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bentway23

Maya not reading alembic UVs

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I've written out some simmed geo as .abc files for use in Maya. Maya will not read the UVs, but Houdini reads them just fine. The alembics have to be unpacked for them to show up in Houdini--thinking that was the problem, I ran them through an unpack node and re-wrote them, with the same results. The only Googling result I've found says that UVs have to be a point attribute for Maya to read them, but I've found no way to make that happen, as attribute promote screws them all up. How can I get the UVs to Maya? Attribute transfer (in Maya) from the original object (created in Maya) doesn't work, as the new geo is simmed and moving so the UVs would swim.

Thanks!

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Without seeing a .hip or some screenshots, a better explanation is difficult to guess. We go back and forth without issues.

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The .abc is 16GB (480-frame sim), so I can't share the alembic. Attached are screenshots of the Houdini UV viewport--the first one is the tree as it was provided by the modeler (I know, not the most elegant of UVing), seen after unpacking the .abc. The second (blown-out white one) is what happens to the UVs if I promote the UV attribute from vertex to point, which is apparently how Maya needs them. There's no UV screenshot in Maya, as Maya just doesn't see there being any UVs.

 

Screen Shot 2019-07-24 at 1.02.26 PM.png

Screen Shot 2019-07-24 at 1.02.41 PM.png

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Okay, so I've tracked down WHERE the problem seems to be, just not sure how to fix it--

First off, I backed up a bit and wrote the .abc from a previous node, which is working, UVs going fine to Maya.

This is a tree, and I have a second scene that takes the simmed/repo'd/retimed .abc and creates another version with 3,000 tiny twigs on it. Because of the camera angle and the fact that this is more for silhouette purposes, they don't have to be perfect, intersecting geo is fine, &c., so I just scattered points on the simmed tree and copy/stamped a selection of five different twigs.

Writing this straight out to alembic worked, but going into Maya it also brought in 3,001 shape nodes--one for each new twig. The solution I found was to take the geo after the copy-stamp/merge and run it through a Boolean and Convert. This made it one shape node in Maya but also apparently is what squashes the UVs.

I've tried an attribute transfer of UVs from the merge to the convert, but that doesn't seem to work--they bounce every frame.

So is there a way I can either transfer the UVs (including the original twigs' own UVs) to this version or, more probably, is there a better way to make it one shape node in Maya instead of 3,001?

node_tree.png

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Just in case anyone runs into this down the line, another forum gave me solution: The boolean/convert was squashing UVs. The trick was to create a "path" attribute on the twigs, and assemble the hierarchy in the ROP alembic. At first I created this attribute after the copy/stamp--which was fine--except the copy/stamp was set to pack the geo, which setting paths doesn't like. Unclicking "pack" did the trick.

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That's a cancer, if you have a maya render pipe, I been meet this problem so many times. if you can not see the uv in maya then promote the uv attribute from vertex level to point level. better do it before you fracture your geo.

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