Ambient Occlusion behind Glas

[Schmidhuber]

Hello everyone,

to get AO behind glass I have done 2 renderings so far. One rendering with glass, one without glass. I then used the 2 renderings in Photoshop.

Is it possible to render AO behind glass in one rendering process or is there another possibility?
Thanks for your input

[frankmci]

Internally, Octane considers AO and Refractive Rays as different categories of illumination. Octane Glass/Specular Materials by default allow Refractive Rays to pass, but not Ambient. I suggest you use the Ray Switch node in the Opacity channel of your glass material to make it at least partially transparent to AO rays. Depending on the color/thickness of your glass, you may need to experiment with what value between 0-1 looks correct to your eye.

[Schmidhuber]

Ambient Occlusion should be multiplied in Photoshop as an extra layer.
I hope the pictures make it more understandable - it's about AO behind the glass - not in the glass.

[frankmci]

Ah, I thought you were trying to avoid compositing all together and wanted control of the AO through the glass surface.