ZBrushCentral

Overlapping UV's max to zbrush

ZBrush Usage Questions
#1

I have a problem when I’m importing a mesh created in 3dsmax8 into zbrush.

I have the UV’s laid out in max with uvunwrap, according to the workflow guide here on zbrushcentral.
I’ve checked if there are overlapping uv’s or inverted ones but there are none whatsoever.
I’ve welded vertices and the mesh is all quads.
UV’s are all in 0 to 1 area.

When I import the file in zbrush and hit uv check I get red streaks indicating overlapping areas.

Anyone has an idea what is the problem here?
Also when I hit UVGroups it is all one color, not the groups from 3dsmax.

Attachments

unwrap.gif

zbrush-uvcheck.jpg

#2

Your 3DSmax export settings are fine. I believe you had two UV points at 0 on the U axis. All the UVs should be within a UV tile (0,0 to 1,1 for example), e.g not on 1, .8 or .34, 0.

I have attached a UV modified version that will work in Zbrush.

I am not sure what options there are for exporting groups from 3DSmax. I think the only option is to place the UVs for each group in seperate UV regions, e.g 0,0 to 1,1 and 1,0 to 2,1 etc.

Other programs allow you to define polygon sets, polygon tags or something similar, which the .obj exporter will turn into groups. Not sure if there is such an option in 3DSmax.

#3

The problem is that when you laid out the UV’s you allowed some of the points to actually touch the line separating UV regions. When the model imported into ZBrush, one of them then actually wound up reading as being on the opposite side of the map. This point then formed one corner of a very large polygon that stretches all the way across the map and overlaps everything along the way.

If you take the texture created by the Uv Check function, flip it vertically and superimpose it over your UV map you will see that the point touching the top of the map region has gotten pulled straight across the map to the bottom of the region.

The bottom line is that when you UV map your models you want to make sure that all the points are entirely within the UV space. Any points that fall right on the edge of the space can be pulled across like this due to the fact that different programs each tend to register the 0,0 point slightly differently.

#4

TVEyes & Aurick:
Thanks! I spent a whole afternoon yesterday figuring out what was wrong there. Apparently the layout function in 3dsmax called Pack UV’s places some UV’s right against the edge so some manual tweaking is required. :slight_smile: