sculpty LOD and textures

I made an icosahedron with it's 12 vertices each being 4x4 sculpty vertices so that it stays in shape at 9x9 LOD level (done with numbers, not a 3d program; all the rest of the sculpty vertices are in the middle). Texture repeat set to 32x32 fits once per face as expected at the highest LOD, but when moving away, it doubles the repeats per face at each LOD step. I presume that's because it's fitting the same number of repeats to the UV map with less vertices. Does anyone have a means of preventing this? There'e not much point in having the shape LOD-proof if the texture is going to jump instead!

Moving multiple vertice to the same point will have this effect. When people talk about doubling up on vertice to get sharp edges they are usually talking about on a nurbs cage. The actual mesh generated from the nurb surface will still have interpolation on the higher levels.

If you import your shape into Blender with my scripts, then go to multires level 1 and Apply Multires, you'll get a pure 8 x 8 faces. You can then turn multires back on and add 2 levels of simple multires. If you bake the mesh then, you'll get a LOD resistant shape that doesn't have texture jumps as the 16 x 16 and 32 x 32 faces levels will be correctly interpolated from the 8 x 8 mesh.

Thanks. I will attempt this in the hope that by doing so I will learn enough to understand it!

I tried this advice on our cube example (from the LOD tutorial: http://blog.machinimatrix.org/2008/06/04/precision_sculpties_lod/ ). I did some experiments and i found, that using "simple subdiv" instead of "catmull-clark" does the trick, when adding the multires levels. Is it that, what you meant with "simple multires" ?

Yes. When you add a multires level, you can set it's type to "Simple Subdiv" or "Catmull-clark". Simple just subdivides the faces leaving the shape intact, whereas Catmull-clark also does smoothing so you get a rounded shape.

Well, I guess I am still too lazy to learn Blender, so Idid the interpolation by calculation and it works pretty well, (once I remembered to do it per triangle, not per quad). There is a bit of jittering which I attribute to the rounding to 8-bit precision (Ugh!). Easy to avoid using multiples of 4 with rectilinear shapes but not with the icosahedron. I'll have to apply this to all my other sculpties now. Then maybe I'll set aside a week to learn Blender. Is there a script to read in a list of vertices from a text file? I could use that.