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Global Illumination

This tab contains settings related to global illumination including SSAO (screen-space ambient occlusion), SSGI (screen-space global illumination) and bent normals.

Screen Space Ray-Traced Global Illumination Settings

SSRTGI Parameters

The SSRTGI (Screen-Space Ray-Traced Global Illumination) technology is a set of screen-space ray tracing techniques with real-time performance level. The technology doesn't require light baking, so every object can be freely moved. In other words, SSRTGI is real-time global illumination in the screen space.

The technique implements a real ray-tracing through each pixel of the screen, with a given number of rays and a specified accuracy of obstacle detection (the accuracy is set by using steps). Such ray-tracing is used for Ambient Occlusion (SSAO) to make more realistic shadows between objects, for Bent Normals to smooth ambient lighting on edges, and for SSGI to recreate light reflections from the object's surfaces.

Notice
For the technique to take an effect, the SSRTGI (Screen Space Ray-Traced Global Illumination) feature must be enabled (Rendering -> Features -> SSRTGI).

Ray tracing parameters:

Fast tracing Enables or disables fast tracing for the SSRTGI. This option dynamically changes step size to obtain indirect illumination bounces using low number of steps while keeping performance high. However, tiny objects may be ignored. Disabling this option improves quality, but significantly reduces performance.
Increased accuracy Enables or disables increased accuracy for the SSRTGI. This option reduces visual artifacts by increasing accuracy of the last step.
Resolution Resolution of the SSRTGI. This option significantly affects performance.
  • Quarter - quarter resolution.
  • Half - half resolution (by default).
  • Full - full resolution.
Resolution depth Resolution of the depth buffer used for SSRTGI calculation. This option significantly affects performance.
  • Quarter - quarter resolution (by default).
  • Half - half resolution.
  • Full - full resolution.
Notice
To gain performance this option can be set to lower values while enabling the Increased accuracy option.
Noise step Intensity of the step noise used for SSRTGI calculation. This parameter is used to reduce the banding effect of tracing by using the noise: the higher is the value, the less pronounced is the banding effect.
Noise ray Intensity of the ray noise used for SSRTGI calculation. This parameter is used to reduce the banding effect on the final image by using the noise: the higher is the value, the less pronounced is the banding effect.
Num rays Number of rays of SSRTGI per pixel that are to calculate the final image. Using more rays provides more precise SSRTGI calculation, however, it is more expensive.
Num steps Number of steps of SSRTGI per ray that are used for trace calculation. The higher the value, the more accurate obstacles between objects are accounted. However, this option significantly affects performance.
Step size Size of the trace step used for SSRTGI calculation. The higher the value, the longer the trace. However, tiny objects may be missed. The lower the value, the more detailed will be the tiny objects.
Last update: 2017-12-21