I have a character on the other side of frosted glass in a scene & I want to have her more or less silhouetted. No matter what I've tried though wants to work . I started with turning off lights, then excluding the objects from the lights, then radiosity, etc. and nothing had any effect.

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Only thing I found that would work was to set all the objects (body, hair, dress) of that character to use a matte color of 0,0,0.

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In trying to pick apart what's going on, I used a simple test toroid with just a simple Principled surf, and it responds as expected on either side of the glass when simply excluding the Lights.

Not the case with the character though. When it's not behind the glass, using Unseen by Rays doesn't do anything though even when combined with excluding Lights and Radiosity. What's the difference between Unseen by Radiosity in the Objects Render tab and the Exclude Radiosity in the Lights Tab?

If the figure is behind the glass, and Unseen by Rays is checked, the figure vanishes.

Any suggestions on where to look? It's sounding as if it's a surface issue.