Subdivision/Mesh Buckling After Maya Mesh Transfer Attributes Projection

Deqa

I'm getting buckling/unwelding around the collar on my retopo'd mesh upon projecting it onto my original mesh using Maya's Transfer Attributes, and I don't know why.

I retopo'd my flat panels from Marvelous, transferred the UV's from the original flat panels out of Marvelous (using Maya's 'Transfer Attributes' feature), projected those flat panels onto the 3D mesh from Marvelous, which created my low poly, and then started welding / subdividing my low poly 3 times > project onto my 3D mesh from Marvelous for a final 'high poly pass'. It just created a lot of buckling. I'm not sure if I destroyed the UV's by repairing some edge loops on torso area of my low poly during the welding process or if I just have bad topology around the collar in general, which led to too many polygons around those wide polygons and thereby an unwelded, buckled collar mesh-looking-thing. I did, however, try to ensure that the UV's were in the same space between my decimated version and my retopo'd version, that I am sure of, and I tried not to mess up the UV borders / seams on my retopo and my decimated version but there could have been slight misalignment between the two on the U + V axis.

THE MARVELOUS DECIMATED MESH + ITS UVS


MY RETOPO + ITS UVS



MY RETOPO SUBDIVIDED 3 TIMES + ITS UVS + THE BUCKLING / UNWELDING IN QUESTION

Deqa

The problem could be that the UV's on my retopo'd flat version don't match the UV's on the original decimated Marvelous mesh? As you can see in the bottom image, around the collar, the retopo'd UV's around the collar poking out of the original decimated mesh's collar UV's.

poopipe

Try projecting in a different space

Kanni3d

I feel like you've done all the steps correctly, but you may have an extra vertice/assyemtrical low-res when you're projecting, thus causing that bad result with the welds. Gotta keep in mind that whatever is being projected/welded, needs to have the exact same amount of edges/vertices (can't weld a cylinder with 18 edges to another element that has 23 edges etc...)

Deqa

Kanni3d said:

I feel like you've done all the steps correctly, but you may have an extra vertice/assyemtrical low-res when you're projecting, thus causing that bad result with the welds. Gotta keep in mind that whatever is being projected/welded, needs to have the exact same amount of edges/vertices (can't weld a cylinder with 18 edges to another element that has 23 edges etc...)

Yeah, I'm moreso referring to the projection of my low res (which has been subdivided 3 times) onto my high res. So I've already completed the first projection from my flat UV retopo > decimation to create the low poly. Now I wanna take that low poly, subdivide it, and project it onto the high poly once more. But like, yeah, I'll try that. I know that maybe my vertices on the collar were pushed slightly forward in World space before I even projected low onto high, maybe that could be it. I also had some success with actually trying to make the UV's on my low poly and the UV's on the decimation match 1-1 around the collar and it reduced the tearing by 30%... so I am kinda confused.

Deqa

I found out the problem was that the collar topology; when subdivided and projected, produces uneven polygons between the collar and the torso it welds to. My question now is, how do I fix my low poly's topology so that the collar welds to the torso when subdivided? Could it be that there's a pole (in red) so near to the collar? :S

Kanni3d

@Deqa
Here's your problem. You got mismatching amts of edges from the collar element to the shirt.  The poles will also not give the best results of course, so add more edges if needed. Keep your elements symmetrical and evenly spaced edges/polygons too, before you morph them/project.

Either fix the mismatching amt of edges in the projected phase, or in the flat unprojected phase. Weld everything to make sure, then sub-d and project. 

Deqa

@Kanni3d
Hi Kanni, I fixed the mismatching edges and it still produced the same warped result around the collar when smoothed. Could it also be that, upon welding all my low poly pieces together, the UV borders are now messed up? And the whole process requires my UV's to be 'separated' in a sense. But welding my low poly pieces together welds the UV's together in the UV editor (see the GIF below, the collar's edges are moving the torso's edges in the UV editor upon being vertex-welded together...)

Then again, my borders / shells seem to be showing up as separated in the Perspective view despite being welded together in the UV editor.

In general, I will heed your advice because I'm noticing that if I just fix up my topology, I reduce a lot of the warping around the collar. I'm literally just fixing the low, applying a Smooth - 3 levels and then seeing how warped the collar gets. And I'm remembering how controlled my low poly will need to be to reduce this intense buckling around the collar, I guess. Equidistant polygons, controlled edge loops, poles not near problem areas-- these are things I need to pay attention to.


Still wondering if it's the UV editor thing though... I guess that's normal? I'm kind of a UV newbie, so welded UV's is something I've never seen before.

1 HR LATER
I'm very certain it's a topology thing by this point, yeah, but like, I'm wondering if I can just keep the collar separate? I've added more control loops around the collar and it's becoming a nightmare to terminate them. Maybe that's what I should have done from the beginning-- keep the collar separate, make it as controlled of a subd edge loop flow as I can, subdivide, and then have the low poly be its own thing. But that would kind of miss the point of the entire projection and I'd have to work around that, seeing as my projection includes the collar.

I'll select the polys around the collar from my decimated mesh, separate them, and just work without the collar, and then project my separate collar mesh onto the collar for its detail (whatever detail that may be), and just call it a day, with the collar sitting on top of the shirt?

Deqa

Never mind, I'm getting a gradual reduction of the tearing around the collar by making the points around the collar more equidistant as is known in the technicalities of subd-mastery. It's reducing the tearing. Thanks for the advice @Kanni3d

Kanni3d

There ya go! Yeah, no harm in keeping things extremely low and blocky for the sake of evenly spaced, and equal topology. Get it all welded  and evenly spaced once morphed at a low resolution, then sub-d and project (don't sub-d first, morph, then project)

Deqa

@Kanni3d
Ya, I also noticed I had exported the decimated mesh from marvelous with huge bumping around the collar / shoulder too... so that definitely was, ahem, problematic for the projection