Delete part of Volume Cache

[wilson99]

Hi guys,

Any ideas on how to delete part of a volume cache using some soft of a bbox?
 

Image below. Using the box to delete that part of the cached volume.

 

Thanks

[rbowden]

Turn your box into a volume and use a volume mix to subtract the box from the sim.

-Ryan

volume_subtract.hip

[fathom]

that could produce negative values, no?

 

i would do a volume wrangle:

 

	f@density *= 1-volumesample(1,0,v@P);
	

convert your box into a houdini volume (NOT A VDB) and plug it into input 2.  plug your smoke volume into input 1.

Edited April 21, 2016 by fathom

[rbowden]

It could but, for something like the example he was showing he would be fine. That said, volume wrangle would be much faster and would be a much better solution.

-Ryan

Edit: Good to see you around Miles!

Edited April 21, 2016 by rbowden

[pezetko]

There is Volume Resize SOP for dense volumes that is really fast. You can fetch polygon bounding box to its second input to keep only volumes inside that box.

There is also VDB Clip for Sparse VDBs that does similar thing.

Wrangle method is good if you don't want to change your original volume's bbox.

[duongduy92]

brilliant Petr, works like charm!