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Displacement and UDIM Tile issue

ZBrush Usage Questions
#1

I did a search for this but could not find anything close to what I’m experiencing. I have a mesh that has multiple UDIM tiles and I use multi map exporter to bake them out. Initially, I was getting unwanted values in areas I did absolutely no sculpting in which resulted in a general puffing up of the model in render time. I found the solution in storing a morph target before subdividing or bringing back in the original obj to get back the initial shape, then bake the maps. The problem is it worked on only SOME of the pieces. There are a few pieces that refuse to work even though I’m replicating the process exactly on those ones.

I tried an experiment where I brought the UVs of the uncooperative meshes into 0 to 1 space in Maya then back into zbrush to bake maps out and it worked! I only got values in only the areas I did sculpting in. The thing is those UVs NEED to be in the original UDIM tiles and not moved to 0 to 1. If anyone knows what’s going on it would be greatly appreciated. It’s a bit urgent.

#2

I really have no idea as to why this should be happening. UVs should make no difference to how a displacement map is generated and I’ve not heard of anything like this before.

However, you should be able to use the maps you baked out after moving the UVs to 0-1, shouldn’t you? The actual map will be no different whatever UV square it’s in.

#3

Thanks for the reply! I thought of doing that but the problem is the mesh also shares UDIM tile with other pieces that are in that tile. The UDIM tile isn’t JUST the UVs pertaining to that piece, there are other ones sharing it. The only option is to composite and paint out in Photoshop but I don’t have that time. Either that or go to the otherside and use Mudbox. Again, thank you :slight_smile:

#4

Are you absolutely sure you are using the ‘Morph Target’ option in Multi Map Exporter correctly? Frankly, the most likely explanation for the error is that the displacement is being generated for the wrong version of the base mesh. I can’t think of any reason why the UVs should affect it (and MME is used constantly by others without probems).

If you got this working in MME you could use the ‘Merge Maps’ feature to merge the maps that occupy the same UV tile.

#5

Yes, I’m applying the exact same process to all the parts (it’s multiple pieces) and it works perfectly on those but for some reason these few won’t comply. I do have merge maps turned on and I’m storing the morph target the same way on all the subtools. I’m so confused

#6

Did you store the morph target first and then import the original model?

#7

Thank you for your time and help! I hadn’t thought to do both store a morph target as well as reimport the mesh. I just tried it but still got the same result :frowning: It’s like zbrush refuses to use the initial morph and original untouched mesh but defaults to the shrunk basemesh after it’s been subdivided.

#8

That’s what the MME ‘Switch MT’ option is all about. It makes sure that the displacement maps are generated from the imported mesh. When the plugin needs to go to a higher level (for example, if texture maps are being created) the morph target is switched, back to the modified mesh.

The workflow would be:

  1. Go to lowest subdivision level.
  2. Store morph target.
  3. Import original base mesh.
  4. Make sure MME>Export Options>Store MT is on and other options set.
  5. Run MME.

If you can let me see the ZBrush project file I will try and find what’s wrong. Save out and include the MME settings as well, through the button at the bottom of the Export Options. (Upload the file to Dropbox or somewhere.)

#9

Hi, Tried that exact process but still getting the same issue :frowning: Unfortunately I cannot share a studio asset otherwise I’d love to have you take a look at it! Thank you for your help :slight_smile: