias is through the Indigo website by hovering over Materials in the section bar, then clicking Upload a material.

Materials

Accurately modelling the appearance of materials in a scene is crucial to obtaining a realistic rendered image. Indigo features a number of different material types, each customisable with various attributes, allowing great flexibility in material creation.

The material previews have been rendered in the main Indigo application (File -> New Material) using the default material ball scene.

Indigo Manual > Rendering with Indigo > Materials

Material Types

This section covers the various material types available in Indigo.

There are also video tutorials available for editing materials within Indigo, which include explanations of the material types, available here.

Indigo Manual > Rendering with Indigo > Materials > Material Types

Diffuse

Diffuse materials are used for rough or "matte" surfaces which don't have a shiny appearance, such as paper or matte wall paint.

Attributes:
Albedo
Bump
Displacement
Base Emission
Emission
Layer

Indigo Manual > Rendering with Indigo > Materials > Material Types

Phong

The Phong material is a generalisation of the Diffuse material type, adding a glossy coating on top of the diffuse base (or "substrate"). The influence of this coating is controlled by its index of refraction (IOR), with higher values corresponding to a stronger specular reflection. (the default IOR is 1.5)

It is commonly used for materials such as polished wooden floors, car paints (when multiple Phong materials are blended together) and metals.

Metals in particular can be represented using either the "specular reflectivity" option (which allows a specular colour to be defined for the material), or via measured material data (referred to as NK data).

IOR (Index Of Refraction): Controls the influence of the glossy coating; higher values produce a stronger specular reflection. The IOR should be set to the real-world value for the material, if available.
For example, the IOR of plastics is around 1.5 to 1.6.
Oil paint binder has an IOR of around 1.5.

Phong material with IOR 1.2

Phong material with IOR 1.5

Phong material with IOR 2.5

NK data: The Indigo distribution comes with a set of lab-measured data for various metals. If one of these data sets is selected, the diffuse colour and specular reflectivity colour attributes are ignored.

Specular reflectivity colour: When not using NK data, this allows you to set a basic colour for the metal; this is useful for uncommonly coloured metals such as Christmas decorations.

Green specular colour	Au (gold) NK dataset	Al (aluminium) NK dataset

Attributes:
Albedo
Bump
Displacement
Exponent
Base Emission
Emission
Layer

Indigo Manual > Rendering with Indigo > Materials > Material Types

Specular

Specular materials are idealised materials which refract and/or reflect as in classical optics for perfectly smooth or flat surfaces (e.g. mirror-like reflection).

A specular material can either transmit light, as is the case with glass and water for example, or not as is the case with metals. This behaviour is controlled by the material's "Transparent" attribute.

If a specular material transmits light, it will enter an internal medium whose properties define the appearance of the material (such as green glass, which has absorption mainly in the red and blue parts of the spectrum). For more information on this please see the correct glass modelling tutorial.

Transparent: If enabled, it allows light to pass through the material. Otherwise only reflected light is simulated.

Attributes:
Albedo
Bump
Displacement
Base Emission
Emission
Absorption Layer Transmittance
Layer
Internal Medium

Indigo Manual > Rendering with Indigo > Materials > Material Types

Oren-Nayar

Oren-Nayar materials are another generalisation of the basic diffuse material type, except unlike Phong which generalises to shiny surfaces, Oren-Nayar generalises to rougher materials.

The appearance is quite similar to diffuse materials, but with less darkening at grazing angles; this makes it suitable for modelling very rough or porous surfaces such as clay or the moon's surface.

Sigma: Controls the roughness of the material. A higher sigma gives a rougher material with more back-scattering. The default sigma value is 0.3, and values higher than 0.5 primarily cause energy loss / darkening due to strong inter-reflection. A value of 0.0 corresponds exactly to diffuse reflection.

From left to right: Diffuse material, then Oren-Nayar with sigma values 0.0, 0.2, 0.5, 1.0.

Attributes:
Albedo
Bump
Displacement
Base Emission
Emission
Layer

Indigo Manual > Rendering with Indigo > Materials > Material Types

Glossy Transparent

The glossy transparent material is a generalisation of the specular material, to allow non-perfect (i.e. rough) reflection and refraction, via an exponent parameter as with the Phong material.

It is commonly used for materials such frosted glass or even human skin (with a low exponent value).

Attributes:
Exponent
Internal Medium
Absorption Layer Transmittance
Bump
Displacement
Base Emission
Emission
Layer

Indigo Manual > Rendering with Indigo > Materials > Material Types

Diffuse Transmitter

The diffuse transmitter material simulates a very rough transmitting material, which reflects no light back outwards. For this reason it is normally blended with a normal diffuse material to model surfaces such as curtains or lampshades.

It is meant to be used on single-layer geometry, and although it does not have an associated internal medium by default, it is possible to use one.

An example of the diffuse transmitter material on its own.

A blend between diffuse transmitter and normal diffuse materials to simulate the appearance of a curtain.

Attributes:
Albedo
Displacement
Base Emission
Emission
Layer

Indigo Manual > Rendering with Indigo > Materials > Material Types

Blend

The blend material type isn't a material per se, rather it combines two sub-materials using blending factor.

This blending factor is a regular channel, and so can be constant, a texture or an ISL shader, allowing for great flexibility in material creation; a blend material can also use a blend as input, enabling so-called "shading trees" of arbitrary complexity.

Note that it's not possible to blend any combination of null and specular materials, except for the case where two specular materials with the same medium are being combined.

An example blend material from the material database, showing a blend between specular and diffuse materials.

Blend: Controls the amount of each material used. A value of 0 means only Material A is used, a value of 1 means only Material B is used, 0.5 implies a 50/50 blend, etc.

Step Blend: Instead of allowing partial blends, only one of Material A or Material B are selected, depending on whether the blending factor is below or above 0.5, respectively. This is recommended for "cut-out" clipping maps (such as for tree leaves), which produce less noise using this technique.

Indigo Manual > Rendering with Indigo > Materials > Material Types

Exit Portal

When rendering interior scenes, one frequently encounters an efficiency problem where the "portals" through which light can enter the scene from outside (e.g. an open window) are relatively small, making it quite difficult to sample.

Exit portals can greatly improve rendering efficiency in these situations by marking important areas through which light can enter the scene, which Indigo will directly sample to produce valid light carrying paths.

Although it is a material type, exit portals don't have any particular appearance of their own, they simply provide an "open window" through which the background material is seen, and through which it can illuminate the scene.

For more information and example images, please see the SketchUp exit portal tutorial.

Requirements for exit portal usage:

• If any exit portals are present in the scene, then all openings must be covered by exit portals.
• The face normals must face into the interior of the scene.
• The exit portal material should only be applied to one side of a mesh (e.g. a cube), otherwise it will lose its effectiveness.

