Dear friends, maybe I want a strange thing, but maybe it could be useful for many...
Is it possible to make a plane visible, but not reflecting the light? Or at least reflecting the less amount of light (be not so bright)?
I want a frame with a window to hang in the air. And I want to see the visible part of the frame (marked by the red arrows). An ideal result was made with a Photoshop - picture 1.
But don't want to have a wall visible (picture 2) - it becomes too bright and whole scene becames too bright.
And If I left only frame visible (pic 3), I see it's top and left sides, which are unwanted.
There are several ways of getting the result you want, but if the wall is visible, it reflects light (otherwise it wouldn't be visible!).
But if you for instance give the wall a Holdout Shader, the you can overlay the image over a wall that you like and the light reflected from that wall will not be reflected into the bedroom...