Maya tri-planar projection and GPU problem

[seandunderdale]

Im creating some seat perforations, and I need to have a bump map holes option for medium shots, and a displacement option for closeup. The bump option is where I'm having an issue.

The shader is setup with a suede shader base, going into a bump shader for the holes. Ive had to use the Maya projection method because Im using a tiled circular ramp for the holes, and the Vray triplanar ignore the "stagger" option in the maya 2d placement texture which I need to make the perforations sit in an offset way rather than in a perfectly parallel lines. This all works fairly well, until I try to add a darker shader in the blend shader, over the top of the suede, using the perforations map as a mask. This would have the effect of faking some more depth and darkening the holes. The problem is, the map is totally ignored when used in the blend amount on GPU. Ive attached render of the same shot in CPU and GPU. The image on the left is CPU....Ive flipped the colours so its clear what is happening. The same setup, just switching from CPU to GPU CUDA.

(I wont get into why the CPU render was WAY more tiled, and also had inverted normal maps....thats a consistency conversation for another day)

Im using Maya 2018 and Vray Next 4.30.01

[seandunderdale]

For clarity, the image on the left is CPU, image on the right is GPU. Ive changed nothing apart from switching renderers. My perforation mask works as a bump map, but doesnt work when I try to use it as a mask in a blend shader.

[hermit.crab]

Could you send the scene to support@chaosgroup.com so we can take a look? Mention this thread in the e-mail along with a log from the rendering.

[seandunderdale]

Ill try to package something up asap. In the meantime Ive found another problem with maya projection and GPU...Does the Vray Tri-planar not work with the 2d placement stagger? (if it doesnt I guess thats another bug?) If it did I wouldnt have to use the maya projection node which seems to be full of bugs on GPU.

The CPU perfs (on the left) go straight since projection ignores uvs....but the GPU (on the right) is angled and follows the wonky uvs. The uvs Ive been sent do bend and arent that great, which is why Im trying to use projection to avoid having to re-uv all sort of soft modelled parts.

It seems "stagger" in the 2d texture node works fine on CPU. It doesn't seem to work on GPU.

[hermit.crab]

Sorry to say, it is another issue. The stagger option, indeed, does not work through a VRayTriplanar node. I've logged it (internal bug-tracker id: VGPU-5047) for developer analysis. Do send the scene, so we can take a look at the other report, maybe we could come up with a workaround.

[seandunderdale]

While trying to re-build a scene I could send, Ive actually come across a more simple problem. I cant actually get maya tri-planar to work at all with a simple dotted ramp. Ive attached a scene that works fine in CPU and cant see anything in GPU. Any thoughts?

Maya 2018 Vray Next 4.30.01

[hermit.crab]

I took a look at the attached scene. Using the Triplanar mode of the Projection node with Ramp works fine on GPU. The wrong result in the attached scene is UV related, adding spherical mapping to the object resolves the issue.

[seandunderdale]

Hey Aleksandar. Thanks for taking a look. Ill go back into the scene and try that out, then see if I can get to bottom of the original issue that I posted.

I may be misunderstanding the point of projections, but isnt it so that you dont need to worry about uvs? The way Ive used the all my car interior work is it allows for shading without making lots of uvs consistent in size. Its seems to be ok on CPU, but not GPU in the way it doesnt need the UVs to work.

[hermit.crab]

You are correct. The issue did, indeed, lied elsewhere. It seems whenever the place3dTexture node box is out of the object (when using Ramp) the results are not correct. I've logged the issue (internal bug-tracker id: VGPU-5094) for developer analysis. You may either use the place3dTexture's Fit to BBox button to align the projection to the object or use VRay Triplanar instead.