How to make VDB smooth? (VDB from polygon)

[yjcnbnbnb200]

I use VDB from polygon to convert my geometry to VDB, but the VDB is very sharp and seems losing smooth group, like we use unique point in Facet, how can I get a smooth VDB?

 

My geometry:

 

 

VDB:

 

Edited June 23, 2015 by yjcnbnbnb200

[br1]

What about adding a vdbsmooth ?

[yjcnbnbnb200]

What about adding a vdbsmooth ?

 

To be honest, I tried but not visible help, instead of fix the sharp egdes on VDB, it bring more circles and loops to VDB.

[pbarua]

Smooth your geometry using subdivide.

[Follyx]

I tink subdivide wont work cause there no vertices and no points  in a VDB object. Wont work.

You can do a VDB smooth and convert it back to polygons. In any case you loose the origin topo.

If the VDB is not urgently neccessary for your network process, try another way.

 

 

I'm not sure (please anyone correct me if I'm wrong):

As VDB's are a mathematic model of your origin geo (similiar to NURBS), the edges will be interpreted as (tadaa) edges ;-). So between 2 Polys i.e. on a sphere.the edge have to be the highest area. I think there is no way to smooth it out with a technique similiar to smoothing groups in max cause its "just" a equalization of different light bouncing points, wheras your problem is based upon "real" geometry. Try to lower the voxel size in your "vdb from poly" to i.e 0.005 and you will see the edges very sharp. As smaller the voxels wich "bathe" the geo, as sharper are not coplanar objects; here edges.

 

If you just want to stop the overload of points in your object, try to work with packed primitives.

 

What do you want to achieve?

.

Edited June 26, 2015 by Follyx

[pbarua]

I tink subdivide wont work cause there no vertices and no points  in a VDB object. Wont work.

You can do a VDB smooth and convert it back to polygons. In any case you loose the origin topo.

If the VDB is not urgently neccessary for your network process, try another way.

What do you want to achieve?

.

I mean to subdivide before converting to vdb.

[Follyx]

ah sorry, my fault.

Yep, before converting works depending on the requirements.

[yjcnbnbnb200]

I tink subdivide wont work cause there no vertices and no points  in a VDB object. Wont work.

You can do a VDB smooth and convert it back to polygons. In any case you loose the origin topo.

If the VDB is not urgently neccessary for your network process, try another way.

 

 

I'm not sure (please anyone correct me if I'm wrong):

As VDB's are a mathematic model of your origin geo (similiar to splines), the edges will be interpreted as (tadaa) edges ;-). So between 2 Polys i.e. on a sphere.the edge have to be the highest area. I think there is no way to smooth it out with a technique similiar to smoothing groups in max cause its "just" a equalization of different light bouncing points, wheras your problem is based upon "real" geometry. Try to lower the voxel size in your "vdb from poly" to i.e 0.005 and you will see the edges very sharp. As smaller the voxels wich "bathe" the geo, as sharper are not coplanar objects; here edges.

 

If you just want to stop the overhaul of points in your object, try to work with packed primitives.

 

What do you want to achieve?

.

 

Yes you are right. Subdiv is the best way for now.

[legomir]

You can use VDB Sooth SDF node with Gaussian method. Quick scane:

quick_smooth_sdf.hip

[CiaranM]

Looks like you've hit the Nyquist limit. i.e. you're sampling the polygon geometry at a frequency higher than the details of the geometry itself. This oversampling means you won't get smooth interpolation across the SDF, because you're matching the source geometry too closely. Try increasing the voxel size.

[yjcnbnbnb200]

You can use VDB Sooth SDF node with Gaussian method. Quick scane:

 

Cool thanks. It works. What is the different between VDB smooth and VDB smooth SDF?

[yjcnbnbnb200]

Looks like you've hit the Nyquist limit. i.e. you're sampling the polygon geometry at a frequency higher than the details of the geometry itself. This oversampling means you won't get smooth interpolation across the SDF, because you're matching the source geometry too closely. Try increasing the voxel size.

 

Yes for high detail it convert like what you said I thought.

[legomir]

VDB smooth doesn't respect the SDF values of volume primitive 

[yjcnbnbnb200]

VDB smooth doesn't respect the SDF values of volume primitive 

 

Hard to understand, I only know SDF represent interior and exterior part of surface field.

 

[Follyx]

and all the inbetween

[lukeiamyourfather]

I use VDB from polygon to convert my geometry to VDB, but the VDB is very sharp and seems losing smooth group, like we use unique point in Facet, how can I get a smooth VDB?

 

My geometry:

 

geo.jpg

 

VDB:

 

vdb.jpg

 

The polygon sphere looks smooth because it has smoothed normals but smoothed normals don't translate into more polygons or smoother geometry. The geometry you see showing through on the VDB is exactly the geometry of the polygon. If you want the VDB to appear smooth then give it smoother geometry to start with (subdivided, higher frequency, etc.).

[yjcnbnbnb200]

The polygon sphere looks smooth because it has smoothed normals but smoothed normals don't translate into more polygons or smoother geometry. The geometry you see showing through on the VDB is exactly the geometry of the polygon. If you want the VDB to appear smooth then give it smoother geometry to start with (subdivided, higher frequency, etc.).

 

Thanks!