Vellum collision detection is overall very good, except when a pesky animator does something silly like move an arm through the torso or some other kind of interpenetration (the camera can't see it so it's ok, right?). Once a bit of cloth gets stuck inside the collision geo, it can be very difficult to get out. If it does get out, sometimes the cloth will act strangely in that area. I made a VDB based network setup that tries to push the cloth back out that works OK in most cases, but it's slow and kind of a hack.

Other cloth systems I have used (nCloth, Syflex) seem to handle this kind of issue a little better.

What do you folks do when your vellum cloth gets stuck in some geo (just making sure i'm not missing something)?

Thanks,
Karl

You can try running your Geo through quick Soft Target constrained Vellum Sim to resolve the collisions, assuming your starting pose is not penetrating

tamte
You can try running your Geo through quick Soft Target constrained Vellum Sim to resolve the collisions, assuming your starting pose is not penetrating

This saved me a big headache. I ran the collision geo through the solve with high substeps to resolve collisions and used that. Best part is that because the collisions are resolved dynamically there is not pinching as the pscale will always leave a small gap for the vellum geo to occupy after the fact.

Thanks for this.

tamte
You can try running your Geo through quick Soft Target constrained Vellum Sim to resolve the collisions, assuming your starting pose is not penetrating

Tomas,
So you're saying turn all of the collision geometry into soft bodies with a pin to target vellum constraint turned on and cache the sim of each part so if any of the parts collide or attempt to penetrate the solve will push them apart. With a certain amount of thickness on each part there will be a gap between the penetrating pieces.

Is this what you mean by a Soft Target Vellum Sim? I just want to make sure I understand what you are referring to.

yes, pretty much
it should still be pretty stiff for the collider to follow the original animation faithfully
similar to what Carbon does https://www.numerion-software.com/index.php/products/carbon-plugins/carbon-cloth/advanced-features/carbon-morph [www.numerion-software.com]

you can literally do it just for problematic areas and usually it's enough to run it as a separate sim and then use cached result for your main vellum sim
but you can of course have it as a part of main vellum sim if you want some mutual interaction

Awesome! Thank you.