I’m using Decimation Master on some hi-poly models and trying to UV some meshes that have already been decimated. Only AUV will even work (PUV and GUV just hang because the mesh is 900K -1.1M poly). ZBrush will apply the AUV tiles no problem, but they are unusable - artifacts along all the corners/seams between the faces.
Is this a known limitation of Decimation Master? Do you have to UV prior to decimation?
Thanks in advance
b
UV Mapping should always be assigned at the lowest subdivion level. If you have a high resolution model that does not have multiple levels you should decimate it prior to assigning UV’s.
AUVTiles places each polygon on a separate square of the UV map, with a border surrounding it. If you do the math, you’ll quickly see that it’s just not possible to create good mapping when a model has hundreds of thousands of polygons. Even at the largest possible texture size, your map would still end up being mostly borders with very little actual texture space. 
Thanks Aurick - that does makes sense. However, it leaves me with the problem of having to UV and then decimate, and when I do that I have problems with the UV’s not really matching up on the decimated mesh - it gets distorted - see the attached pics.
Is there a way around that issue?
That’s something that’s going to be inevitable. When a model is decimated its topology is by definition going to change. That will in turn force the UV’s to change in places. Decimation Master keeps the UV’s as close as it can to what you started with, but there is no way to prevent some distortion. The heavier the decimation, the more you can naturally expect to see this.
If having clean, distortion-free UV’s is critical to you the best option is to decimate the model and then UV it. There’s no reason you can’t then import the new UV’s into the model so that you can do things like project polypaint.
Thanks Aurick.
I guess that puts me back to square one though - except now I know that AUV isn’t going to cut it for UVing the decimated mesh. The other options in Zbrush won’t seem to run on such a heavy mesh (1.2M points, after decimation). I had gone to AUV tiles anyway because I understood those to be the “optimum” quality (as long as you didn’t need to 2D paint).
Perhaps the short answer iis that Decimation Master just isn’t a good way to go if you need detailed texture maps on your post-decimation mesh, unless your mesh is low enough poly that it is still feasible to unwrap it.
Too bad - I thought this was going to work great
b
Just tried an experiment and reduced the polycount down to 300K via decimation master, and then used PUV tiling. This also generated crazy artifacts in the texture map I painted via PolyPaint.
If AUV and PUV won’t work, what method can I use to UV a decimated mesh?
Thanks
b
Here is the result: one image is the decimated mesh, with PUV applied after DM, and some rough Polypainting. The other is the resulting texture from “new from Polypaint”. This is the artifact problem I had with AUV as well. This only seems to happen to meshes that have been run through DM. Is it something I’m doing wrong?
b
