Author Topic: Pure White Background with Shadows  (Read 388 times)

2025-07-25, 21:59:37

shouts25

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Hi everyone,

I’m trying to set up a scene that will produce an image with a solid white (255) background while retaining shadows. I need this to animate and be repeatable with minimal post-processing so it has to happen in the render ideally.

This article seems to work well with colors in the background, but produces a grey background instead of white:
https://support.chaos.com/hc/en-us/articles/4528475679633-How-to-create-an-infinite-background-with-the-Shadow-Catcher-Material-C4D

Other tutorials online use a default c4d sky to achieve a pure white but Maxon seems to have changed the behavior of the sky so it no longer works. I see some discussion on the 3dsMax side where it seems possible, but I cannot get it working in c4d. Is there any solution to this?

2025-07-26, 10:34:42
Reply #1

burnin

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Hi, few things first, to eliminate any further confusion, have you checked:
- Infinite floor/background look? (HDRI Studio Rig look)
- Rendering out with alpha channel that catches the shadow detail
if so, could you then setup a simple exemplary scene and post it here to see what the reality of the issue is (and fix it).
 
&
BTW, this old setup (Re: Shadowcatcher artefacts) appears fine on my side.

PS
It could be Tone mapping, preventing pure white...
« Last Edit: 2025-07-26, 10:49:46 by burnin »

2025-07-26, 11:01:41
Reply #2

romullus

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  • Let's move this topic, shall we?
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It is certainly achievable in 3ds Max and i see no reason why it shoudn't be possible to do the same in C4D. Attaching screenshot of quick setup in Max, hopefully it's somewhat useful to help you to transfer it in Cinema. Short description - plug pure white Corona color shader into Corona tone map control, then into shadow catcher and then into ray switcher. Make sure that exposure, tone mapping and/or LUT are unchecked in tone map control shader and keep in mind that not all tone map control operators can be completely reversed, so you might need to adjust your tone mapping in the VFB if you're not getting pure white background. Ray swither is optional, but without it helps to get more natural illumination of your subject.

Keep in mind that shadow catcher is a special kind of material and how it reacts to shadowing is not very intuitive and possibly physically not very accurate. This is especially evident in edge cases like this, where the background colour is pure white. I wasn't able to get any shadows from HDRI, so had to use Corona lights to illuminate the scene and even with those some tinkering is necessary. In my example two side lights have enabled shadowcatcher illuminator, while the top light has it disabled. You can try different combos to see what works for you, but if all lights have this option either enabled or disabled, they will cast almost no shadows on the shadowcatcher. This limitation only present when background colour is pure white. If you're ok with darker background, then shadows should work just fine, even with HDRIs.
I'm not Corona Team member. Everything i say, is my personal opinion only.
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