matte bug (or me just having a brainfart)

[super gnu]

ok so i didnt use the matte object setting in the object properties for a loong while.. but either im forgetting something i used to know, or its broken.

simple scene, interior, boxy, 1 mesh, all faces pointing in (walls dont have thickness) has a window with vray sun and sky. physical camera inside.

i have another box inside the room.

renders absolutely fine.

i select the room, set matte object, turn alpha to -1 cut vray sky from env slot and put in the ref / lighting override slots and hit render with same irradiance and lightcache settings.

in theory the box should render with the same lighting as if the room was still there, but cut nicely on a black bg.

what i actually get is the box really brightly lit as if the room isnt casting shadows any more.


what did i forget?

[super gnu]

matte problem.zip


anyone? im still stumped as to what im missing, and its quite a major bug if it is one..? it only happens when i have gi enabled (tried imap, lc bf ) you can see when it does the gi calculations, the direct light is passing through the matte object and affecting the gi calc. direct light is still occluded in the final render, but the gi is obviously off the chart, as it was calculated in direct sunlight. also ive noticed if i tick affect shadows on the matte, i get shadows from the non matte object on the matte as if there was direct sunlight hitting it.

really dont remember this issue before.. ive attached an embarrassingly simple scene that exhibits this problem.

max 2011 vray 2

[super gnu]

please.. could somebody at least confirm if there is a problem or not.. i have no idea if im making a mistake or its broken.. somebody out there must be using matte properties..? im up against a deadline and have no alternative solution.

[super gnu]

amazing.. 61 views and no one can confirm or deny if the whole matte system is borked with gi?

at this point id even be happy if someone just told me i made a schoolboy error and to stop posting silly questions.. beginning to feel invisible .

[Codi]

We have the same problem, have you tried disabling "no GI on other mates" in mate properties? We also avoid this problem using "invisible to camera" instead of mates whenever possible.

[super gnu]

ok so if i untick "no gi on other mattes" it fixes the lighting problem, but then the matte appears to show up opaque in the alpha, even if i have alpha set to -1..?

confusing the hell out of me, ive used the matte settings on 100's of projects and i dont remeber this issue.

[DANIEL_BACHMANN]

I've got the same problem here and have not found any solution, it is very confusing and produces no logical product.

[pixela]

I think this is because matte has a problem with shadows and doesn't work as it is ought to be.
I have another scene with a matte object, which I can't get proper shadows or good shadow quality as well. I reported this but can't get reply.

[DANIEL_BACHMANN]

Thank you for reporting it, let us know what the outcome is. I am thinking of proting my actual project to mental ray again because there it works like a charm.