Hey all! First post here. My studio is trying to implement the 5.3 VDB feature into our pipeline and I am working on integrating shot vfx from Houdini into UE5 using the new VDB feature.
After a bit of forum/youtube scouring I was able to suss out the common “gotchas” with VDB import. Mainly:
World orientation: R:90,0,0, S: 1, -1, 1
VDB Scale SEEMS based on voxel size. Maybe someone can confirm this. Exporting a VDB with a voxel size of 1 from Houdini seems to transfer to UE5 with no scale change upon import. Voxel 0.1 will be 10x bigger and Voxel 10 will be 10x smaller upon import.
Now, the BIGGEST issue I’m having right now is with pivot
Testing out a single VDB frame, it seems like UE5 finds the center of the volume grid and uses that as a pivot to place the grid at UE5’s origin. Assuming this is what’s actually happening, it’s easy enough for me to do the same thing in houdini to determine the offset and reverse it. When testing this, the VDB seems to snap back into the correct location.
However…I am unfortunately working with VDB sequences and I am unable to figure out how Unreal is determining the center of the entire sequence in order to place it at the origin. I thought it would be the first frame of the sequence but that doesn’t seem to be the case.
If anyone is able to shed any light on how UE5 is handling any of this that would be spectacular! It’s currently our primary roadblock for this pipeline.
(A note: My VDBs pivots in Houdini are already at the origin so if there’s a way to force ue5 to just respect that pivot as opposed to creating a new one based on the grid’s center that could solve the issue)
Thanks in advance!