Vray UVW placement vs. Rhino Texture Mapping

[Ibear888]

Are Vray UVW placement and Rhino Texture mapping redundant? If setting UVW placement in Vray, is it required to map the texture in Rhino? Does Vray UVW placement supercede any Rhino texture mapping or does it purely build upon it?

If this is covered somewhere, I'd be grateful for a point in the right direction.

thanks,
Jeff

[Peter.Chaushev]

Hello, Jeff,
The V-Ray UVW Placement asset builds upon the UVs set in Rhino as you guessed.
Simply put, the V-Ray texture placement parameters manipulate how and what part of the texture fits within the projection frame that the native Rhino texture mapping applies on object surfaces by positioning / rotating / shaping / repeating that projection.
All this is true only when the Type parameter of the UVW Placement asset is set to "2D (UV Channel)". The other types completely override the native Rhino object UVs and project the textures independently (e.g. 3D world or Environment Screen types).

Main advantage of using UVW Placement assets in combination with native Rhino texture mapping lays in their randomization options (stochastic tiling included). The following webinar segments explain this in a bit more detail: https://youtu.be/eKxYIzFiybg?t=1713
Hope this helps!