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90okm

VDB volume data from attribute

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Hi !

i'm trying to get volume data from points attribute

pls see the attached picture 

in this case i set an attribute to some value and want it to be sambled into new VDB volume.

it works like surface "wrapped" around my points (red area). and it's empty inside, although there are points inside with the attribute set to positive non-zero value

btw it works fine when i set vdbfromparticles SOP to Fog VDB - it fills all volume where points exist

 

Is it possible to sample any arbitary attribute into VDB like Fog VDB option does?  

lncS00Z.png 

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Unfortunately NO!

the default parameters produce the same effect

as you can see the inner area is empty  although i have points there  

c02U1m6.png

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You create a surface vdb which creates necessary data on the surface only by definition. But to simplify the process you could use a fluidSource sop which seems to fill the interior.

Edited by haggi

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Hi ! sorry , but i have not managed to get nice volume data from points into VDB !

Take a look at this picture ! There is the 3x3 grid (9 points with float attribute)

These 9 points are sampled into volumes

In the case of standart volumes everything goes fine (volume slice on the right)

But in the case of VDB volumes it seems like hollow circles , i.e. there is no any data within the radius of the point, just like this is a surface (not type of a Fog) 

Maybe "additional VDB primitives" means SURFACE type only ?

Are there any ways to get the same volume data in VDB as it's been done with standart volumes ?

there is the hip file in attachment

vdbvol.png

vdbfromattrib.hip

Edited by 90okm

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the help on vdbfromparticles states: "You can generate additional VDB primitives that store the values of point attributes. Only voxels near the points will be set.
So I guess you are right that it behaves like a surface VDB.

anyway here's a scene that uses rasterizepoints and VDB so it gives the same result as the standard volume. (i did a quick performance comparison and at least at that resolution the standard method is twice as fast)

dm_vdbfromattrib.hip

Edited by 3dome

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