Is there a way to use volume based collision using SOPs without resamp

[magneto]

Hi,

 

I am using Volume based RBD collisions by specifying a proxy volume using SOPs, but the only option I see to use that proxy is Volume Sample which resamples the incoming volume, right?

 

Is there a way to avoid resampling and use the SOP volume as is?

 

 

Thanks

[Guest tar]

When I use the Deforming Object shelf tool and cache out the files in Sops, then it's read instantaneously in Dops

[magneto]

Thanks. The deforming object only reads the geometry of the object, but for the collisions are still governed by the Volume Sample option, no? That was my understanding. So if you have a very fine collision mesh, for example, then having the same resolution will require a fine resample value in DOPs, and thus cause slower cooking.

[Guest tar]

No, with 'Volume Sample' divisions are completely ignored. The 'collision mesh' is, from the manual:

 

Volume Sample

The divisions are ignored in this mode, instead they are computed from the first volume or VDB primitive in the geometry.

[anim]

just be aware that prior to H14 Volume Sample was still resampling VDB volumes, so you had to convert them to regular sdf volumes to avoid that

but if you are using H14, then you should be fine

just note that Deforming Object shelf tool, links Division Size of Static Object with Voxel Size of Collision Source, so it may seem that Static Object is resampling the volume by tweaking Division Size, however it's actually changing actual volume that is referenced in Proxy Volume 

[magneto]

Thanks guys. I tried to read Geometry/Volume which is the collision (?) into SOPs and it took 90 seconds. I MMB'ed the node and it was a regular volume. So I thought H14 had to convert VDB into a regular volume and as such cause a massive slowdown.

[Guest tar]

To clarify you should be able to have the collision volume read almost as fast in DOPs as in Sops, once you have cached the volume.  Try with the 'Deform Object' shelf tool.

 

Make sure not to turn on 'Collision Guide' on the Static Object/Collisions/RBD/Volume tab, as turning this on seemingly makes 'SDF Representation' rebuild the volume and slow right down.