i am really at a loss here and i hope maybe someone can explain what is going on here.
Please take a look at http://www.cgdigest.com/vray-render-elements/
The post there is already pretty old, but the download link provided there for the .psd file still works.
I tried to replicate the combination of passes in AE, but it only works if i do NOT set my working space to "linearize". I would have expected whenever i am combining passes, i need to do this in linear color space.
The shown example works only when not linearizing, apart from some minor differences in the shadow areas. It works fine in Photoshop obviously as one can see from the .psd file.
I am sorry if this is maybe more of a Photoshop question, but i would really like to know whats going on with these passes. Maybe someone has an idea.
btw: it makes no difference for me when i check or uncheck "blend colors using gamma 1.0" in Photoshop. This .psd file always works. ??
The PSD file provided on that page is not using a linear profile. As you've already discovered, if you want your AE results to match PSD then you need to not linearize your profile.
It looks to me like whoever produced those render elements was not rendering them for a linear workflow. They were not intended to be used in a linear workflow. As a result they, erm, won't work in a linear workflow.
Thanks alot Darby for taking a look. So its like i suspected. Maybe the textures were not linearized and/or some other setting in the 3d app was not correct.
But its good to have a confirmation by someone else!