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for my project I have an object on a shadow catcher ground-plane. Now I want to render my object only that casts a shadow onto the ground. The object shall be on a white background while still being in filmic color mode (for HDR reasons).
The reason that this does not work, is because there's no problem with the half-transparency caused by the shadow catcher.
Now my problem: If I composite my scene using the "Alpha over"-node, my background will never be completely white due to the filmic color management. However, if I lay the render over a very high intensity background, the shadow vanished because it's not dark enough to darken down the white.
That way I have the choice between a white background with a just barely visible shadow or a grey background with a visible shadow.
Does anyone have a solution for that problem or am I stuck using the default color management?
Thanks in advance.

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  • $\begingroup$ Not entirely clear. Can you clarify? A shadow is a constricting of light. Light constriction is essentially exposure, which means it is a multiply. It doesn't matter how bright the object is, a shadow will multiply by a normalized amount. This is the same as an alpha channel when operating in a scene referred pipeline, hence why the alpha channel approach works. $\endgroup$ – troy_s Aug 16 '18 at 3:38
  • $\begingroup$ Sorry, that is too much for me :) My problem is that I want a white background in my output png. However, when I crank up the first input in the alpha over node (to a way higher value than 1) to get that white background, the shadow gets less visible since it is being mixed with the over-the-top white, hence it gets brighter. So I have the choice between a white background with a just barely visible shadow or a grey background with a visible shadow. $\endgroup$ – Bastian Springer Aug 17 '18 at 22:46
  • $\begingroup$ You are confusing two models: display referred vs scene referred. You need to revisit your notion of "white". $\endgroup$ – troy_s Aug 18 '18 at 23:33

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