3 different UV interpolation types across apps, but why?

[Intuition]

So I keep running across this UV problem over the years and it hit me again this week. UV map interpolation at rendertime on subdivided meshes using displacement.

In our 3d world we have 3 ways of interpolating UV maps ona subD mesh at render time. 1. linear UVs. :D [] See some apps/render engines have either smooth UVs or Smooth UVs but not the borders which leaves the borders linear but subDs the rest of the mesh inside the borders. This would help with seam issues on subD meshes that have hard angles at the borders and possibly some pixel distortion. The only problem here is what method in what sculpt app works with what render engine at what settings at rendertime. If you have a smoothed UV mesh but you leave the borders linear then what happens at render time? Well I suppose no seams at the borders and less pixel distortion throughout the rest. My issue with these three methods is that certain render engines do certain things at render time. Modo offers linear on or off. Maya mental ray seems to offer linear UVs by default unless you use the approximation editor. Then you have to specify. Maya Vray has subdivide UV borders check box (a choice between method 3 or method 2) where it is subd the whole mesh or subD mesh with straight borders. DOes Zbrush even do linear borders but smooth the rest? I think the three methods also causes confusion amongst new users depending on which app / render engine they are using. Why do we need anything other then linear uvs? If you use an app like UV layout to smooth out possible pixel distortion then you would never need anything but linear uvs.

Attachments

[MichaelMaehring]

Why do we need anything other then linear uvs? If you use an app like UV layout to smooth out possible pixel distortion then you would never need anything but linear uvs.

because you can´t properly paint linear UV´s in 2D-programs like photoshop

so i would really like to see smooth UV´s in Zbrush - i mean, it´s already there, but until ZBrush 3.5r2 the suv-button would create smooth UV´s, but after switching between the subd levels the UV´s will change to linear

i have mentioned this problem quite often in the forum and to pixologic, and i wonder if it will be resolved with ZBrush 4

[Intuition]

Ah ok, that is a good point. Photoshop post processing. That makes sense because it would be hard to replicate the hard edges.

Still, then the linear borders with smoothed UV center is another interpretation. Guess you can edit in pshop and not worry about seams in certain apps subD uv?

Well, it least I can ascertain what is going on now. This used to trip me up between mudbox, zbrush , maya, max, xsi and mental ray, vray, renderman.