Flooded Interior - Collision Geometry help

[art3mis]

Hey guys. Need some help with collision geometry for a Flip sim.

In the attached you can see the original geometry in collision source, and the resulting voxels in #2.

The geometry is sourced from external .objs that I have merged than applied a Boolean Union operation to.

Is there something else I can do to make sure the conversion to voxels works correctly?

Edited December 13, 2022 by art3mis

[dleonhardt]

The object needs thickness and it needs to be watertight.

[haggi]

You can close the geometry and use invert sign in the static collider node to use the interior only.

[ryew]

Once your mesh is thickened and watertight, you will likely need a higher voxel resolution for your collider as well - I suggest halving your collision resolution until you see proper representation of the geometry in VDB form - also cull out/down parts of any sections you don't need to collide with to reduce the calculation time.

[art3mis]

Thanks for the replies!
Tried reducing my Voxel (VDB) size in my Collision Source but didn't seem to help.
Also, when should you use Surface Collisions (Geometry) vs Volume Collisions (VDB) as your Collision Detection type?

[Atom]

With FLIP you never use surface collision, that's for RBD. FLIP always uses volume collision.

You're viewing your collision wrong. Collision is the purple color, you have to activate it under the Guides tab of the FLIP Object. What you're showing us in your screenshot is the VDB conversion. Flip converts it once more by resampling it to your particle separation value. That's what the true collider looks like and the guides tab will show you.

[art3mis]

28 minutes ago, Atom said:

With FLIP you never use surface collision, that's for RBD. FLIP always uses volume collision.

You're viewing your collision wrong. Collision is the purple color, you have to activate it under the Guides tab of the FLIP Object. What you're showing us in your screenshot is the VDB conversion. Flip converts it once more by resampling it to your particle separation value. That's what the true collider looks like and the guides tab will show you.

Thanks Atom