HTrace Ambient OcclusionHTrace GTAO vs. URP SSAO
WARNING
The following comparison is performed in the HDRP Demo Scene on a laptop RTX 3060 6GB, 1920 x 1080 native.
Overall Quality
URP's screen-space ambient occlusion appears to be based on the The Alchemy Screen-Space Ambient Obscurance Algorithm rather than any of the known horizon-based approaches. However, it's still closer to HTrace GTAO mode than to SSAO mode, so we will be comparing it against HTrace GTAO.
For the following 2 screenshots, both algorithms were tuned to roughly match in performance and visual appearance in terms of coverage and intensity. URP SSAO severely lacks small and medium scale detail, producing noticeable halo and stripe-like artifacts, and suffers from uneven occlusion.
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Peak Quality
URP SSAO doesn't scale well in terms of tracing and denoising quality. As a result, even when performance or resolution are not limiting factors and higher quality is desired, it isn't always achievable with URP's occlusion. HTrace GTAO offers higher scalability, providing much better visual results.
WARNING
URP SSAO parameters are set to the "High" preset here, while HTrace GTAO uses its medium to high settings.
Resolution Scaling and Upscaling
Unlike URP SSAO, which offers only the Downsample option, HTrace GTAO features 3 different resolution modes: Full, Half, and Quarter, for more fine-grained performance control. On top of that, it provides a sharp and optimized upscaler for interpolating from any of these resolutions to the final target. This makes it more viable to render the effect at a lower resolution and then upscale it, retaining as much detail as possible.
Additional Features
Here is the list of most notable features HTrace GTAO offers that are not present in URP's SSAO implementation: