Hints & Known Limitations

  • Since Radiant GI is a screen-space effect, it cannot use emissive or lighting coming from objects that are not actually visible on the screen in an accurate way unless you enable some of the fallbacks (see dedicated section). When you move the camera around, you can see a fluctuation of the indirect illumination when bright objects leave or enter the camera frustum. This is by design in all techniques based on screen space effects. If this is a problem in your scene, enable one or more fallbacks or reduce the intensity of the effect or disable it completely in that area of your scene (use multiple post processing volumes to adjust it to the requirements of each area if needed).
  • Deferred rendering path is recommended. In this mode, Radiant will use the albedo and specular data from the g-buffers to produce a more accurate result. Forward rendering will still work but the indirect light cast on very dark objects will make them look “whitish”. Use the Luma Influence setting in forward rendering mode to boost dark pixel colors.
  • Performance: a balanced configuration includes the following settings (like the Atrium demo scene):
    1. Indirect Intensity = 1.5.
    2. Ray Count = 1 (increasing ray count is expensive).
    3. Max Distance = 8.
    4. Max Samples = 24 (or lower, then increase jittering to 0.5 or 1).
    5. Thickness = 1.
    6. Binary Search enabled.
    7. Downsampling = 1 (increase to improve performance).
    8. Raytracer Accuracy = 8 (reducing accuracy can improve performance).
    9. Smoothing = 3 or 4 (level 4 can be expensive, try to keep it at 3).
    10. Temporal Reprojection = enabled.
    11. Reuse Rays = 1.
    12. Response Speed = 10
    13. Camera Translation Response = 200
    14. Depth Rejection = 1
    15. Chroma Threshold = 0.25
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