Screen Space Ambient Occlusion (SSAO) is used for efficiently approximating the ambient occlusion effect in real-time. Compared to Global Illumination, Ambient Occlusion is less accurate as it only operates in screen space, but it has its advantages. Similar to other post-processing effects like SSR or DOF, it is important that geometries are writing to the Z-Buffer. Otherwise, they won't be affected by this technique. For each pixel, the Screen Space Ambient Occlusion samples the depth values around this pixel and tries to compute the amount of occlusion on this point. 

If your graphic only contains static elements, we recommend to use the Ambient Occlusion option within the Global Illumination features. The quality is much better and more accurate. For any dynamic content, you should use the Screen Space Ambient Occlusion feature. 

Advantages/Disadvantages of Real Time Ambient Occlusion

How to Use Ambient Occlusion

To use Ambient Occlusion, enable it in the Post Processing Effects. This is different from the Ambient Occlusion settings for the Classic Render Pipeline.

SSAO Parameters

• Factor: Controls the strength of this effect.

• Samples: Sets the number of rays used to gather AO information.

• Range: Determines the maximum range of each sample-ray.

• Culling: Determines how much irrelevant AO information surrounding geometry surfaces is discarded.

• Threshold: Determines the threshold to remove artifacts on geometry edges.

• Compensate: Compensates for edge artifacts.

• Blur Kernel: Controls the quality of the blur.

  • K6 - K32: Normal blur kernels that blur the AO in an entire frame.

  • K1 - K2 (Edge-Aware): Bilateral blur kernels that consider geometry edges upon blurring. Performance impact is expected.

• Blur Iterations: Controls how strong the AO gets blurred. This applies only to the Bilateral blur kernels.

• Blur Factor: Controls how strong the AO gets blurred. This applies only to the Normal blur kernels.