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VDB surface & surcface transforms don't match

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Hi people...


I got some serious vdb issues, where i got some vdb combining, tweaking,,,combining with other poly to vdb , etc. I have some xfroms on the geom before it gets converted to  vdb and combined.

It goes well for a while, i make keyframes on the xforms...and at some point on the vdb combine, the xforms stuff up and move out of position.

It seems not to like xfroms up the chain, pre vdb conversion.

I do get some odd warnings on some of the VDB combine,  i was getting is a 'mismatch surface & surface value mismatch (0.025 & 0.075)' when both A&B vdbs are 0.025, (but gets fixed with a re sample before going in to the vdb combine on both A& B


I also get a warning on 'surface & surface transforms don't match' on the vdb combine that stuffs up my transforms.

Pain! I would try to do all my geo transforms then save an alembic and load back without extra xforms, but i do need to line this up to the millimeter, and I can't due to things going off .....


I am runnning 14.0.395


thanks in advance !

Edited by octavio

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Hard to say without the scene. Throw together a small simple example where the problem occurs.

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Here is a scene, simplified, but still displaying the misalignment






Hey Octavio!


It doesnt work because you need to turn resample on always when there is a combine operation between two level set with different xform or different voxel size, so you have to resample one of the two for the aligment to take place.




Edited by Pazuzu

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Interesting that it would jump out like that. Anyway, lots of problems here. First, to the left you have a voxel size of 0.025, to the right you have 0.020. Ontop of that you have turned off "Resample", so it tries to combine two different volumes without resampling and it freaks out. Since the voxels probably won't line up perfectly that is a problem. Second, you are using Add and Subtract operations on your VDB Combines - while it may look alright to start with, invisible stuff happen with the values of the SDF. You want to use the "SDF Union/Intersection/Difference".


The different resolutions is however less important if you use the correct SDF operations, as well as using resampling.

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