Multimattes and Environment Fog ?

[bernhard]

I just realized that my RGB Multimattes are influenced by the Environment Fog.

It became an issue when loading 32bit floating .exr into my composition.
If I want to use them as a mask, meaning.. shuffling them into the Alpha Channel... the mask doesn't do it's work, because I don't have a solid mask anymore.

Instead of having pure white and black values, I am getting grey values in between.
So I have to Color Correct them first, and then shuffle the RGB Channels into my Alpha Channel.

Hmm.. curious if this is wanted ?
I mean... that the Multimattes are effected by the VrayEnvironment Fog ????

And curious.. if there is a chance, to render the Multimattes additional in a separate Pass without the Environment Fog... meaning.. in one shot.. without setting up any additional render scene.

What you think about that ?
How to handle that ?

[svetlozar.draganov]

I'm going to propose an interesting solution which is possible thanks to a bug with our software which in this case acts like feature
The bug is that the Environment Fog is currently not written in deep images, so if you set V-Ray to export a deep .exrs and at the same time regular .exrs you will get two outputs one with fog and another one without it, then you only need to get the multimatte element from the deep .exr and that's it.

In order to export deep .exr and regular .exr at the same time activate V-Ray Raw Image File export and Separate Render Channels export:


Please note that with that setup you will get the following error message at render end but don't worry everything will be written correctly.


The above error will appear after each render which might be a problem if you intend to render animation but if it that's the case just run the rendering trough BackBurner and it will render all the frames just fine.

[Neilg]

The bug is that the Environment Fog is currently not written in deep images, so if you set V-Ray to export a deep .exrs and at the same time regular .exrs you will get two outputs one with fog and another one without it, then you only need to get the multimatte element from the deep .exr and that's it.

This is actually a great feature!
When you fix it could you add this as an option? or maybe turn it into a render element when writing normal exr's?

[Seraph135]

How soon might we see a fix for this issue? I don't have the luxury of rendering out deep exr's on my current project and would really like to have multimattes not affected by fog.

Tim J

[svetlozar.draganov]

Its marked as a low priority issue so I believe it won't be fixed very soon.
Another option would be to turn off filtering of the Render Element - by doing so MultiMatte element won't be affected by the Fog but it's edges will be jagged because of lack of AA.

[miguelortega]

..this is a huge problem...low priority?

[svetlozar.draganov]

I could raise the priority if you would like.
Have you checked the proposed workaround bellow?