Blackplate "bleed through" when matte material used


Repost of an old issue wondering if there’s been any progress…when trying to use a matte floor to composite a vehicle onto a backdrop, in certain reflective areas of the vehicle the backplate becomes visible…indeed it may go through the whole thing. I had thought I could spot-fix this in photoshop by doing another render with a plain white backdrop to overlay on the trouble spots and it didn’t work, it didn’t match up at all even though the floor plane was set to invisible in reflections.

EDIT…it not the case that the bleed through is only where the matte plane is behind the subject, it just has to be there.

(Andrew le Bihan) #2

A model would be great. As simple as possible.



Just to make sure: what would be the expected result for those reflective areas?

Is the new backdrop bleeding through as in “solid objects become transparent where the backplate reflects”?
Or is the matte backplate bleeding through as in “you can still see the old backplate but want to replace it with the new backdrop”?


Objects become transparent in areas of high reflectivity, I sent Andy a file. I wonder if it is actually some sort of unrequested “reflection” effect using the backplane texture.


Sounds like rays from the backplate are considered transparent even if they should not.

Anyway, you should be able to easily fix this by painting on the alpha channel in photoshop since the areas surrounding the reflective areas are probably all solid.


The fix is it looks right in a Brazil render. There are a few things about background images not working yet.


Okay, but that fix would be no fix for me and probably a few others, since i don’t have Brazil :wink:


Are you seeing the issue? 'cause the alpha channel editing in Photoshop thing sounds totally unrelated to what I’m seeing. Anyway, if you like Neon you really should get Brazil, both to see what it can do and to save your butt when it falls down.


I did try neon some time ago for it’s viewport integrated workflow. But Neon is pretty basic. Since I have both V-Ray and Maxwell, I don’t think Brazil is an option I would go for :wink:

Your first post referred to fixing things in photoshop and compositing a backplate. Your workflow sounded rather convoluted and I still think I didn’t really get what exactly your workflow is. So I just wanted to find out if I could help in more general terms.

Anyway, if your problem is fixed with Brazil and Andy can look into a possible bug with Neon, I’m fine with that-