Vray Geometry Tag 2D Displacement breaks with UV Tiles setting

[zAppledot]

Hi chaos team,

I am running into an issue in vray 6 with the Geometry tag with 2D Displacement when i change the Material Tag Tiles U and Tiles V settings. I don't know how best to describe the issue because it is a bit bazar. So I have rendered a quick video that demonstrates the issue, here is a link to the vimeo video. https://vimeo.com/796772076/31a6ba575c

I have also attached the c4d file so you can test it too, it is a simple scene with a plane and radial gradient in the diffuse slot of the material and the same gradient in the geometry tag. Basically it looks like the displacement affect is cropped to the original UVW tile regardless of the Tiles U or Tiles V setting, and adjusting the U or V makes it so the Vray material and the displacement affect no longer align outside the uvw space. I have tried the Vray UVWChannel shader as a workaround, but this has the same issue.

Let me know if you need more information, hopefully it is not a tricky bug to track down.

[viktor_angelov]

Hello,

This happens as the Gradient is a procedural texture.

If you want to avoid the situation you could either replace the Material Diffuse Texture with a VRayC4DBake texture or you could set a VRayRamp to both Material Diffuse Texture's slot and to VRayGeometry Texture's slot.

[zAppledot]

Hi Viktor,

Thanks for the response. I discovered the bug while while adjusting the scale of a 2d displaced material with simple bitmap textures. But I created the test file without textures so it would be easier to share. But to summarize, the issue happens whether i use a texture or a procedural shader or VRayC4DBake with the procedural shader. I have the same results.

It is as if the texture is scaling independently inside of each uv tile for the 2D displacement, while the material is scaling the whole uv tile. It is more apparent when i use a texture image instead of the gradient on the plane. Here is another video. https://vimeo.com/797402023/c864df64d8

If possible, please have a look at the c4d file attached to my first post and the bug will be easy to spot. Idk if it helps, but it does not happen with normal displacement, only 2D displacement.

Thanks

[deyan.hadzhiev]

Hi zAppledot, I inspected the scene and the problem really seems to be related to wrong displacement for UVs outside the 0..1 range. Usually, the "Multi tile" option in the 2D displacement options helps by considering the tiles outside the original range, but there seem to be additional problems with mismatching displacement and surface normals.
We will be looking into this issue (logged internally as VC4D-1714), but I can not give specific time-frame when it will be resolved. Thanks for reporting this issue and providing the good examples.

[zAppledot]

Awesome! Thanks for looking into it! I just wanted to make sure i wasn't crazy.

[boyan]

Hello, zAppleDot!

Thank you for the report, May I suggest you to check the workflow as attached file.

Cheers,

[zAppledot]

Hi Boyan,

Thanks for taking the time to respond and put together the pdf. The Multi-Tile check box does helped with some of the issues, but there is an artifact when polygons overlap the boundary of the uv space (See attached screenshot where i have highlighted the polygons with artifacts).

You can see the artifacts in this video. https://www.dropbox.com/s/nnc6qucbpq...itile.mp4?dl=0
Here is a dropbox link with the c4d file, I tried to create the simplest scene possible that still produces the issue.

I tested with native bitmap shader vs vray bitmap shader and it did not appear to make a difference.

Thanks again for looking into it. I can work around the issue by changing the uv's of my model and avoid using the scale/tile setting, but if you think of another workaround that works i will be happy to try it.