Work flow questions: Poly mesh to VDB to Point cloud + attribs

[GeordieM]

TL;DR: How do I transfer/create attributes from geo faces & points to VDB to a point cloud?

 

Hi all,  I'm working on some vegetation scatter tech on poly objects.  The problem is the input poly objects are non manifold and I need to cull the intersecting areas so vegetation is scattered only on the external surfaces.

 

This is my currently work flow:
Input Geo -> Poly Cap -> Convert to VDB =

Input Geo -> Poly Cap -> Convert to VDB => Merge VDBs -> Scatter points on VDB for vegetation 

 

Apart from the poly cap not being the best this works pretty well until I want to create attributes for the vegetation, some need to be sourced from the input Geo and some need to be generated.  What I was hoping to do was generate a point cloud from the VDB, then populated it with data and cache it to disk so I could do fast lookups on the data whenever I needed to spawn vegetation:

                      -> Input VDB, process volumes, write data to point cloud

 Merge VDBs -> Scatter point ----------------------------------------------------> Sample data from point cloud

 

The most simple example is I want an attribute present in the VDB/ point cloud identifying which areas were created with the poly cap so I know not to spawn points there as these would always be the back sides of the input geo.

 

I've seen in the Polygon to VDB you can create attributes, and I can see it's created a VDB for each attrib, but how to i visualize this in any way?  The Geometry Spread Sheet doesn't have a volume mode and I can't seem to get volume visualization SOP to do anything.

 

What I want is something like how the scatter SOP works where it interpolates point attribs across a polygon and assigns the interpolated value to the scatter points, but for polygon -> VDB.

 

Also, should I be skipping adding attribs to the VDB and assigning them directly to the point cloud?

 

is there a better way of doing this whole thing?

 

Thanks!

 

G

Edited June 2, 2015 by GeordieM

[acey195]

Hi Geordie,

 

Its probably easiest to just transfer the attributes after converting back to primitives/points.

so in your case the point cloud.

 

Greetings from a colleague

[Skybar]

I don't really understand what you are trying to do. Small example hip?

[GeordieM]

Haha so many colleagues

 

So the Ray sop did the trick.  I wanted to avoid adding the attribs directly to the VDB since it dubes the whole volume per attrib and I might need 15 or so attribs.   I post an example file when I'm done.

 

G