Hair Guide Deform always offsets hair

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Hello! I have a groom that looks like this.


When I use the guide deform node on it, it always offsets it like this:

In this instance, I connected the rest pose into the animated skin input just to test, and I really can't understand why it offsets it in this way. I do suspect its got something to do with how I import the character using USD character import. The reason I bone deform the static mesh is because the geo is oriented downwards(imported from Blender). Any help is appreciated!

Attachments:
Undeformed_groom.png (398.2 KB)
Deformed_Hair.png (572.3 KB)
Character_Import.png (31.1 KB)

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After a lot of trial and error I found out that saving a rest attribute works. However, the rest geometry from blender is facing towards the ground, so i rotate it up, and then set the rest before rotating it back again for bone deform. This feels hacky, but it does work. Am i missing something obvious here?

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Kinda_works.png (71.6 KB)

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Apparently Blender uses a Z-up coordinate system, whereas Houdini and most(/all?) other 3D software uses a Y-up system.

I believe it is also possible to change your Houdini interface to use Z-up. Go to Edit->Preferences->3D Viewports and change the Orientation to Z-up.

You could replace the wrangle where you set the rest attribute with a Rest SOP, which does the equivalent thing.
Liesbeth Levick
Technical Director: CFX
SideFX
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