Indigo Manual > Rendering with Indigo > Materials > Material Types

Coating

The coating material simulates a thin coating of some kind of material over another material. For example, you can create a thin coating of varnish over a metal material.

A coating material over a metal metal

The coating material can also simulate interference, which can give interesting effects when the thickness of the coating varies with position:

A coating material over a metal metal with interference enabled. Coating thickness is controlled with a shader.

Depending on the thickness of the coating, and how the thickness varies over the object (which can be controlled by a shader) you may get a kind of rainbow effect, or the material may just take on just a few colours:

400 nm thick coating showing colours from interference.

A coating can also absorb light, which will result in a tinted colour:

Coating with absorption over a metal material. The red colour comes from the absorption of non-red light as light passes through the coating layer.

Coating material attributes

Absorption

Controls the absorption of light as it travels through the coating layer.

Coating without absorption

Coating with absorption

Thickness

Controls the thickness of the coating layer. In the Indigo graphical user interface, the thickness is given in units of micrometres (μm), or millionths of a metre.

A thicker layer will have stronger absorption.

Coating with absorption, thickness of 100 μm.

Coating with absorption, thickness of 10000 μm.

Interference

If enabled, thin film interference is computed for the coating layer.
The result will be most noticable when the coating layer is on the order of 1 μm thick.

Coating without interference, thickness 0.6 μm.

Coating with interference, thickness 0.6 μm.

Indigo Manual > Rendering with Indigo > Materials > Material Types

Double-Sided Thin

The double-sided thin material is useful for modelling thin objects, such as paper or plant leaves.

The double-sided thin material uses two 'child' materials: the front material and the back material, which are used for the front and back of the surface respectively. This means that you can make, for example, a leaf material where the front uses a different texture from the back.

It is also possible to specify the transmittance colour, which controls how light is absorbed and coloured as it passes through the object.

Render using double-sided thin material by Enslaver

Leaf example

When the leaf is lit from the front, you can see that the leaf colour differs based on if the leaf is front or back side towards the camera: (The leaf on the right has the front/top side towards the camera) The light is behind the camera.

Leaf lit from front

When lit from the back, the leaf looks the same from both the front and the back. This is also what happens with a real leaf (try it!)

Leaf lit from back

The roughness (exponent) of the top can be varied independently of the roughness of the bottom of the leaf.
In this render the leaf on the right is frontside-up, on the left backside-up:

Leaf lit from top

Double-sided Thin Attributes

IOR: This is the index of refraction of the thin slab.

Front material: For light that is reflected diffusely back from the front surface, the front material controls the distribution of such light. Should be diffuse or Oren-Nayar. This material would be, for a leaf example, a diffuse material using the front-side albedo texture of your leaf.

Back material. For light that is reflected diffusely back from the back surface, the back material controls the distribution of such light. Should be diffuse or Oren-Nayar. This material would be, for a leaf example, a diffuse material using the back-side albedo texture of your leaf.

r_f: this is the fraction of light that enters the slab that is reflected back to the side it came from.
A good default value is 0.5

Transmittance: Some light scatters right through the slab and out the other side. The transmittance controls the absorption of such light. This is where you would use, for example, your transmittance map of a leaf.

Front Fresnel scale: A factor that controls the intensity of the specular scattering off the front interface of the slab. Default value is 1.

Back Fresnel scale: A factor that controls the intensity of the specular scattering off the back interface of the slab. Default value is 1.

Front Roughness: Controls the roughness of the front interface of the slab.

Back Roughness: Controls the roughness of the back interface of the slab.

Indigo Manual > Rendering with Indigo > Materials > Material Types

Fabric

The Fabric material is useful for modelling textiles, such as cotton, wool, velvet etc. It is similar to a diffuse material except the edges of the material appear a different colour. This simulates forwards and backscattering due to small hair fibres.

Fabric Material Attributes

Colour: This is the main colour of the fabric. As usual it can be a constant colour, a texture, or a shader.

Roughness: This controls the roughness of the surface. A rougher surface will have a wider sheen 'highlight'.

Roughness = 0.1

Roughness = 0.9

Sheen colour. This is the colour of the sheen. The sheen is generally backscattered light, seen around edges of the objects.
For example, this fabric material uses a red sheen colour:

Sheen weight: This is the strength of the sheen reflection.

Sheen weight = 0.1

Sheen weight = 0.9

Indigo Manual > Rendering with Indigo > Materials > Material Types

Null

The null material is not a normal material type (like the exit portal material), but rather indicates that light should pass straight through it, unaffected in brightness and direction.

This on its own is not very helpful, however when combined with the blend material type it becomes very useful for making "cut-outs" such as leaf edges, which would otherwise highly complex geometry.

An example of the null material on its own.

An example of the null material blended with a Phong metal, using a grating texture as blend map.

def fillWithColour(background_colour):
	for(int x=0; x<W; ++x) {
		for(int y=0; y<H; ++y) {
			drawDot(x, y, dot_colour);
		}
	}

def getColourForPoint(u, v):
	if( the point (u, v) is inside a dot ){
		return dot_colour
	} else {
		return background_colour
	}

<material>
	<name>previewmaterial</name>
	<diffuse>
		<albedo>
			<shader><shader><![CDATA[
def eval(vec3 pos) vec3 :
	if(
		fract(doti(getTexCoords(0))) < 0.5,
		vec3(0.9, 0.0, 0.0), # Red
		vec3(0.2, 0.2, 0.2) # Dark Grey
	)
			]]></shader></shader>
		</albedo>
	</diffuse>
</material>

def eval(vec3 pos) vec3 :
	if(
		fract(doti(getTexCoords(0)) * 10.0) < 0.5,
		vec3(0.9, 0.0, 0.0), # Red
		vec3(0.2, 0.2, 0.2) # Dark Grey
	)

IES Lights

If an IES profile is selected, the distribution of emitted light is specified by the information in the IES profile. This is an easy way to get realistic emission profiles for a given light fixture, without creating a detailed model of the fixture.

Please note that only IES files with vertical angles below 90 degrees are currently supported.

See also the IES tutorial in the Techniques section of this manual.

Some freely available IES profiles are available to download from http://www.indigorenderer.com/dist/ies-profiles.zip

Mesh Settings

There are some settings that control how a triangle mesh is rendered in Indigo - in particular the subdivision and displacement settings. Please read on for details on these.

Indigo Manual > Rendering with Indigo > Mesh Settings

Subdivision

Subdivison off

Subdivison On

Subdivision divides each triangle in the mesh into 4 new triangles, with each subdivision level increasing the number of triangles exponentially. Therefore a large mesh of, say, 1 million triangles becomes 4 million triangles when subdivided only once. When subdivided twice it becomes 16 million triangles, and when subdivided three times it becomes 64 million triangles.

