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Problem with Zbrush AUV Tiles
Hi everyone.
I have a question about xnormal and Zbrush, hope to find help here, because it drives me mad.
I export a low poly mesh and a high poly from Zbrush with the AUV Tiles. Then I wanted to bake a normal and ao map with xnormal.
When I apply the maps to my low poly model in maya, It lloks alway crappy, because of the seams. Every face has ugly seams around it.
So my question: is it possible to use the AUV Tiles from Zbrush with Xnormal ? Does anybody knows the trick ? Or do I waste my time with this ?
Perhaps anybody has got a link to a tutorial I missed.
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Unfortunately, AUV tiles are primarily designed for use with polypaint and projection master on High Poly models, and are really not very suitable for actual LP "ingame" assets as they would be almost impossible to paint over in Photoshop.
The general idea is that you apply the AUV tiles to the HP mesh and then once the polypaint is done you then Bake the textures etc. over to a LP mesh with a good set of UV's.
You could try flipping the Green Channel in the normal map and see if that helps (though afaik Maya and xNormal use the same axis for normal maps), though for a cleaner solution i would recommend that you create some "Game ready UV's" and bake the maps onto them.
Could you post some pictures (and the models if you want) so we can take a look at the problem.?
If you want to post the models, i would recommend zipping it and then uploading it to DropBox (using the free account) and then posting the link here.
Hope that helps!
Thank you for your replies, guys. I increased the resolution of the textures and it looks better. Perhaps this was the whole problem.
I know, the AUV tiles are crap, but I need the models only for illustrations from one angle. I have to build and render a lot of dinosaurs for a book project and I got no time for laying out the UVs.
The good thing is, that when I have my normal and ao map, I don´t really need another texture, because I will do little details in the post in Photoshop.
Glad you manged to sort it 
If you are just painting them in photoshop can you not just use Zapp link?
I think, for normal and vector displacement maps, you need to plan very well where you place the UV seams.
In the case of simple base textures the UV seams are not so noticeable... but, in case of normal maps, you'll notice a lot where they're located. There are three factors that multiplies the seams's effect:
1. The pixels don't match. As smaller is the texture the more you'll notice there's a "color-crack" there.
2. The diffuse lighting will do strange things due to the tangent basis duplication. The lighting won't be continuous.
3. The specular lighting is usually computed using (N*H)^n, so each minimal error will be exponentially increased.
If your model has lots of UV seams then gonna look very bad.
So, my first suggestion is this one: try to hide the UV seams with hair, cloth, etc.... or put the UV seams in the bottom of the feet, etc... Forget automatic methods like AUVs... they simply won't work. Try to minimize the UV seams and place them strategically !
The second suggestion is other: there's an option in the ZBrush OBJ exporter called "Merge UVs". Well... enable it. That will weld the very-close UVs, removing potential UV seams due to the floating point's intrinsic error.
I hope it helps.
Thank you for your replies. The normal map and ao maps are really looking good at the moment.
But there is something strange with the ao map between the legs.
It looks like a reflected image of the opposite leg. I don´t know how to describe it better. You can see it on the attached images. Very strange...
Seems the rays traveling too much in those areas.
Use cages to limit the ray distance. Be sure they cover completely the highpoly model and check in the "Use cage" option in the corresponding lowpoly slot.
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It's probably becuase you have your settings so that when it exports a mesh, every egde is seperated, so every polygonal face is it's own island, you can chancge this under Tool>Export then clock the little MRG button.
But isn't using AUV incredibly bad to texture? because you won't recognise any part of the model?
(thinking about it, that group thing prob won't work, but give it a go:P )
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