Forums Technical Discussion Vellum Hair problem

Vellum Hair problem

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keithlynch_81
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Hi, I'm struggling to work out what I'm doing wrong with Vellum hair attached to an animated FBX. The hair is acting really erratically.



Has anyone had any success with Vellum and animated FBX and could take a look at my issue please?

Thanks!
Edited by keithlynch_81 - Feb. 5, 2019 10:11:03

Attachments:
Yeti01.mp4 (8.5 MB)
Yeti1.hiplc (825.2 KB)

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Midasssilver
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Can't troubleshoot a scene if the fbx isn't provided.
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keithlynch_81
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Ah whoops! Sorry about that. Have attached it below. Thanks

Attachments:
Thriller Part 2.fbx (7.0 MB)

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Midasssilver
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I simplified your scene a lot, so I could make sense of what was happening. Sorry, I'm not familiar with all the new vellum nodes, but I found a pretty serious issue early in your chain. You are scattering points for your hair on the surface of the fbx, which changes every frame. Because of this, your hair guides get completely out of wack. I changed the hairgen mode to per point, instead of on surface, and things appear to have been fixed.

Attachments:
Yeti2.hiplc (667.7 KB)

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keithlynch_81
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thank you so much for taking the time to do that! It's massively appreciated. A few hours back someone on the facebook group thought there might be an issue in regarding the scattering of points. I clearly need to go back and learn more of the basics of how the hair gen system works!

Thanks again!
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keithlynch_81
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Hi, I'm getting this error when I open your file:



and getting this result:



guessing that looks different on your computer?

Attachments:
Warning.jpg (133.1 KB)
HairIssue01.jpg (767.2 KB)

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Midasssilver
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The main problem you are seeing here is your collision geometry and the length of your guides. If your hair guides interpenetrate the collision geometry at the first frame, then they will get stuck inside. One fix would involve scaling your collision geometry (the fbx) up over time, so that there are no interpenetrations at the start. Then as the collision geo grows to full size, the guides will collide against the geometry properly. I've attached a new hip that demonstrates how there are no obvious issues with the collision geometry disabled.

Attachments:
Yeti3.hiplc (667.6 KB)

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