Below are available settings:

View Dependent	Subdivide only meshes visible by the camera
Max Subdivisions	How many times to subdivide the mesh. Polycount becomes exponentially larger with each subdivision level.
Curvature Threshold	Triangles will not be subdivided if their curvature is smaller than this threshold.
Pixel Threshold	Triangles will not be subdivided if they are smaller than this pixel threshold.

Light Layers

Light layers allow you to separate contributions from different lights onto different "layers". Each layer can then be manipulated separately, even after the render has completed.

You can change the brightness of each layer, or change the overall colour of each layer, or even turn each layer off completely.

Enabling Light Layers

By default, all lights in an Indigo scene are assigned to Layer 0. This means that the HDR image will have only one layer – Layer 0. However, in the exporter for your 3D modelling program, you can change the layer that a light is assigned to. All contributions from that light will then be rendered onto that layer.

Each layer has a number of controls that you can manipulate in the Indigo GUI; please see the corresponding section in the Indigo interface section.

Compositing with shadow pass tutorial

Requirements

This tutorial requires Indigo 3.6.19 or newer.

For this tutorial you will need a car model, standing on a single quad:

You will also need a high dynamic-range environment map (in .hdr or .exr format), plus a backplate image. (which are typically in .jpg format)

Preview of background plate from Moofe

Preview of HDR environment map from Moofe

The environment type should be set to Environment Map, and should be using the high dynamic range environment map mentioned.

Making the shadow pass

You will need to set the ground plane to be a shadow catcher material. To do this, first select the ground plane material with the Pick Material button. Then make the ground material be of Diffuse material type.

Then check the Shadow catcher checkbox at the bottom of the material options.

You may also be able to set the shadow catcher material option directly in your exporter.

Then change the render mode to Shadows:

This should produce a render like so:

For best results, you can make the car object invisible. You can do this by selecting the car object(s) with the Pick Object button, then checking the Invisible to camera checkbox, or by setting the Invisible to camera option for the object in your exporter.

This should produce a result like this:

Making the foreground car render

To make the foreground car render, the car object should be visible to the camera.
The ground object should be invisible to the camera - that is, it should have Invisible to camera checked: (Select the ground object with Pick Object to show these settings)

Now set the render mode to a normal rendering mode like Bidirectional path tracing.

Check the Foreground alpha checkbox. This will make only the car have non-zero alpha:

This should produce a render like this:

Compositing the layers together

We now have 3 layers that we want to composite together:

• The background plate
• The shadow pass
• The foreground render

These layers can be easily composited together in a program such as Photoshop or GIMP:

The final result should look something like this:

Credits: Scene setup originally by hcpiter. Background plate and HDR are by Moofe.

Compositing your scene into an environment

Scene with HDR environment map

Often it is not economical to model and create an environment for your scene to sit in, and it is a common technique to composite elements together to fake it.

There are three main techniques for doing this; the first and easiest is to use alpha compositing. The second method, which gives the best results, is to use an environment map, and the third is to use image planes (or "background cards").

Depth of Field

Depth of field is a phenomena that causes certain parts of an image to blur based on its distance from the camera. It is exploited as a photographic technique for a variety of reasons. A shallow depth of field can be used to accentuate certain parts of a scene, give more detailed information about a subject by exposing just a portion of it, or to remove a distracting background. A wide depth of field puts all elements in focus.
An image is always sharpest at the cameras focal distance, but the depth of field is controlled by the camera's aperture, measured in f-stop. The smaller the f-stop number, the smaller the depth of field; the larger the f-stop, the larger the depth of field.

Wide depth of field, f/22

Shallow depth of field, f/2

IES Lights

IES stands for the Illuminating Engineering Society, which has defined a file format for describing the distribution of light from a light source.

Using only a small, simple emitter such as a single quad, an IES profile will shape the distribution of light emitted from it to match that of a much more complicated light fixture, such as in the examples below:

Digital Photometric data. With the basic Indigo profile Left, and an IES profile Right.

While Indigo is capable of creating real refractions of an accurately modelled light fixture to create this effect, it is far easier to use an IES profile, and the result is much the same. Many manufactures provide IES files for their lights, and it is a great way to add realism to your scene.

You can use an IES viewer to preview these profiles. There is a very good viewing program made by Andrey Legotin that can be found here: http://www.photometricviewer.com/

Setting up the scene

Firstly, we will set up a simple scene to show off the light effects. For this I have made a flat ground plane, to catch the light, and a small, single plane mesh above and perpendicular to it.

A single plane mesh raised off the ground

The plane will be our light-source, so select the it and assign it an emitting material in your Indigo plugin. Since we are working with artificial lighting, go to your environment settings and disable the sun and set a black background.
Hit render and you will get the standard Indigo light render like so:

Render with no IES profile

Adding an IES profile

Open the material editor of your Indigo Plugin, under Emitter Attributes you will find the IES path. Download the zip of IES files here http://www.indigorenderer.com/dist/ies-profiles.zip and link to one. Hit render to view the new IES profile in your scene.

Render with IES profile

Note that Indigo does not support IES profiles with a vertical angle of more than 90degrees and will give an error if attempting to do so.

Optimizing your scene

There are many things you can do to make Indigo render your scene faster, and cleaner, often without compromising quality.

Scene Settings

The first thing you can do is make sure the scene you are rendering is suitable for the power your computer offers.

Light Layers

If there are many light layers used, it will consume a lot of memory. If this exhausts all physical memory the rendering will become extremely slow due to disk access. For more information on light layers, see this section of the manual.

Render resolution

A larger screen resolution, and larger Super Sample factor, will take longer to render, simple because there are more pixels to cover. See Imaging Settings

System Requirements

Check the recommended system requirements to see how your computer compares.

Understand your Render mode

Indigo has several render modes, which control how it chooses where to render, and how. Which mode is appropriate to use varies from scene to scene. Scenes with a lot of specular materials, for example, should be rendered with MLT enabled.
See Render Mode.

Scene design

Some things about the way the scene is made can slow a render down, and likewise speed it up.

Over-saturated colours

If a colour (this includes any colours in texture maps) is over-saturated, it creates an unrealistic conservation of energy as light bounces off it. This can create strange artifacts known as 'fire-flies', along with other problems.
Make sure that no colour is more than 80% saturation, which translates to an RGB no higher than that of 204,204,204.

Glass and liquids

Glass and liquids are one of the things that make Indigo renders stand out. However they can be computationally intensive, and therefore it pays to be aware of how they can affect render times.

