How do I take a VDB file from Houdini and render it with Arnold (KtoA) in Katana? @Mike Farnsworth ?
There are two kinds of VDBs that KtoA can handle: volume (density) and surface (levelset/implicit) VDBs. Once you have done your simulation or surfacing in Houdini and have exported your .vdb file, you should note which channels you have output into the file (such as field, density, velocity, etc).
Inside Katana/KtoA there are three steps you need to take:
There are additional fields on the OpenVDB nodes that are of interest, for example volume_padding to give some slack if you use positional displacement (such as noise) in your volume shader network to add detail to the volume. You can control the time/quality tradeoff with the step_scale parameter, and you can control velocity in various ways. Usually Arnold will automatically detect the velocity grid in the file, but occasionally you may need to explicitly add the velocity channel(s) to get motion blur.
hello i have the issue where i "can not get bounds for the file" when trying to read VDB sequence
I tryed ### and %03d since i have a padding of 3 and none of this is working i only can read a specific frame any help ?
The only error I is the bbox, so it not showing in the viewport, the rest work fine
Is that not an issue ? cause when you type that 'pathsmoke.'+ str(int(frame)) + '.vdb' as an expression it finds the BBox and everything looks fine but I don't understand why it does not come as default. thx for the help
This has been fixed in the latest version of KtoA; it now will take an actual asset if you have an asset system enabled in Katana, and supports file sequences.
File sequences (as selection from an asset system) has been added to KtoA as of version 2.0.7.0, so now you can do filenames like: pathsmoke.###.vdb or pathsmoke.%04d.vdb and it should substitute the frame number accordingly.
Hello, could you please upload this file or some example? I have your same problem, but in my case there appear white sprites in my viewer instead of the smoke, and I don't know how to solve it.😓
Hi, @ggarciamuriel Could you please check your material assignment and make sure it's set to use ArnoldVolumeShader?