ZBrushCentral

Changing UV Mapping later on

ZBrush Usage Questions
#1

Hi, got a couple of questions for all you experts

I have a model that is in late stages of development, but I want to now change the way the UV mapping is done. Problem huh? More specifically, its currently GUV mapping and I want it to be non-overlapping spherical map, so I can play around in photoshop, and generally control the resolution of certain displaced areas. So here goes…

Firstly, how can i rearrange the texture into the new UV layout? I have done some preliminary tests, and the best way seems to be transferring the texture info to the object by tex-> col, remapping it, and then picking it up again with col->tex. This seems pretty good, but does anyone have a better way.

Secondly, how can I make a spherical UV with no overlapping? I read somewhere that you can store a morph target, smooth out the model and apply your mapping, then restore the target. This makes sense to me, but when i tried it, the UVs got completely scrambled. It was like the the beginning of the UV map was stretched right across the map, covering over all the rest of the texture detail. I’ll try to supply a picture of this…

Is there any way for me to export my base-level mesh, modify the UVs and reimport into ZB and retain all te high-level detail?

crossing fingers this all makes sense

heres a WIP of the model rendered in max:
http://karter.fdns.net/dan/pics/zbrush/eccles19.jpg

#2

Another way to transfer textures from one model/mapping to another would be the Ken Brilliant Method. A combination of that approach and the one you describe in your post should work.

As for changing the UV’s, you can indeed export level 1, remap it, and then import it back into level 1. The new UV mapping will be carried across, and provided that your point order has not been changed at all you will not lose your work at higher subdivision levels. What will be lost is any texturing that has been done for the model, since that is dependent upon the UV’s rather than the geometry.

#3

OK - thanks for the reply.

Reimporting the base mesh sounds like a really cool thing to try. Dunno how you guys do it… Question is - could I store the colour information on the mesh still? Because that would mean I would be able to create a texture from the new UV coordinates!

#4

Yes. Vertex shading is independent of the texture, which means that changing the model’s UV’s will not change the vertex shading. Just make sure to apply the vertex shading at the highest subdivision level. The catch is that unless your model has sufficient polygons to allow one polygon for each texture pixel, you will lose quality when converting the texture to vertex shading. That quality will not return when the vertex shading is then transferred to the new texture.

#5

aurick, got another question for you. I tried exporting the level 1 obj into 3DSMax, changed the UV map and re-exported. ZBrush was not happy, and said it had a different number of points.

In fact, I tried importing, then exporting straight away and it stil didnt like it. This is using the default import/export habware plugin. Do you know what would cause this and/or where I can find out about how to fix it?

#6

I don’t know Max well enough to know what settings are involved. But something in your import or export settings is apparently causing points to be welded. This changes the number of points, which in turn affects the ability to import the mesh into ZBrush again.

#7

Could it also be somethign to do with the number of digits used in the storage? I know this was causing people grief in max for lots of other unrelated reasons?