Try MLT Bi-Directional path-tracing

MLT is good for clearing glass and liquids, and combined with bi-dir it can help those otherwise hard-to-render areas

Glass around a light source

While it is important to model your scenes as they would appear in the real world to realistically render with Indigo, modeling a light bulb as glass around a light source can greatly lengthen render times. This is because every single ray of light that is emitted has to pass through the glass and reflect & refract its way through it. Effectively this means that all light in the scene is now a caustic. Simply giving the light-bulb's outer shape an emitting material will give the same effect as a real light-bulb, without the extra calculations.

Glossy-Transparent

This material is especially difficult to reproduce efficiently, because of the complex effects it creates. It is strongly suggested that this material not be used to transmit the sole light into a room (as a sky-light for example) See Glossy Transparent

Glass Acceleration

This feature allows glass sheets/panes to be rendered extremely effectively. If the scene has sheets or panes of glass, enabling this will reduce your render times. See Render Settings

Physically correct modelling of glass

Glass is realistically simulated in Indigo, as a (transmission) medium, which requires a little more care when modelling scenes compared to "traditional" renderers. In this section we will focus on glass, however the principles covered here extend to other media (such as water, fog, etc).

We begin with a concise statement of the requirements, and then go into some details. The executive summary is:

When modelling glass in a scene, it cannot be represented as a single surface; there must be at least two (for entering and exiting), and the glass medium occupies the space between them. Furthermore, the surface normals in all cases must point outwards.

Let's start with the first part: glass must be represented as a volume. The following diagram illustrates how light interacts with a glass pane:

As light travels through the glass medium, its brightness is diminished; this is what gives glass its colour, and it is physically due to the thickness of the glass (and the medium properties), not a "glass colour" modifier at the surface.

If either of the glass faces are not present, the glass volume becomes infinite (since light cannot exit the medium). For example, rendering a house with single-surface glass panes will result in the interior being essentially black, as the light will have lost most of its energy travelling through several metres of glass.

Now that we have described the problem with single-surface glass, we show how to correctly model glass panes. SketchUp is used here, however the same principles apply to all 3D modelling packages.

The simplest way to correctly model a glass pane, is to take a thin box (e.g. a cube squashed in one dimension) and apply an Indigo glass material to it:

SkIndigo has a default glass material, however if you wish to make your own then you should use the Specular material type with IOR 1.5 and transparency enabled.

Here is the result rendered in Indigo:

The next step is to insert the glass box into the window frame. Note that we make the glass pane bigger than the opening in the window, allowing the glass faces to intersect the frame, so that the medium is perfectly contained without tiny gaps.

If you want to be more efficient about this, you can remove all faces except for the front and back - since these should be contained entirely inside the solid wall, they cannot affect the rendering and can be safely removed.

With the glass inserted to the frame, we obtain the desired result:

Installation

1. Download and install Indigo

   Download Indigo RT or Indigo Renderer for your system and install to the default location on your system.
   You can download Indigo from here: http://www.indigorenderer.com/download/

2. Download and install Indigo for SketchUp (SkIndigo)

   On Windows, the Indigo installer comes bundled with the latest version of SkIndigo, the installer for which should launch from the main Indigo installer.

   Mac users must download the RBZ file and install it manually (since there is no installer for those platforms); the latest version of SkIndigo can be downloaded from http://www.indigorenderer.com/documentation/sketchup.

   Please see https://www.indigorenderer.com/documentation/manual/indigo-sketchup/inst... for instructors on how to install the RBZ file.

3. Check your SkIndigo Installation

   Restart SketchUp after installing SkIndigo and you should see see “SkIndigo” become available under the Plugins menu.

   
   The SkIndigo Plugins menu

   You are now ready to use SkIndigo.

4. Enabling the SkIndigo toolbar

   The SkIndigo toolbar should be enabled by default, however if it is closed, you can re-enable it by right clicking on the toolbar area, and ticking SkIndigo from the context menu.

   

   The SkIndigo toolbar should now be visible:

   

5. Getting help with SkIndigo Installation

   If you have any issues installing SkIndigo, please email us at support@indigorenderer.com.

The Plugins Menu

The Plugins Menu is the primary place to access SkIndigo functionality, open dialogues and start rendering.

Toolbar

After SkIndigo has been installed, a small toolbar is added to the SketchUp user interface for easy access to commonly used export functionality from the menu:

Render with Indigo	Export the SketchUp scene to Indigo format and start rendering it in Indigo.
Render Selected Entities	Export and start rendering only the currently selected entities in your SketchUp scene.
Material Editor	Open the SkIndigo material editor.
Render Settings	Open the SkIndigo render settings dialog.

Right-Click Menu

SkIndigo adds some features to the context-sensitive right-click menu in SketchUp.

Material Editor

This is where you can add the unique Indigo material settings to your objects so they behave realistically. You can find it via: Plugins -> SkIndigo Material Editor. See Indigo Materials for full information.

To work with an Indigo material, simply open up the SkIndigo Material Editor and apply any SketchUp material to an object. The painted material will be selected in the SkIndigo Material Editor. There are other ways to select a material for the SkIndigo Material Editor:

• Use "pick" from the SkIndigo Material Editor
• Select a face and in the right-click context-menu select the name of the material

1. List of Materials

   Here is where all the textures applied in your SketchUp scene are listed, choose the desired one to start creating a material out of it.

2. Main Menu

   Import	Import a Indigo Material (.IGM). Use to bring in materials from the Material Editor.
   Export	Export this material as an IGM or PIGM file which can be opened in the Indigo Material Editor or uploaded to the Indigo Material Database.
   UI	This switches between the simple mode of SkIndigo, and the normal mode (See above). The simple view takes your settings and converts them as best as it can to normal settings. Normal mode is recommended. It is well worth your time to learn the Indigo Material Types as it allows you full control.
   Search	Search the online database and download materials
   Pick	Use a picker tool to select materials

3. Preview Pane

   Shows the current material, the Preview function replaces this with a rendered scene with the material placed on the chosen model (to the right). Make sure you stop the preview when you are finished previewing the material as this can greatly slow down your computer.

4. Material Type

   Select the Material Types from this drop-down list. Each has its own attributes that are listed below. Assign Preset: Choose a preset material from the list provided. This will replace any of the current material settings. See Material Types.

5. Material Attributes

   Here is where the material attributes live. They allow you to add more details to your material. The list will change depending on the Material Type selected. See Material Attributes.

   

   1. List of Material Attributes

   2. Map

      Where the information is sourced from. Depending on which map type is selected, the "..." on the right will open different editors.

      Constant	A constant value.
      SketchUp	Use the SketchUp texture or color.
      Texture	Use an external (non-SketchUp) texture map.
      Shader	Define a material using the Indigo Shader Language (ISL)

   3. Values

      Changes the common value of this attribute. Usually a multiplier.

