I think this bug must on V-Ray’s end because the Field_Texmap works perfectly in everything else I’ve tried it in, but after reporting it to Bobo I thought I’d upload it here too since you guys collaborate sometimes.
The max file is very simple. A single VDB is written out with a density of 1. Volumegrid reads this VDB fine, and when you render you get a box. If you modulate the smoke with a 3D noise map, it works as expected - black areas of the 3D noise have no density while white have complete density. When I use a Field_Texmap to modulate the density instead, it renders black. Not sure if it’s a coordinates thing but never noticed it in any other plugin or Max standard feature before.
The max file is written out in 2016 and if you look at the two volume grids it should be pretty straight forward what’s happening. I’ve posted this on Chaos group’s forum too.
VolumeGrid_bug_when_using_FieldTexmap.rar (59.6 KB)