scripted volumegrid creation in 3.6 - process to load a single vdb and have the object set to the correct dimensions? Also any hints on speed / memory?

[joconnell]

Heya folks,

Doing some cloud tests on a new show and I'm using a library of houdini vdb files. We're doing a falling from space type of shot so I'm looking at the scripting of volume grid creation. Doing a simple maxscript creation of a grid and setting it's rendinput parameter to a file path of a vdb doesn't load a preview or set the grid to the dimensions of it's input so I'm wondering what's the process of getting it to update? On a manual load we get a prompt to ask us how to set values depending on where the vdb file came from which I'm sure is playing a big part. If I have a manually created grid I can swap the rendinput property and it'll update fine but if I wanted to load in a few hundred caches it'd be great to script it.

On a second note, we're testing this against another app which is very low in overheads for vdbs but not as nice looking but it'd require a second pass. Due to the amount visible in the shot I'd say we'll have some large memory overheads and we'll potentially be going from far away to close up - any hints besides things like step size that could keep the overheads down with thousands of vdbs?

Cheers!

John

[georgi.zhekov]

Hey,

It should be quite easy for the scripting part. It's best if you get a latest stable build though as we have added scripting functionality to load a render preset via Maxscript.

The script should be something like this:

VRayVolumeGrid ()
select $VRayVolumeGrid001
$.inpathraw = "Path\Test_###.vdb"
$.rendinput = "Path\Test_###.vdb"
$.usrchmap = "2,density;1,temperature;4,vel.x;5,vel.y;6,vel .z;"
$.loadRenderPreset "Path\Test_preset.tpr"

In your case you probably missed the usrchmap - it maps the Houdini channels to the V-Ray ones. 1 is temperature, 2 is smoke, 3 is fuel, 4,5,6 is velocity.

As for the memory optimization - I can't think of something special.

Cheers,

[joconnell]

Georgi you're a superstar. Our pipeline guy should be back in today so I'll get on the nightlies - much appreciated!