Known Issues

Unstable RTAO with TAA enabled (URP)

RTAO mode produces flickering / jittering when Unity's TAA is enabled.

Solution: Increase the Max Ray Bias parameter.

Dynamic Resolution breaks AO (HDRP / URP)

At the current moment Debug views are not guaranteed to scale correctly with Dynamic Resolution. If you notice this issue outside of Debug views as well, try switching Dynamic Resolution to Software mode. URP's Dynamic Resolution is currently not supported. These issues will be addressed in future updates.

Objects leave trails (URP, Forward)

Solution: enable Depth Priming mode in URP Render Data.

Effect isn't visible in build (URP)

This is a known URP shader stripping problem. If URP doesn't detect its own native SSAO render feature, it assumes Ambient Occlusion is not needed at all and strips it from all shaders.

Solution:

• Create a second Universal Renderer Data.

• Add the native SSAO Renderer Feature to it.

• Add this second Renderer Data to the Renderer List in your URP asset.

• Make your original Renderer Data (the one without the SSAO Render Feature) default.

Scene view flickers (BIRP)

Scene view goes black / flickers when HTrace AO is active, but Game view works without issues.

Solution: Make sure you have added the AO script as instructed in the Quick-Start guide. If added directly to camera it will lead to incorrect results.

Occlusion looks worse in the Scene window (URP / BIRP)

In the URP pipeline, temporal accumulation is disabled in the Scene window. This is because Unity only provides valid motion vectors (required for this effect) in the Game window. As a result, GTAO and RTAO, which rely on temporal denoising, will appear worse in the Scene window. Use the Game window to inspect the final appearance of the effect.

Effect isn't working in the Scene window (BIRP)

the BIRP pipeline, ambient occlusion output is disabled in the Scene view. Use the Game view to inspect the effect's appearance

Moving objects flicker in the Scene window (HDRP)

In the HDRP pipeline, Unity does not write object motion vectors in the Scene view. As a result, moving objects may fail to accumulate correct ambient occlusion.

Installation into a project with WSGI overwrites files (HDRP)

In rare cases, trying to import the asset into a project where the HTrace: World Space Global Illumination asset is already installed (and vice versa) may result in a wrong merge / file replacement due to Unity's asset importer issues.

Solution: first unpack the asset to a separate project and then manually copy the folder with the asset to the project where HTrace WSGI is installed.