UV skewing?

Cadu · Mar 2013

So i was trying to polypaint in zbrush an imported .obj from max.

Even with a very high mesh polycount (30k polys) i was getting a kinda low res painting.

Guessing it could be a lack of uv i set a planar one with some seams painted with UV master. The seams look ok, but the texture itself looks like its skewed. Like THIS.

How do i change the orientation of the uv inside zbrush?

Thx in advance for the help!

BARDLER · Mar 2013

The thing is Zbrush doesn't paint on UVs, so your UVs do not matter until you want to export it out. Polypainting pants directly on the polygons of the mesh, and each polygon is essentially a pixel. After you are done painting you bake the polypaint to your UVs.

cryrid · Mar 2013

Even with a very high mesh polycount (30k polys) i was getting a kinda low res painting.

Even with nicely distributed verts with minimal waste, 30k can be a low number for polypaint (especially if you want nice crisp results).

As for UV Master and the orientation of the UVs, you can try cloning the tool and use UV Master to flatten it. In the flattened state you can use transpose and masking to re position things to some extent, and then unflatten. Then copy and paste the UVs back to the original tool. Minor edits usually survive.

Cadu · Mar 2013

I discovered why the texture looked skewed. Kinda dumb but it's because it is being applied in the UV area with no control. As i selected some standard texture and hit "fill object" it just throw the texture in the planar uv.

After exporting out, setting it correctly in photoshop and importing it back i saw why it was wrong.

Bardler. Thx for the tip, the next stage is try to bake some polypainted textures.

Cryrid. Well before Qremesher the same tool was about 60k poly with bad polypainted results. After setting a UV, ex/importing textures (even with 30k poly) the results were much better.

My main question now is how to maintain the uv/texture with the tool. When i try to merge some tools the texture disappears. Im doing something very wrong here. Is it only baking it?

cryrid · Mar 2013

(60k is still often a low value for polypaint :P)

As for merging, make sure you have the tool:subtool:uv option toggled on before you merge. Afterwards you might have to turn the texture back on on the new resulting mesh

Cadu · Mar 2013

Cryid. I don't doubt that, my results with 60k polys that was very strange, kinda way stretched. After uving things got better. Which poly count do you think is the best for polypainting?

Checking the uv option in the merge section works, but the others tools turn black. Thats because they dont have uvs/texture assigned right?

cryrid · Mar 2013

The required count depends on the size of the area you're painting on, the level of detail you're looking to get, and how efficient the vertices are distributed across the mesh. A million might not even be enough if most of those verts are in the wrong place, or the detail you require is too small. A general rule of thumb might be to think about how many pixels a texture would require to hold the same detail and go from there (give or take a large percent to account for inefficient unwrapping on textures and inefficient vertex distribution on the model). So 60k verts might be comparable to a 256x256 texture (which has 65k pixels). Personally however, if I'm using polypaint for any sort of texture work then I just straight up subdivide the model as far as it can go.

As for merging, you're probably right about the lack of UVs on the other tools; that will probably cause zbrush to do something weirder with them, like collapse them into a single point. You can use Tool: UVMap: MorphUV to get an idea of what's happening to the UVs in your merged result

Cadu · Mar 2013

Good example, couldnt be more clearer than that. Thx alot Cryrid!

UV skewing?

Replies