native Houdini volume union does not work?!

[catchyid]

Hi,

I want to combine different volumes into one single volume. If I use native houdini volumes, I get bad results, plz see attached (used both volumemix and volumemerge). However, If I use VDBs + vdb combine, I get good results. Is this normal OR I am doing something wrong?

volumes_union.hip

[coltonmil]

Hey catchyID,

It looks like the problem is coming from the volume bounds.

If you override the volume bounds on the iso offset SOP it fixes the clipping problem.

That's a short-term fix for now. I'm trying to figure out a more intuitive and procedural way to resize the bounds to prevent clipping

Edit:

If you merge the volumes together then feed that into a volume SOP (making sure the name attribute is density) and volume merge that (into the left input) with each of the respective volumes before your final volume merge/mix that will automatically set the bounds of the volumes.

Edited January 26, 2018 by coltonmil

[catchyid]

Thanks You are correct. I think it's a bug, don't need to worry about a fix. Another thing, have you noticed that that bottom sphere after isooffset seems has some noise? i.e. it's not a clear fog like the top one? Once more thanks for your help

[coltonmil]

You can adjust the ray intersect settings in the construction tab to get better results. It should be noted that the top piece is actually giving somewhat incorrect results. It should be displaying more as a shell than a solid object, but the error is working in your favor in this case  

Using closed geo should give you better results overall.

[catchyid]

Alright, really appreciate your help, thanks