Multiple Textures on one model? - Polygroups?

system · April 16, 2009, 9:06am

I’m sorry if this question has already been asked- but the search function turned up nothing relevant for me.

I am currently working on a model for an independent study under my Game’s professor, to use Zbrush to build a complex model for use in a game engine.

I’m planning to follow the convention of using two texture maps for the whole model- one for the head, and one for the body. Now, I have my base-mesh completely finished, and I am preparing to UV map and bring the obj. into Zbrush: but I know that Zbrush will crash when generating a normal map if UV coordinates overlap.

What is the convention for dealing with overlapping UVmaps? (for example, having both hands overlaid together, or having the head use separate files for normal map/color info than the body.

I have a hunch it has something to do with polygroups- but I can’t find anything here or in Zbrush’s documentation.

Any advice on the proper conventions for building models for games with multiple texture files would be greatly appreciated! Thanks!

aurick · April 16, 2009, 10:21pm

Use Tool>Polygroups>UV Groups to regroup the model based on the UV regions. Then Tool>SubTool>GrpSplit to break the model into SubTools based on the groups. Now you can use ZMapper on each SubTool individually to create your maps.

system · April 23, 2009, 3:21pm

Thanks for the heads up!

It took me a little bit to understand that by ‘UV regions’ it’s referring to the separate quadrants of the UV map. The Grouping by UVs command didn’t work for me UNLESS I only had one map in the 0 to 1 space in Maya.
When I put the other in the 0 to -1 space, the polygroup feature worked as you described-- but my question is how to make this carry over back into Maya.

This may be my lack of understanding in Maya speaking- but from what I understand, all textures must take place in the 0 to 1 quadrant, particularly when exporting for a game. (I know the Panda3D engine works by assigning a separate phong material to each set of faces that uses a different texture map.

If I do build the model with the second texture map in the 0 to -1 space, how would I then shift the texture and the UVs back to the 0 to 1 space for exporting from Maya for use in a game engine?

http://www.rpi.edu/~jalbep/Misc/Question01.jpg
If I have to set the model up like this to make the UV groups work in Zbrush- how do I perfectly shift the 0-(-1) UV map back over so that it will still perfectly allign with the textures I output in Zbrush?

–

The other thing I am concerned about is overlapping UVs in the same space.

For example- I am trying to be economical with my texture space, so the UVs for the hands/feet overlap perfectly. They are part of the same UV region, but -do- overlap. Even if I divide the mesh based on UV regions, those overlapping meshes will still be there, gumming up the works.