Dmitriy Zub

This is a solved issue. I want to document it for someone who possibly encounters it in the future.

SideFX team, if there's an option to improve the error message, it would be a blessing

Context:
- Substance Painter to Houdini USD workflow
- UDIMs
- Karma render

Error messages:
- libpng error: bad adaptive filter value
- libpng error: IDAT: invalid block type



Writing error message and a picture since it will better be indexed in Google search.

Solution:
- delete exported textures from Substance Painter
- export textures again
- optional: Render menu at the top -> update textures [www.sidefx.com] | Perspective -> Reset Karma XPU (or Shift+P)

I somehow understood that it's related to textures after reading through this and searching occurrences of libpng: https://www.sidefx.com/docs/hdk/png_8h_source.html [www.sidefx.com]

Why it happened (my guess)
Substance Painter exported 1 UDIM tile texture cropped i.e. half of the texture was black and only half of the top part was with texture. And Karma didn't know what to do about it. Although the Painter export message said, "export finished successfully".

All the best

A note for Googlers if you're using MTLX.

If you DON'T want imported texture (MTLX Image node) to tile:
- change "Address Mode" U and V parameters to constant. By default, it's set to periodic which means - tiling.

If you want to scale, offset, or rotate, here's my approach (MTLX Geometry Property value node fetches st(UVs in USD) value from geomprop param):

Mário Domingos
I want to randomly assign a different material to each piece

Hey Mario, possibly you're looking for a Material Variation LOP node [www.sidefx.com].

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