Uv mapping high detail models for games
polycounter lvl 16
Hi guys, long time no post :P
As It has come to my attention, you can not have overlapping UVs on Zbrush. This is a bit of a problem, since when making game models, you almost always have to overlap UVs to save some space for more detailed textures.
This made me think of which is the best and easiest way to solve this problem. The solution I have encountered would be:
1) UV map with no overlapping on the low poly model
2) Detail away on Zbrush
3) Export model/normal map
4) Import into Maya, and modify the UV to overlap(for example, the models face). Reposition other UV shells to try and get as much UV space coverage.
5) Open up the normal map on Photoshop and modify it to match the new UV.
I think this way work ok, but I think the last 2 steps are a bit tedious and perhaps not the best way to do this. Do you guys have any recommendation on this process?
As It has come to my attention, you can not have overlapping UVs on Zbrush. This is a bit of a problem, since when making game models, you almost always have to overlap UVs to save some space for more detailed textures.
This made me think of which is the best and easiest way to solve this problem. The solution I have encountered would be:
1) UV map with no overlapping on the low poly model
2) Detail away on Zbrush
3) Export model/normal map
4) Import into Maya, and modify the UV to overlap(for example, the models face). Reposition other UV shells to try and get as much UV space coverage.
5) Open up the normal map on Photoshop and modify it to match the new UV.
I think this way work ok, but I think the last 2 steps are a bit tedious and perhaps not the best way to do this. Do you guys have any recommendation on this process?
Replies
A cage is optimized for zbrush, this means all quads, and evenly sized, square quads. Anything else and you'll run into problems when detailing.
A lowpoly will be optimized to use the fewest amount of triangles as possible, and to remove excess geometry that doesn't affect the shape/silhouette of the model.
Generally, there isn't much reason to UV your high, unless you have some really specific need to. Zbrush for instance will auto UV it.
Do not attempt to modify normals after changing uvs or changing your mesh, a normals map is highly dependent on your lowpoly mesh normals and uv orientation.
So the common workflow looks like this:
1. Block out your cage mesh, with even geometry density for sculpting(uv if needed)
2. Sculpt your high
3. Optimize your cage and/or use retopo to create a new lowpoly mesh
4. UV low
5. Bake high to low in app of choice
I'll add these steps on my workflow. A couple of questions: On the 4th step, do you overlap UVs? Wont this be a problem when making the normal map projection? Thanks
DO NOT delete half the model and then bake, mirror and merge, this will mess with the mesh normals and result in a seam.