Camera Projection issues - Vray 5 | Maya 2020 -

[mattconwayart]

Hi all,

I'm wondering if you could help me out. I'm running a couple of camera projections (cave paintings inside of a cave), that are vray blend materials, because I want the paintings to go over the base rock layer. I'm projecting those paintings from camera, so I have control over where they are placed on the walls. My material is pretty basic: the base rock material, and one coat layer of the painting material with the camera projection being used as the blend, or alpha.

I'm getting something weird happening, and I'm not sure whether its because I'm using a camera projection inside of the blend material, or if it's just some setting that I'm missing. But it appears as though the camera projection map is somehow being projected behind the camera, or rather, the alpha I'm creating is being ignored behind camera. I've never seen anything like it before. I am uploading photos so you can see what I mean. I've simplified the material to just be a grey vraymtl as a base, and a green vraymtl as the coat, with the camera projection being the blend amount (alpha).

Am I just missing a setting somewhere here?

Uploading a the test file as well.

Thank you in advance.

[mattconwayart]

Adding the file as promised -

[Morbid Angel]

Hi, you need to post direct link to the files I think the link you posted is incorrect.

[mattconwayart]

Sorry about that, Dmitry -

Adding a direct link:

[Morbid Angel]

Alright here is the scene. There are a couple of things you need to do, I've annotated them in the screenshots.

[mattconwayart]

Thank you so much, Dmitry!

[seandunderdale]

Are these workflows somewhere in documentation?....because I wouldnt know to go and change default colours like that.

[mattconwayart]

seandunderdale, unfortunately, not. I searched the docs for answers. But in fairness to Chaos Group, this is par for the course in regards to camera projections. Camera projections in Maya are, as with almost everything else in the program, clunky and out-dated. I normally project everything in Nuke and then composite the shot, but in this case, because of the nature of the materials, I wanted to do it in-camera in Maya. Big mistake!

By the way, Vray 5 completely ignores camera scale. It is shown in the viewport correctly, not not rendered with the scale! I had to do the old-school math calculations to change my lens to accommodate my 1.3 (130%) overscan, and some more old-school calculations for my render output image size. Projections in Maya are dying - not a slow - but fast death.

Thanks again to Dmitry for poking around my file and getting me the answers I needed!

[Morbid Angel]

seandunderdale, the color settings are a maya logic, its not related to vray. So for example, maya needs to know what color is the texture if the texture does not exist, or if the texture is not tiled. In this case, we want the projection to only be visible by camera eye, but by default it will be tiled outside the projection eye. In this case we must uncheck wrap u and v, so the image is no longer being tiled, then maya will return default file color which is grey. That's why you must set it to black because you want to use the projection as a mask so it must be pure value either black or white.