   4. Map Editor

      There are several editors that will open depending on the map set.

      • SkIndigo Texture Editor

        
        Position Map: First, select any number of faces in your model. Clicking this button will apply this texture to the selected faces so you can then position the texture using the SketchUp texture positioning tools. Once you have positioned the texture, you can save the UV set using the right-click context menu. Be sure to paint the desired material back to the selected faces before rendering.

        See Texture Maps

6. Emitter Attributes

   See Base Emission and Emission

7. Media Attributes

   See Internal Medium

8. Mesh Subdivision

   See Subdivision

Render Settings

The Render Settings Window configures the scene for export to Indigo.
Find it at Plugins > SkIndigo > Render Settings

1. Output

   Image Dimensions	Configures the width and height of the render to be created. Keep in mind that the free version of Indigo can only render images up to 1000x700 pixels in size; you will need to order a licence to use higher resolutions.
   Region Rendering	Region rendering allows you to render only a small part of the scene. This is similar to moving the camera, but is useful when you need to focus the render on a part of the full image.
   Save to .IGI	Saves an IGI file for reach rendered scene. On by default.
   Custom Image Name	Enable this to use a custom name for the PNG image that is automatically saved when rendering.
   Watermark	Enable this to add the Indigo logo to the rendered image. The free version of Indigo will always do this, regardless of this setting.
   Image Name	To use this image name, the Custom Image Name checkbox must be checked.
   Image Path	Renders will be auto-saved to this directory.
   Thumbnail Path	Material preview images will be saved to this directory.
   Auto-Save Period	Enter the time interval in seconds that the rendered image will be saved.

2. Camera

   See Camera

3. Tonemapping

   See Tonemapping

4. Environment

   See Environment

5. Advanced

   See Indigo Render Settings

SkIndigo Tutorial

This tutorial goes over generating a simple scene and lighting it a few different ways. The scene will be a typical German apartment with white walls, wood flooring and some furniture from Ikea. We won't be modelling the garage with an Audi, dog called Schatzi and traditional lederhosen.

This tutorial was done for SketchUp 2013 free version; your SketchUp may look slightly different, and basic familiarity with SketchUp (e.g. navigation and selection) is assumed.

Materials

SkIndigo on Windows Tutorial

This tutorial will cover getting Indigo running with Google SketchUp on your computer running Microsoft Windows. We will use the SkIndigo exporter to export scenes from SketchUp to Indigo.

You can use either the free or the commercially licensed Indigo version to follow this tutorial; the free version will add a watermark to the final renders and limit the resolution to 0.7 megapixels.

Step 1: Install SketchUp

If you already have SketchUp installed, you can skip this step.

Download and install SketchUp from here: http://www.sketchup.com/intl/en/download/

Step 2: Download Indigo Renderer

The latest version of Indigo Renderer can be downloaded from this page: http://www.indigorenderer.com/download-indigo-renderer

If you have a 32-bit operating system, or you are not sure, download Indigo Renderer for Windows 32-bit.

If you have a 64-bit operating system, download Indigo Renderer for Windows 64-bit.

Step 3: Install Indigo Renderer

Once you have downloaded the Indigo installer program in Step 2, run the installer program.

If the installer asks you 'Do you want to allow the following program to make changes to this computer,' select 'Yes.' Please carefully read the licence agreement, then click 'I Agree.'

On the 'Choose Components' page, leave all components selected, and press 'Next >'

On the 'Choose Install Location' page, leave the Destination Folder as it is, and press 'Install.'

Press 'Finish'. Indigo will open after installation; close it for now, since we'll be using it via SkIndigo.

Step 4: Open Sketchup

You should now see the new SkIndigo tool bar:

Step 5: Enable extension in SketchUp 2016

In SketchUp 2016 you may need to enable the extension in the preferences.

Select Window > Preferences from the main menu.

Under Extensions, enable SkIndigo.

Step 6: Render with Indigo

Press the 'Render with Indigo' button in the SkIndigo tool bar:

If everything has been installed successfully, Indigo should launch, and start rendering the default scene immediately:

Tutorials

Installation

This sections describes how to Install Indigo for Cinema 4D on your Computer.

Interface

Tutorials

Example Scenes

Here you can find a few example scenes illustrating how to use Indigo for Cinema 4D.

The file contains scene files showing:

• Depth of field
• Exit portals
• Index of refraction
• Materials
• Sub-surface scattering
• Sun and Sky

Download the example scenes. (up to C4D R18)
Download the example scenes. (R19 and up)

Getting started

1. Ensure a supported version of 3ds Max is installed

   A 64-bit version of 3ds Max is required.

2. Download and install Indigo

   Download Indigo for your system here; if you are unsure about which version to download, please see this tutorial page.

   Upon running the installer, ensure that the "3ds Max plugin" component is selected for installation:

   

   Continue with the normal install process for Indigo, after which the Indigo for 3ds Max installer will launch.

3. Install Indigo for 3ds Max

   When the Indigo for 3ds Max installer launches, you will be prompted for the versions of 3ds Max you would like to use with Indigo:

   

   If you encounter any problems installing Indigo for 3ds Max, please email us at support@indigorenderer.com.

4. Verify that Indigo for 3ds Max was correctly installed

   After the Indigo for 3ds Max installer has completed, restart 3ds Max. Enter the Render Setup dialog by pressing F10, and click the "..." button next to the Production renderer entry in the Assign Renderer roll-out:

   

   From the list of renderers, select "Indigo Renderer" :

   

Indigo for 3ds Max is now installed and ready to use.

Basic usage tutorial

This tutorial follows on from the Getting Started guide, and covers the basic rendering and material editing workflow. Basic familiarity with 3ds Max is assumed.

Rendering the basic scene geometry

We begin with an empty 3ds Max scene, and create a teapot on a pedestal as shown:

Before rendering, we must assign Indigo as the active renderer in the Render Setup dialog (keyboard shortcut: F10), as per the Getting Started guide.

If there are no light sources present, which is the case in a newly created scene, IndigoMax will use a sun/sky background to illuminate the scene.

So if we now hit Render, we get an image like this:

Adding Indigo Material light sources

Next we will use our own light sources to illuminate the scene, instead of the default lighting. Lights in Indigo must have finite area, i.e. they cannot be point or directional lights; so we create the simplest possible surface, a quad patch, and point it at the teapot (two lights are shown here, illuminating from the sides):

We must now create a material for this object, to specify an emission parameter. Open the Material Editor window and create a new Indigo Material, which we'll call "emitter".

