Hi everyone

I have some issue to get my vel works properly, if someone may help it would be awesome.

1) Just a simple ripple wit wrangle converted to SDF

2) I 've Built a volume using VDB from poly, then Added cloud noise etc... Then build a vel with a VDB analysis with a custom value vel. Then I've combined my velocity fields into a vector3 field using the scalar to vector sop

3)Then I am trying Velocity Field in a Volume VOP (problem here i guess)

4. I am trying to Push the Density with VDB Advect I connected my original density VDB to the first input of the VDB Advect node, then plugged the velocity VDB coming from the Volume VOP into the second input. I set the advection method to MacCormack (you can also use Semi-Lagrangian) to push the density using the velocity field. My problem is here or inside the Volume vop. I get an error on the advect: (Unrecognized velocity grid type)

{{{The reason I am trying to use this way it is because if an another way i subtract my ripple density to my cloud density with a volume wrangle it does not look realistic, Then maybe better to trying to push the voxel directly, The final result could be a wavy cloud on large scale cloud.}}}

Thank you

{{IN the video It is the volume wrangle not the one I am trying to acchieve and i am not satisfy with that way.}}

Hi,

You need to merge all the fields you intend to modify before applying any changes.

In the VDB Advect SOP, make sure to explicitly select the velocity field you want to use.

Inside the Volume VOP, you're using a fit with both source values set to 0, which will always return 0.

Also, keep in mind that the order of operations matters in VOPs, especially when mixing floats and vectors. You were multiplying a float by a vector and getting a float as a result, then plugging that into a vector field—this will just repeat the float across all components.

Lastly, if you're sampling from a field at the current position, you can just use a Bind VOP instead of using Volume Sample VOPs.

you can also have a look at Volume Deform SOP that way you can directly deform your cloudscape with your ripple deformer if that's the look you are after