Compositing lights and shadows into correctly shaded wall

[Stof]

Hi everyone,

I have been making architectural visualisations for a while and one of the things i do that is a bit unique is i composite the back wall in photoshop instead of taking the base render of the wall...

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This is how i do it:
Take the light selects from lightmix
Light 1
Light 2
Light 3
Source Color (Aka white)

Now do a render of the wall again and do a shadowcatcher for compositing.

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I take thise elements and composite it inside photoshop but it never 100% looks like the real wall if i just rendered it out.. Can anyone figure out what im doing wrong or some element i might be missing?

I have attached an image of the wall that is a normal render and one that is composited.

Thanks in advance :)

[James Vella]

Are you using 'linear dodge add' mode instead of 'screen'?

[Aram Avetisyan]

Hi,

How exactly does the render look like?

And what format are you saving the lightmix layers in? What is the bit depth for them?
And what is the image mode set in Photoshop - 8 bit, 16bit or 32 bit?

Common practice is to save out in, e.g., 16bit EXR format and do the compositing.
But I am not sure what you mean exactly by "to look like the render".

Remember that when changing a color for the backwall, and it is not a RaySwitch material, then its color will affect everything, including the GI.
If what you want to do is to have constant (colors, brightness not changing) render for the rest of the render but the wall, I would suggest using a RaySwitch material for the wall and having a neutral (mid grey, default CoronaPhysicalMtl) material in its GI slot.