Author Topic: How to add caustics render element in post?  (Read 455 times)

2020-08-01, 15:55:31

v.p.vlasenko

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The problem is simple - adding CShading_Caustics in photoshop produce completely different result than on raw render.

Doesn't matter which mode I select - the result is different. I tried screen and linear dodge (add), but both at 100% produce too bright (more like atomic explosion) result.

Renders in png 16 format, and working in 16 bit.

Any suggestions?

2020-08-01, 16:41:50
Reply #1

cecofuli

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Remember to disable all tone mapping parameters if you want to obtain the same result in post.

Render in VFB + TONE MAPPING OFF = Composite version


2020-08-01, 18:21:43
Reply #2

v.p.vlasenko

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just tried - nope, not working - results still different.

2020-08-01, 20:48:57
Reply #3

marchik

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as i remember you need to use 32-bit format and "screen" blending mode for the correct result

2020-08-02, 17:17:22
Reply #4

v.p.vlasenko

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No again - there are no screen for 32 bits, add gives wrong result

2020-08-02, 21:49:30
Reply #5

pokoy

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32 bits, exr with 16 or 32 bits floating point, tone mapping off as said above, correct mode is addition. But avoid PS, it doesn't work correctly. Use AE or anything else that actually works in 32 bits.

2020-08-03, 16:04:28
Reply #6

maru

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The correct procedure is to save the beauty element without caustics and the caustics element. Then add caustics on top of beauty using the linear add operation. In Photoshop it is indeed called "Linear dodge (add)".
It is best to use 32-bit EXR.
The image can't have any VFB post-processing enabled (such as highlight compression or contrast).
Exposure adjustments should be fine (it does not matter whether you use EV -1, 0, +1, or any other value).
As mentioned before, it is best to use some proper compositing software rather than PS.