In the emitter material settings, we'll set a black albedo colour (i.e. our light doesn't reflect any light) and a "white" emission colour:

Adding Phong Indigo Materials

We'll also create two new Indigo Materials for the teapot and the pedestal. Change the teapot material definition to "Phong", then turn it into copper by choosing its chemical name "Cu" from the Complex IOR combo box. For the pedestal material we'll simply choose a dark green colour for the Phong albedo:

If we now apply the emitter material to the two light quads, and the teapot and pedestal materials to their respective models, we get the following rendered result:

Using specular materials

Another important material type is Specular, which simulates perfect reflection and refraction as governed by the physical Fresnel equations to produce realistic glass, water, acrylics etc.

The use of this material type is somewhat more complex than others, since objects with Specular materials must be closed (so as to produce a containing medium). For more information on this please see the manual page on physically-correct glass modelling.

We'll turn the copper teapot material into a glass material by changing its material definition to "Specular / glossy transparent". To give the glass some colour, we sett its transmittance colour to a cyan, and increase the Strength a bit to make it darker / more dense:

To better illustrate the effect of the Specular material we put a while wall behind the teapot and pedestal, and change the pedestal to be made of gold:

Final notes

There is an increased amount of noise in the image, due to the complex light paths which can result from specular light interactions. Indigo's strictly unbiased rendering can have difficulty rendering such scenes cleanly using the normal sampling mode, and for these situations the MLT sampling mode can be of assistance.

HDR illumination is easy to set up, allowing for realistic and efficient illumination from distant light sources, as specified by Indigo Texture maps (illustrated here by the Uffizi Gallery HDR image by Paul Debevec):

This concludes the basic usage tutorial. For more information on using Indigo please refer to the rest of the manual and our Tutorials section, and our Forum contains a wealth of useful information (besides being a great community to interact with!).

IndigoMax configuration settings

IndigoMax supports 4 different basic configurations, or usage modes, to allow for greater workflow flexibility.

These configurations can be selected from the Render Setup menu, in the IndigoMax settings tab:

The 4 configurations work as follows:

• Regular - Renders until the halting time or samples per pixel has been reached. This is the default mode, suitable for rendering animations. To cancel a render, press cancel on the render view.
• Background - Renders continuously, scene changes do not affect the render unless restarted. Not suitable for rendering animations. To stop a render, press the Stop button.
• Interactive - Renders continuously, scene changes (geometry, transforms, materials, cameras) cause the render to restart immediately. Not suitable for rendering animations. To stop a render, press the Stop button.
• Export - Exports a scene to disk (location is specified in the advanced settings tab), and optionally launches the standalone Indigo application to render the scene after export.

Material settings

The Indigo Material in 3ds Max allows you to switch between the various basic material types Indigo supports, specifically Diffuse / Oren-Nayar for rough reflecting materials (e.g. matte paint, chalk), Diffuse transmitter for rough transmitting materials (e.g. lamp shades, curtains), Phong for smooth reflective materials (e.g. metals, plastic) and Specular / glossy transparent for water or glass (both smooth and frosted).

There are also three more complex Indigo material types, which use other Indigo materials as sub-materials: Blend, Coating and Double sided.

Indigo materials can be found in the Indigo Renderer sub-menu when creating materials:

Diffuse / Oren-Nayar

For more information about the Diffuse and Oren-Nayar materials, please click the links to see the relevant documentation pages.

Diffuse material settings:

• Albedo - The material reflectance colour.
• Sigma - The roughness, where 0.0 is perfectly diffuse and 0.3 is very rough. For motion information on this parameter please see the Oren-Nayar documentation.

Diffuse transmitter

For more information about this material type please see the Diffuse transmitter material documentation.

Diffuse material settings:

• Albedo - The material transmittance colour.

Phong

For more information about this material type please see the Phong material documentation.

• Diffuse - The colour of the diffuse base (or substrate).
• IOR - Controls the influence of the glossy coating; higher values produce stronger specular reflection. The IOR should be set to the real-world value for the material, if available; for example, the IOR of plastics is around 1.5 to 1.6, and oil paint binder has an IOR of around 1.5.
• Exponent - The exponent of the Phong specular highlight; larger values (e.g. 1000+) produce sharper highlights, while low values (e.g. 10) are quite rough.
• Complex IOR - Allows you to select from a list of lab-measured metal reflectance data. This overrides the IOR and Diffuse settings.
• Fresnel scale - Allows you to adjust the strength of the Fresnel reflection falloff.

Specular / glossy transparent

For more information about the Specular and Glossy transparent materials, please click the links to see the relevant documentation pages.

• Exponent - The Phong glossy reflection and refraction exponent. Set to a very large value (such as 1 million) for perfect specular / no glossiness.
• IOR - The index of refraction of the medium contained in this material; water has an IOR of ~1.33, diamond ~2.4.
• Precedence - The precedence of the medium inside this material. If there are multiple media occupying the same volume of space (e.g. ice in water in air), the one with highest precedence is used.
• Dispersion - Enables wavelength-dependent refraction (dispersion). Note that this can take significantly longer to converge (tip: use MLT).
• Absorption Strength - Scales the material transmittance colour.
• Transmittance - The material transmittance colour.
• Scattering Strength - Scales the scattering spectrum.
• Scattering Spectrum - Defines the (possibly wavelength-dependent) scattering spectrum. Note that this can take significantly longer to converge (tip: use MLT).
• Phase function - The phase function used to describe scattering in the medium.
• G param - The Henyey-Greenstein G parameter, which specifies the preference for forwards (G > 0), backwards (G < 0) or uniform (G = 0) scattering.

Blend

For more information about the Blend material, please click the link to see the relevant documentation page.

Blend material settings:

• Material A - The first material used for blending.
• Material B - The second material used for blending.
• Blend Amount - A constant blending factor; 1.0 means 100% of Material A is used, 0.0 means 100% of material B is used.
• Step blend - Disables partial blends so the result is either material A or B, depending on whether the blend amount (constant or map) is >= 0.5.
• Texture - Allows you to use a texture map to control blending.

Coating

For more information about the Coating material, please click the link to see the relevant documentation page.

Coating material settings:

• Substrate - The base material which lies underneath the coating.
• Thickness - The coating thickness in millimetres.
• Roughness - Specifies the roughness of the coating, where 0 is perfect specular reflection and 1 is very rough.
• Fresnel scale - Allows you to adjust the strength of the Fresnel reflection falloff.
• IOR - The index of refraction of the coating medium.
• Interference - Enables the simulation of light interference in the coating, works best with thin coatings.

Double-sided

For more information about the Double-sided thin material, please click the link to see the relevant documentation page.

Front and Back material settings:

• Material - The material for the front- or back-facing side.
• Roughness - Specifies the roughness of the material's coating, where 0 is perfect specular reflection and 1 is very rough.
• Fresnel scale - Allows you to adjust the strength of the Fresnel reflection falloff.

