Two different VDB's effecting one main VDB body

[Mussi]

Hello all, I'm on the Houdini special ed. bus after years in Maya. Attached is not pretty but after two days I've rolled all attempts back to a baseline. Illustrated I've got VDB tubes running through a body and VDB spheres denting the same VDB body. Simply I can't get both spheres and tubes to effect the body at once and control their smoothness independently. One or the other works perfectly on the body, not both at once. The end result is convertVDB to poly. Probably over complicating this, any guidance is appreciated. Thanks!

 

[Guest tar]

Can you upload your file - if you 'freeze' the file node that geo will come with the .hip, if that's important

[Mussi]

Thanks for taking a look Marty.

 

Edited April 7, 2017 by Mussi

[Mussi]

Still going around in circles with this one. Appreciate any tips.

[Guest tar]

your 'vdbcombine5_difference1' is in error - what is meant to be plugged into the first input?

[Mussi]

Plugging in vdbfrompolygons9 from the body to vdbcombine5_difference1 will do it but that then creates 2 bodies. I've then have two bodies running in parallel in the spheres and tubes column. The only thing that comes to mind is adding and connecting a single vdbcombine (vdbintersect) from each union. Doesn't seem right though. I've tried adding a merge at the bottom after smoothing before converting to polygons but that give me two bodies overlapping.

[Guest tar]

Just seems like you want to use the mask input of the VDB Smooth. Which part do you want smoothed?

[Mussi]

I'm looking to control the smoothing of the spheres as a group and tubes as a group separately while effecting the 1 body. Specifically filter voxel radius and iterations parameters.  One smoothing node for each will work. Admittedly I'm not familiar with mask input.

[Mussi]

Hey Marty, Just a follow up. This wasn't an easy answer as first thought. It's ugly and probably the most inefficient way but it works with full control. Gotta clean up this mess a little. Thanks for the assist earlier.

[edward]

It's hard to tell from these pics and what you've told us ... But why can't you just smooth the spheres and tubes separately like in your first image, and then use vdbcombine to "merge" the spheres and tubes together? Only use Convert VDB *after* you've combined them.

[Mussi]

Hey Edward. I think that would work if you wanted to effect all the spheres and tubes as a whole. Looking back, controlling individual smooth didn't make much sense, it was the Reshape controls.  The biggest issue was getting over the idea that combine isn't really a merge when working with VDB's (merge happens earlier in the tree with geometry and accepts up to 9999 inputs). It only accepts 1 input each A & B, which dragged this out a lot more especially when you want to control 11 ReShapes individually while also not influencing neighboring VDB's such as the tubes for example.  I may be wrong but this was all trial/error/learning.

Edited April 7, 2017 by Mussi

[edward]

VDB Combine can used to take the union of all merged VDB primitives from the second input, if you set the operation to "Flatten All B into A". So you can just use Merge for all your VDB primitives and pipe them into the second input of VDB Combine. For the first input, you can just use an empty VDB of the appropriate voxel size created using the VDB SOP.

[Mussi]

This is great info Edward......it will go a long way in untangling this web. Thanks!