I find this very interesting. I have implemented AO myself and understood that its physically inaccurate (it should really be radiosity presence, not ambient occlusion), but have believed the results to look realistic. Or rather; better than flatly lit, which makes geometry hard to understand.
Thank you for these photographs! It would be awesome to have a CG benchmark like this (geometry + light properties) that we could compare to. I'm sure this exists already but. Very neat!
Classic SSAO is very similar to performing an "unsharp mask" based on the depth buffer. This has been proposed "a simple and efficient method to enhance the perceptual quality of images that contain depth information" in the paper "Image Enhancement by Unsharp Masking the Depth Buffer" which came out a year after SSAO was published by Crytek.
https://www.uni-konstanz.de/mmsp/pubsys/publishedFiles/LuCoD...
Nowadays it’s common for SSAO to actually do local radiosity approximation via ray marching. But back in the day when this article was written, that was too expensive so you approximated it by detecting sharp transitions in the depth buffer.
For a benchmark you can just use a "vfx/cinema grade" path-tracing renderer of the same game scene?