headus 3D tools

[TwoSheds]

I've been wondering, what exactly does UV Layout do when you select SUBD as the UV type, for a new map as opposed to Polygons?

I know we're supposed to use the SubD selection for UV mapping objects that are going to be put into SubD mode when rendered, but I'm curious as to what's going on under the hood, and how important it is.

Thanks.

[headus]

Have a look at the image below ... the first panel shows a SUBD surface with its control cage in wire-frame over the top. When you export that from your modeling software, its the cage that gets saved into the OBJ file.

The second panel shows what this looks like when loaded into UVLayout as a Poly; you can see its quite jagged. UVs computed from this mesh will be stretched or compressed, in those jagged areas, when the texture is applied to the actual subd surface in your renderer.

The third panel shows what the OBJ looks like when loaded as a SUBD, so its much more like the SUBD limit surface in shape. UVs computed for this mesh are a much closer fit to the shape of the actual subd surface. Also if you load the mesh as a SUBD, you can preview the mapping over the surface itself in the 3D view with the "S" hotkey ... that toggles between the usual poly and the subd surface shading.

If you have the Pro version you can get even more accurate flattening for SUBD surfaces with the Calc Subdivision Targets tool under the Optimize panel. For most organic shapes with relatively even polys across the surface, like the one below, its not required. But for hard surfaces (e.g,. a table) where you might have large polys next to smaller ones (e.g. top of table adjoining the narrow edge), then the additional calculations are needed to get accurate UVs around those areas.

Phil

[TwoSheds]

I see what you mean. It's not something I've had to worry about much though, being that I'm always using either very high poly objects or very low, non-SubD objects.

Thanks Phil!