• Fraction - The blending fraction between the front and back sides.
• Transmittance - The material transmittance colour.
• IOR - The index of refraction of the coating medium.

Environment settings

The Indigo environment settings can be set from the normal 3ds Max environment settings, allowing a choice of physically-based Sun/sky or environment map illumination in your scene.

For example, to create a Sun/sky environment, open the Environment Settings dialog (keyboard shortcut: 8) and select the Indigo SunSky option from the Indigo Renderer Maps list:

The Indigo Sun/sky and environment map settings are described in the following sections.

Physically-based Sun/sky

Indigo offers two Sun/sky models: either the classical Preetham Shirley Smits model, or the more accurate spectrally simulated model.

• Sky model - Selects the sun and sky model to use; the "classic" model is a standard physically-based sun and sky model, and the captured simulation is the directly simulated sun and sky introduced in Indigo 3.2.
• Sun node - Sets the light source which will act as the sun. This must be specified in order for the sun and sky model to work.
• Sun layer - The light layer index in which the direct sunlight contribution is stored.
• Sky layer - The light layer index in which the skylight contribution is stored.
• Turbidity - A higher turbidity corresponds to more overcast skies. Currently only affects the original sky model.

Image environment map

In this mode, an Indigo Texture (potentially in HDR) can be used as a background map to illuminate the scene. Usually latitude / longitude maps are saved in the compact .EXR format.

• Color - A constant background colour in the given emission units.
• Image - Allows you to specify an Indigo Texture map as an image source. For more information on setting up HDR environment maps, please see the subsection on using image environment maps.
• Intensity - A linear brightness scale factor.
• Exposure - An exponential brightness scale factor.
• Base emission - Allows you to specify a given spectrum map as the basic illumination component, e.g. 6500K blackbody for "white". The Image and Color scale with this base spectral colour.

Blendigo on Windows Tutorial

This tutorial will cover getting Indigo running with Blendigo on your computer. We will use the Blendigo exporter for Blender, that is used to export scenes to Indigo.

This tutorial is for Windows users.

If you have not purchased an Indigo licence, you can still follow this tutorial. Indigo will run in trial mode, which will apply some watermarks to Indigo renders.

Step 1: Install Blender 2.58 or newer

If you already have Blender 2.58 or newer, you can skip this step.

Download and install Blender 2.58 or newer from here: http://www.blender.org/download/get-blender/

Step 2: Download Indigo Renderer

The latest version of Indigo Renderer can be downloaded from this page: http://www.indigorenderer.com/download-indigo-renderer

If you have a 32-bit operating system, or you are not sure, download Indigo Renderer for Windows 32-bit.

If you have a 64-bit operating system, download Indigo Renderer for Windows 64-bit.

Step 3: Install Indigo Renderer

Once you have downloaded the Indigo installer program in step 2, run the installer program.

If the installer asks you 'Do you want to allow the following program to make changes to this computer,' select 'Yes.' Please carefully read the licence agreement, then click 'I Agree.'

On the 'Choose Components' page, make sure that the 'Blender exporter' is selected (otherwise Blender must be reinstalled), and press 'Next >'

On the 'Choose Install Location' page, leave the Destination Folder as it is, and press 'Install.'

After the Indigo installer has completed, the Blendigo installer will launch. It should autodetect where Blender is installed (otherwise Blender must be manually located, or reinstalled):

Press 'Finish'. Indigo will open after installation; close it for now, since we'll be using it via Blendigo.

Step 4: Enable plugin in Blender

Select 'User Preferences' in the editor type selector:

Then select the 'Render' category:

Then make sure the check-box on the right of the 'Render: Blendigo' box is ticked:

Select 'Info' in the editor type selector:

Now set the render engine to Indigo:

You should now be able to render scenes with Indigo by pressing F12.

Installation

1. Getting the latest version of Blendigo

   The Indigo installer comes bundled with the latest version of Blendigo, however it can also be downloaded stand-alone from our Blender sub-forum, where it will be near the top of the top of the listed topics.

   If you choose to use the stand-alone Blendigo installer, please note that you will still need to have the latest version of Indigo installed. For this reason we suggest using the Indigo installer to install Blendigo.

2. Ensuring the correct version of Blender is installed

   Upon running the Blendigo installer, either from the main Indigo installer or the stand-alone installer, it will report the required version of Blender in the title, for example "Blendigo 3.6.25 for Blender 2.69".

   If this version is not installed, install the appropriate version of Blender from http://www.blender.org before continuing.

3. Completing the installation

   After you've verified that you have the appropriate version of Blender installed, allow the Indigo or Blendigo stand-alone installers to complete. If you're using the Indigo installer, ensure that the Blender exporter option was selected and installed.

   As mentioned above, you must have Indigo installed in addition to the Blendigo exporter in order to render with Indigo from Blender. More detailed instruction for installing Indigo can be found here.

   If the installer reports that it cannot find Blender on your system, either point it to your custom installation location, or follow the instructions from Step 1 again and ensure you install to the default locations. If you encounter further issues, please email us at support@indigorender.com.

4. Configuring Blender to use the Blendigo add-on

   Open Blender, and from the File menu select "User Preferences". We want to enable the Blendigo add-on, so we select the "Render" filter from the list on the left near the bottom. Click the checkbox next to the "Render: Blendigo" option; it should become highlighted.

   The dialog should look similar to this:

   

   Click "Save As Default" so you won't have to do this every time you'd like to use Indigo as a renderer for Blender.

5. Setting the correct path to Indigo installation

   You will need to make sure that the correct path to the Indigo executable is set in Blendigo:

   You can find it here (Make sure Indigo is selected as the current render engine first - see next section)

   

   On Windows, the path should be to the directory that the Indigo executable is in.

   On OS X, the path should end with "Indigo.app", not "Indigo.app/Contents/MacOS/".

6. Exporting a simple test scene

   First we must set the current renderer to "Indigo" from the drop-down box at the top of the Blender window (the default being "Blender Render"):

   

   If no lights are present in the scene, as is the case by default, then Blendigo will automatically add a Sun lamp to the scene.

   Press F12 to initiate the export and render process, launching Indigo.

Interface

Blendigo's functionality is tightly integrated into Blender, so the Indigo camera settings are located in the normal Blender camera options, the Indigo material settings are located in the normal Blender material options, etc.

For the most part these Indigo settings correspond exactly to those documented in the corresponding manual section.

Tutorials

Indigo for Revit Tutorial

This tutorial will cover getting Indigo running with Revit on your computer. We will use the Indigo for Revit exporter to export scenes to Indigo for rendering.

