Alembic UV Problem

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Dear Forumers,

For some unknown reason the UVs won't change when operations are attempted by nodes (eg. UV Flatten) in my geo node. This is when the geo is coming from the .abc like I need.

To test, if I plug in the pig head all works normally.

Whats the problem pls?

Thanks

5D
Edited by 5D - June 11, 2021 00:10:18

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2021-06-11 (2).png (984.7 KB)

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Was it converted from polysoup to polygons first? Alembic shapes without primitive attributes unpack to polysoup primitives.
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your geo is probably a Polysoup
try appending Convert SOP after your unpack
Tomas Slancik
FX Supervisor
Method Studios, NY
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thanks. that was the problem.
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Hi. Was poly soup the precursor to pack prims? I have never used it but going from the description it seems like it is not needed any more.

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Mark Wallman
Hi. Was poly soup the precursor to pack prims? I have never used it but going from the description it seems like it is not needed any more.

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I think they were introduced around the same time. They are still useful for saving memory and for enumerating meshes. Attributes on faces become indexed by soup instead of by face allowing for removing a lot of redundancy for face attributes. Topology information is also compressed with poly soups--vertices are deduplicated where vertices have share positions/normals. With regular polygons ever vertex holds a value for vertex attributes. Although you can do similar enumeration strategies using packing, there is a performance cost to unpacking/repacking. Whereas with polysoups, the vertex/point data modification is highly performant, assuming all the vertices that are needed already exist in the soup. I think they are similar in concept to using indexed attributes in usd.
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