Frequently Asked Questions

Indigo is a software rendering solution.

It is an unbiased raytracer that simulates the physics of light to achieve photorealism from your 3D scenes and models.

Indigo accurately simulates the physics of light which create many realistic effects that otherwise would have to be manually created. Because of this, it takes far less set-up time than traditional biased or 'global illumination' renderers. Simply creating a glass object and a light will produce beautiful caustics.

Effects such as:

* Depth of Field – the depth of field (DOF) is the portion of a scene that appears acceptably sharp in the image.
* Spectral effects – as when a beam of light goes through a prism and a rainbow of colours is produced
* Refraction – as when light enters a pool of water and the objects in the pool seem to be “bent”
* Reflections – from subtle reflections on a polished concrete floor, to the pure reflection of a silvered mirror
* Caustics – as in light that has been focused through a magnifying glass and has made a pattern of brightness on the floor

Physically-based ray tracers need to solve complex equations describing the flow of light within a given scene. These equations are typically solved via a Monte Carlo algorithm, which carefully constructs a randomised process, for which the average outcome is the image we seek.

An unbiased Monte Carlo algorithm is one for which the only source of error comes from statistical variance (which we see in the image as noise).

This means that if you were to render 100 images with an unbiased Monte Carlo algorithm and average them together, it would be a more accurate result. The same is not true for algorithms which are not unbiased, for example Photon Mapping: because the photons have a finite area of effect, illumination details smaller than this cannot be captured, meaning no matter how many images you average together from the same Photon Mapping process, it will not improve details unless you reduce the photon radius to zero (at which stage you have an inefficient path tracing algorithm). Similarly, by enforcing a low number of light "bounces", further rendering will never approach a correct result which takes all the possible light paths into account.

The practical benefit of using an unbiased algorithm is that there are no abstract computer graphics settings to adjust: the process always approaches the most accurate result possible.

Computer processing power becomes cheaper all the time, and because of this the unbiased rendering paradigm becomes more powerful over time too: it is preferable to simply let the computer produce the best possible result directly, than the user spending time trying to find a reasonable compromise.

Currently Revit, SketchUp, Blender, Cinema4D, Maya and 3ds Max are officially supported. Other packages can be used with Indigo by exporting your model as a .dwg or .obj file and importing it into Blender. Blender is a free rendering package.
You must have Indigo installed and an exporter for a 3d package installed to render with Indigo.

If see an exporter that is currently not supported and would like to create one contact Also, see Indigo Technical Reference for technical documentation on how to create your own.

Early (pre 2.0) versions of Indigo were available for free. Indigo became a commercial product in February 2009.

We still offer a free version of the current version of Indigo - but it has these limitations:

* Maximum resolution of 0.7 Megapixels – e.g. 1000 pixels by 700 pixels.
* Indigo logo in the bottom right of the image
* May not be used for commercial work.
* No support (beyond that given in our forums)

You can download the trial and get a feel for Indigo, then purchase a licence from our store and unlock Indigo instantly.

Yes we do have educational pricing. It is valid for students and tutors at high schools, colleges, technical institutes and universities. You can access our educational pricing at:

Glare Technologies Limited is a privately held New Zealand company that develops and supports Indigo Renderer. Glare Technologies Limited was founded in 2008.

Glare Technologies UK Limited is the UK company that currently handles orders and payments.

For more information see the contact us page.


An HDR image is simply an image that holds more colour information than the regular 255 RGB values commonly used. They allow a much greater range of intensity like, for example, the sun and shadow. Monitors are LDR which means the HDR image is compressed and adjusted so that the monitor can display it. HDR images are good for environment maps in Indigo because Indigo can be set to emit light from the environment map based each pixels intensity. This means a sun in the HDR image can be as bright as in real life, and thus cast shadows.
Indigo can read .EXR and .FLOAT file formats for HDR images.

Visit this thread on the forum for many good links for HDR images. HDR 2 EXR + some HDR sites

IES files are the measurement of distribution of light (intensity). Light fixture manufactures often distribute them publicly and can be used to render with.
From HPcipter
Here big pack of IES light from Erco light

Delta light IES profiles in download area:

Rendering with Indigo

Indigo is available at the Ranch Renderfarm.

Because it is an unbiased renderer, Indigo will not tell you when it thinks it is finished. It is up to you to decide when you think the render is clear enough for your purposes. Most renders will give their first image within 30 seconds, but it may take 3/4 hours to give a clear image. Large images (greater than 5 megapixels) may need to be left overnight to become clear.

This is akin to the graininess you get when you take a photo of a dark room with an exposure that is too short. The problem is that not enough light has been simulated to create an accurate representation of the scene. Leave it to render for longer to produce a clear image.

These are called 'fireflies'. They occur when a ray of light randomly reflects into a bright light source, usually the sun. These bright dots also appear in some long exposure digital photography.

There are several settings you can change to reduce fireflies:

* Remove unnecessary glass between the sun and your camera
* Ensure supersampling is set to 3 or 4.
* Set your Rendering mode to Bidirectional with MLT.
* Make sure none of your materials have a color of 1.0, 1.0, 1.0 - all materials should have maximum color values of 0.8, 0.8, 0.8 (no paints in the real world reflect 100% of light)
* Remove the dots using a high pass noise filter in photoshop

When rendering an image, the image is rendered at the specified resolution multiplied by the supersample factor, then reduced for anti-aliasing purposes. The supersampling buffer is also in high dynamic range, so if you are rendering an image of 4000x2000 with a supersampling factor of 4, it will use 384 megabytes of RAM for this buffer.

If you are using a material that has a medium (a specular/glass material), the normals (direction of the mesh faces) must be facing outwards. Also, make sure it is a closed mesh.


4 component JPEGs are usually JPEG files saved by Photoshop in the CMYK colour space.
Support was added for these types of JPEG files in Indigo 3.6.10.
Please update your Indigo version to 3.6.10 or newer:

This is a new xml tag introduced in Indigo 2.4. The error is caused by having an exporter that is 2.4 compliant, but a version of Indigo that is lower than 2.4.
To resolve this error, simply update to the latest version of Indigo. Download

It is likely that Indigo is not installed in the default location.
For SketchUp:
If you do not have Indigo installed at the typical location (Applications), go to Plugins->SkIndigo->Set Indigo Path.
Then, browse to the location of the Indigo application.

This error is caused by two processes trying to use the same network port. Make sure there is not an old Indigo.exe running (check the Task Manager - Ctrl+shift+esc > Processes) before you open a new Indigo process.

This is likely caused by Indigo autosave feature not being able to save at that location due to permissions. To fix this problem, run Indigo as Admin.

Indigo supports loading GIF files since version 3.6.8.
Please install a recent version of Indigo such as 3.6.11:

This PNG file was not correctly saved by the program that created it. Try re-saving it using an image editor such as Photoshop.

Default-meshes.igs is an igs file that contains the mesh information of a scene. It is referenced from a main igs file and cannot be rendered by itself, you must open the main file (either default.igs or a set file-name) to render.
This file is created separately and referenced so that a exporter can export either just mesh data, or all other data without having to rebuild the meshes (which is usually the longest part of an export). This feature is known as "Quick Export".

Look through your material settings, chances are you will have one of your material attributes set to 'shader' with no shader set. If you are trying to use shaders, make sure you refer to the shader documentation in the manual.

This error is caused by the scene requiring more RAM than you have available. Indigo has been tested with scenes up to 30 million unique triangles and creating images bigger than 10 megapixel - but if you do run out of RAM - there are several steps you can take to address this:

Improve your pc:

1. Ensure you are running a 64 bit operating system (32-bit Windows can only allocate 2GB of memory to Indigo)
2. Buy more memory. Indigo works great with 4, 8 or 32GB of ram
3. Don't try and run multiple renders concurrently

Change the scene:

1. Decrease the Supersample factor.
2. Turn off Aperture Diffraction. This feature uses a substantial amount of memory.
3. Decrease the amount of light layers. Each layer contains enough memory for a whole image.
4. Render at a smaller resolution.
5. Downsample the textures you use
6. Simplify the geometry of your scene
7. Use instancing. With instancing Indigo can render literally trillions of triangles in a scene.