If you have not purchased an Indigo licence, you can still follow this tutorial. Indigo will run in trial mode, which will apply some watermarks to Indigo renders.

For this tutorial, we will assume that you have either Revit 2014 or newer installed already.

Step 1: Install Indigo for Revit

Download and run the latest Indigo for Revit 'Free Trial' installer here: http://www.indigorenderer.com/revit

For more detailed information on installing Indigo for Revit, please see the Installation section of this chapter.

Step 2: Rendering with Indigo from Revit

Start Revit and open the Sample Architecture Project.

Due to limitations imposed on Revit plugins, Indigo for Revit cannot be used while in a perspective view. So we must first select a non-3D view from the views list, such as the Site view:

Having changed to a non-perspective view, we can access the Indigo Renderer section from the "Add-ins" menu:

Click on "Edit Render Settings", then in the options dialog select the Living Room view:

Click Ok to save the settings, then click "Render with Indigo". After a brief export process, it should launch Indigo Renderer and begin rendering the scene from the selected view, which should look like this (example from Revit 2014):

Click to enlarge.

Installation

This guide will detail installing Indigo for Revit on your computer. Revit 2014 or newer must be installed first so that the installer can auto-detect the installation location.

The first step in the install process asks you to agree to the Indigo for Revit licence terms. Once you've read this, click the Install button; you will need an account with Administrator privileges to continue.

The first part of the installation process is installing the main Indigo Renderer application, so its installer will launch as part of the overall Indigo for Revit install process.

For more information on installing Indigo, please see the relevant manual section.

Once Indigo has been installed, the Indigo for Revit installer will look for Revit installations and offer to set up the exporter addin for each:

After this has completed, Indigo for Revit will have successfully installed and is ready to be used.

Material Editor

The Material Editor is used to configure the Indigo materials in the scene.

Indigo for Revit will automatically convert your existing Revit materials, however in Revit 2013 this conversion is somewhat limited by available information to plugins. To this end, the material editor allows you to edit the converted materials to make them more lifelike.

Revit 2014 exposes material definitions with lots of additional information compared to previous versions, allowing for a much higher quality conversion. Therefore, Indigo for Revit 2014 does not currently feature a material overriding system.

To create full custom Indigo materials from scratch, use the Indigo Material Editor that comes with your Indigo installation.

The online Indigo Material database is a warehouse for quality user-created materials that can be downloaded and used for free under the Creative Commons Licence. You can find it here: Indigo Material Database

Start by choosing the material type you would like to make, and then adjust the attributes below it. Changing the material type will change the options available.

Most materials have similar material appearance settings, allowing you to specify a single colour or an image map as the basic material colour. Image map is used to link to external texture files. Indigo can use PNG, TIFF, JPG/JPEG, TGA, BMP and EXR file formats. Bump maps add fine details to surfaces without creating more geometry, a great way to add realism.
Sample width specifies the size in mm of the image map , then tile.

See also: Indigo Materials, Material Types, Material Attributes.

Matte

The matte material type models surfaces which reflect light almost equally in all directions, such as wall plaster, clay and other rough materials.

Glossy

This material type can be used for shiny or glossy materials such as plastics, wood, fabrics etc.

Smoothness

You can define how sharp the reflection is by the 'smoothness' slider. 'Rough' gives a matte surface that diffuses the reflection; 'smooth' gives a sharper, glossy reflection.

A rough glossy material	A smooth glossy material

Reflectivity

This value controls how much light is reflected by the surface. Insert values into the reflectivity box for fine control.

Rough with low reflectivity	Rough with high reflectivity

Translucency

Translucency allows light to pass through the material surface and light the opposite side without being transparent or clear. Can be used for thin, coloured plastics, or even thin fabrics like a curtain or lampshade.

Fully Opaque	80% translucent

Metal

The metal material type is used to create metallic surfaces.
You can define how sharp the reflection is using the smoothness slider. 'Rough' gives a matte surface that diffuses the reflection; 'smooth' gives a sharper, glossy reflection.

A rough metal	A smooth metal

Lab-Measured Metals

Indigo comes with accurately measured metal materials that can be found here. They refer to their element names, as given by a Periodic Table.

Gold: Au	Aluminium: Al

Transparent

This is used for any materials through which light can pass e.g. glass, clear plastics or water. Frosted Glass introduces the following extra parameters:

Reflectivity

This value controls how much light is reflected by the surface.

Low reflectivity	High reflectivity

Smoothness

You can define how sharp the reflection is by the 'smoothness' slider. 'Rough' gives a matte surface that diffuses the reflection; 'smooth' gives a sharper, glossy reflection. This attribute is only available for Frosted Glass.

A rough frosted glass	A semi-smooth frosted glass

Render Settings

The Indigo for Revit Render Settings control how Indigo renders your scene.

Here is an example screenshot of the render settings window:

The Camera and Output tab contains options to select which 3D view to render from and the rendered image dimensions. Higher image resolutions will generally take longer and use more memory to render.

The Use network rendering option is useful for automatically starting network renders on export, which use the Indigo Network Manager to handle distributed rendering.

Tone mapping determines how the huge brightness range of real physical scenes gets compressed into the limited range displayable on computer screens; it is worth experimenting with these to get the best result for the particular scene being rendered.

The Environment tab contains options for the lighting environment; this can be either entirely background lighting (via physical sun and sky, or an HDR environment map), or optionally include the illumination from other light sources in the scene.

The Procedural Grass tab allows you to easily add fully 3D grass to your scenes, simply by choosing the material(s) on which grass should be scattered. The drop-down combo box lists the materials in the scene, which can be added to the list of grass scattering materials via the Add button; for example, adding the Grass material with the default settings produces a nice lawn in almost any scene. The view culling option is useful to only create grass in direct view of the camera, which speeds up the scene building before rendering; the grass density (in number of instances per square metre) can also be tweaked.

The Renderer Settings tab contains more advanced options such as options for Metropolis Light Transport. This is an advanced method for computing illumination that enables faster rendering of complex scenes, however it is not recommended for simpler scenes.

Using Indigo for Revit

After installing Indigo for Revit, a tool bar for Indigo Renderer will be added under the Add-Ins menu.

Please note that this menu is inaccessible in perspective views due to Revit plugin limitations.

The Indigo for Revit workflow

To render your scene with Indigo, ensure that you have a 3D camera set up, then hit the Render with Indigo button in the Indigo Renderer addin menu.

The general Indigo for Revit workflow:

1. Create or position a 3D camera to be used for rendering.
2. Edit the Render Settings.
3. If you are using Revit 2013, tweak the materials and their attributes using the Indigo Material Editor. Revit 2014's material system is vastly improved, and no manual tweaking is necessary for accurately converted and beautifully rendered materials.
4. Render with Indigo.