Clean transfer of UVs after remesh?

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I have to remesh an object to do some mild boolean-ing and less mild fracturing. Is there a suggested way for a clean UV transfer from the original to the remeshed object? I realize the vertices aren't 100% in the same place, but it seems like they're closer than the new UVs would indicate.

In case it was an issue of point/vertex density, I tried this with inappropriately dense meshes, as well as doing a transfer by way of a very dense scatter, and the result is the same.

The weirdness, predictably, happens along the edges of the UV islands, so I assume the culprit and salvation lies within some sort of vertex split workflow.

Surprisingly, the boolean and fracture hold the UVs pretty nicely (post the remesh UV mangling).

Three pics attached--the original, after the remesh, and then after the boolean/fracture.

Thanks for any pointers!

Attachments:
orig.jpg (350.2 KB)
remesh.jpg (403.4 KB)
fracture.jpg (408.1 KB)

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You could use the Labs UV Transfer node. I use this to transfer UVs after certain operations. If the original model has a uv2 channel, you would have to assign a uv2 channel in the Labs UV Transfer. Are you also creating UVs on the inside?

Glen
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Hi,

one possible way maybe:

  • creating classes from uv islands (on the base mesh)
  • classify each polygon on the remeshed mesh by the class of the uv island, which closest distance to the center point
  • now you can calculate the distance to closest island foreach vertex (using its prim class)
  • at the end primuv() can transfer the corresponding uv from base mesh to the target mesh

Attachments:
uv_transfer_avoid_seams.hipnc (333.1 KB)

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Are you on Houdini 19?
They updated the Remesh Sop with a parameter to preserve the UVs.

Or if you are still on Houdini 18.5 you can check my Fast Remesh SOP [www.sidefx.com], which has an option to preserve UVs as well.

Or if you want to do it manually, just assign the UVs island edges to the Hard Edges group of the Remesh Sop.
Edited by Andr - Jan. 18, 2022 10:37:57
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Thanks for all your help! The UVs came from the Zbrush model.

The labs UV transfer tool worked really well, but the "harden UV edges" option in the remesh did the trick perfectly. Hadn't even noticed that before!

Aizatulin, I'll give your method a go during some downtime--there are a few tricks in there I'd like to have in my brain.
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bentway23
The labs UV transfer tool worked really well, but the "harden UV edges" option in the remesh did the trick perfectly. Hadn't even noticed that before!

It's recent indeed
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