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We are currently working on integrating OpenColorIO (OCIO) into Terragen. This feature is in closed beta testing. If you're using a version of Terragen with OCIO options we hope you find this page useful. It will be updated as our OCIO features are worked on.


1. Setup OCIO on your computer. If you're working at a company that uses OCIO, this has probably already been done for you. If not, follow the guidelines from the OCIO website. We recommend the "aces_1.0.3" public config. You may need to set some environment variables (at least $OCIO pointing to configuration file).

2. In Terragen, OCIO is enabled or disabled on a per-project basis. If you think of project files as scene file then OCIO is enabled or disabled on per-scene basis. Click on Project Settings at the lower left of the main window, then turn on Use OCIO if it is not already on.

First Tests

Toggling "Use OCIO" in Project Settings should cause the 3D Preview to refresh. If OCIO is configured correctly on your computer then you should also see the colours change in the 3D Preview. The difference may be subtle, but this depends on the OCIO configuration.

When "Use OCIO" is enabled, rendered images should also look slightly different in the Render View. However, at the time of writing (v4.5.00) the Render View does not update when you change this setting; it updates when you start a new render. We are currently working on separating the tone mapping from render time to display time but this is not done yet.

What's Supported in v4.5.00

  • 3D Preview refreshes when toggling OCIO checkbox in Project Settings.
  • HDR renders are interpreted as ROLE_SCENE_LINEAR defined in the OCIO config (e.g. with the ACES config the render is interpreted as ACEScg).
  • LDR/display version of the render is the result of tonemapping and transforming the HDR image using the OCIO config's default view and display settings (e.g. ACEScg -> sRGB).
  • The Render View displays the LDR version of the rendered image (e.g. ACEScg -> sRGB).
  • Saving to an LDR file format (e.g. TIFF) saves the LDR version (e.g. ACEScg -> sRGB).
  • Saving to EXR saves directly from the raw rendered image. Therefore you should interpret EXRs according to ROLE_SCENE_LINEAR in your OCIO config (e.g. ACEScg). We presume this is what you want if you are using Terragen in a multi-app OCIO workflow.

Not Yet Supported

  • Live updates to Render View.
  • Colour space selection in the app. At the moment, Terragen looks at the system-wise OCIO configuration and uses ROLE_SCENE_LINEAR and "default display" to convert from HDR to LDR/display.
  • Conversion of textures and other input colours. Until this is implemented you should expect textures to look different when rendering and viewing with OCIO. You may need to preconvert them.
  • Independent choice of colour space for internal rendering and file output. At the moment, EXRs are output using the scene linear values that were generated by the renderer.

Other Considerations

The default scene -- particularly the default atmosphere -- has colours which were chosen for an sRGB pipeline. They don't know about your OCIO config. If you're using an ACES configuration, for example, you will find that the sky looks too green. We are going to figure out some new defaults for ACEScg, but you might find the following adjusments useful:

"Bluesky horizon colour": reduce the green channel very slightly so that it's closer to the red value than the blue value. "Bluesky density colour" (on the Tweaks tab): increase the red channel so that it's a little closer to the green value.