Why is it that even though you’ve already uv mapped a model and removed all the overlapping, that Zbrush still pushes out a distorted normal or displacement map? I mean, shouldn’t allign exactly where the UV map is? Or am I doing something wrong thats causing these distortions?
I understand why a color map would istort if you paint in photoshop, but since its in zbrush…it should be matched exactly wouldnt it?
I used HeadusUV layout to lay out my map.
from my understanding the reason is this:
when you subdivide your mesh, it actually stretches your UV’s out a bit, causing the seams to show up when you use your original pre-sculpted mesh. If you’re going to use your original mesh as your rendered object (and not the one you’ve actually sculpted on), you need to store a morph target for the original mesh before you actually sculpt it.
I stored a morph target, but the problem with that is, I reposed the model. The gestures are way off, so would that still be usuable?
And what should I do to prevent distortions if I don’t have the morph target?
What are the steps that you’ve followed, then? Where is the posing coming into play? Can you show examples?
If you didn’t store a morph target and don’t want to reimport your original model into level 1 to restore the base mesh then you need to generate a cage mesh. You do this by going to level 1 or 2 and turning on Tool>Geometry>Cage. ZBrush will calculate a cage based upon the highest subdivision level. You can then create your displacement map. You will also need to export the new cage geometry and use that with the map.
Cages or restoring the base mesh are not necessary with normal maps, however.
Ok sure, I’ll show an example
I’ll describe the steps first.
1.Built a base cage in Maya, then exported as an OBJ.
2.UVmapped the OBJ in HeadusUV layout
3.Brought OBJ back into Maya to tweak UVs.
4.Exported OBJ out of Maya, then imported OBJ into Zbrush 3.1
5.UV checked, then created a morph target. (repeat step 1-5 for every accessories seen on the turtle)
6.Modeled in zbrush.
7.Posed
8.Modeled some more, then added details like alpha brushes etc.
9.Go back to level 1 mesh. This is not the object I imported. Because of the posing, and added geometry, the base mesh changed significantly. I basically ignored the original base mesh I saved in my morph target.
10.Exported level 1 and 2 OBJ from Zbrush.
11.Exported normal map with the zmapper. Exported displacement map with the displacement map plug in. (looks fine in zmapper, but the map itself when viewed, looked distorted on the sides.)
12.Imported all these into Maya and rendered in Mental Ray. Don’t look exactly like Zbrush. 
What I’ve tried.
I tried zmapping normal maps onl level 1, 2 and 3. I dind’t know you can do it on anything except for 1. I’ll post the image of both maps here.
Displacement maps were exported at level 1.
Maya Mental Ray vs Zbrush
Displacement map. It looks really smoothe, but it doesn’t look like it fits the UV map. The UVmap itself is pretty jagged, this one looks like it goes outside of it. IS that normal?
Level 2 Normal map. Looks significantly different from level 1 normal map.
Level 1 normal map
On both, the sides are pretty distorted, and I get a cavity on the top end. One of them I forgot flip, but I’ve reflipped it since.
Morph Target Turned off here. It is the cage I’m applying my normal maps and displacement maps on. I also use this mesh to export to Maya.
This one is with the morph target turned on. I don’t use it because it looks dramatically different than what I have now. I’m not sure if this affects the UV’s or not.
What I tried to do to fix the problem:
Took the new level 1 mesh, exported it, and UV mapped it. Took that same OBJ, imported it back in to replace my other level 1. What happens here is…the whole model blows up. I’m assuming because of the readjusted UVs. I used Headus to fix it.
Another thing I’m noting. When exported the obj, all my UV’s were separated. I had to reattach it with the sew UVs. Hope that gives you a really good idea of what I did. Thanks in advance.
As for that thing you suggested.
Tool>Geometry>Cage
I’m not too sure exactly what it does, but since I’m no longer using the original base one maya mesh, I need to use it correct?
When I did it, the geometry at level 1 turned all funky. I then went to level 2 and then back to level 1, it looked normal again.
I’ll play around with it somemore.
PS: What is the difference between Sample and Subdivide in zmapper?
Ok ok I’m really frustrated now. I’ve been trying for over 2 weeks now and I still can’t get rid of distortions.
Answer me this.
Does it matter how well your UV maps are laid out for the model? Wouldn’t Zbrush interpolate everything accordingly to the UVs?
I mean, I flattened it out well I thought and removed all overlaps. But every time I export a normal or displacement map, I get really distorted mappings. It looks really awkward in Maya.
When I use AUV mapping in Zbrush, then export it out to Maya, the distortions are gone, but…I don’t want these cube/matrix layouts.