Glenn Dawick

GlennimusPrime

About Me

専門知識
VFX Artist
業界:
Advertising / Motion Graphics

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New Zealand
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Houdini Engine

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Recent Forum Posts

Looping USD VDB Volumes Behaving Strangely [SOLVED] 2024年6月4日19:43

Solved with some help over on the Odforce forums.


Offsetting the volume .bgeo sequence is easy enough, as long as the volume LOP Sampling Behaviour is set to the length of the .bgeo smoke cache.


Offsetting the geometry / particle .bgeo sequence has a few more steps.
The Geometry Sequence LOP requires an Import Path Prefix:


The Cache LOP should be set to Always Cache All Frames and the length of the .bgeo sequence should be set:


The Instancer LOP needs the same Prototype Primitive path that has been set on the Geometry Sequence LOP:


.hip file and small .bgeo caches attached for anyone interested.

Looping USD VDB Volumes Behaving Strangely [SOLVED] 2024年5月27日23:02

Thanks so much for all the useful information!
I have one last question regarding triggering the start frame of instanced volumes and geometry caches.

I have a working example here of a line of instanced volumes that use the point @frame attribute to explicitly read the correct cache frame using a retime instances LOP. The volumes play with offset starting times from left to right:


When I use a similar technique with geometry (animated particle burst cache) all instances play at the same time.


I've tried this technique using a reference LOP, as well as the same usd geometry cache method from above, but no luck in offsetting the start times of the geometry cache. Only the volumes.

.hipfile v05 attached

Looping USD VDB Volumes Behaving Strangely [SOLVED] 2024年5月27日16:55

Thanks npetit, that last little step has done it.

Setting the 'filter time samples' option set to 'never' in this tiny test shot is doing the trick, but I'd like to ask if this could be a bad idea to do in a very large scene with lots of long heavy volumes on a much larger scale? Just asking, as you say it's a way of optimising the output by trimming unnecessary time samples. In the case of a much larger scene, would it be better practice to first cache the volume LOP to usd with those additional time samples and then leave this 'filter time samples' at the default setting?