Minutes from 50th OpenVDB TSC meeting, May 21st, 2020, (EDT)

Happy 50th meeting anniversary!

Attendees: *Nick* A., *Jeff* L., *Ken* M., *Dan* B.

Additional Attendees: 

JT Nelson (Blender), Bruce Chernia (Intel), Andre Pradhana (DWA),
Peter Cheng (DWA)

Regrets: *Peter* C.

Agenda:

1) Confirm quorum

Quorom is present

2) Secretary

Jeff Lait

3) Forum

Question about multires; appears to be addressed.

4) houdini_utils

DWA will look into whether this can be integrated into a single directory or
not.  Can we separate off the houdini_utils code as a pure VDB support tool?
Can DWA fork their internal houdini_utils from the VDB version so we don't
have to keep targeting a separate directory?

5) Ken's workload

a) Fast Sweeping PR

b) Benchmark for Multi-Res

Can we get the funding from ASWF to do the benchmark component?  Potential targets of the funding are busy for a month or so.  Can we get the ASWF dedicated resources moved to VDB?  Send a letter out?

DWA is planning the Gas Net Slice Exchange as current priority.

Ken's first priority is Fast Sweeping.  We'll re-address the benchmark
requirements in another month.

6) Siggraph

We discussed what things might be possible to annouce for Siggraph.

Fast Sweeping.  Has a lot of functionality not exposed in the sop.  Some should be in a new SOP, such as extrapolation.  Others, such as renormalizing, should fold into existing SOPs.  Best plan is to get it in the tool level before worrying too much about these decisions.

AX: hopefully?  Depends on amount of time for reviewing.  Some PRs need reviewing now!

Sharpening.

VDB Activate.  Is in now.

VDB Merge.  Dan is hopeful.

7) Website

We tend to forget that PRs are there.  We should add a code owner so the website triggers code reviewers for all of the TSC.  None of the download links work now that we moved from nexus to artifact; and artifact is not working.  Linux foundation is investigating.

8) AX

Matches VEX Scalar promotion rules.  Have CMake PR for finding the right modules.  And AX is ready to integrate.


9) Grid Types

Becoming more frequent of an issue.

In AX we have our own types based on VDB math.  This includes matrices.  AX should be agnostic to registered VDB types.  Registration should only matter for serialization.  Any intermediate data structure should be allowed.  We should be able to make a 6-float VDB without registration.  

Clip, prune, and other grid tools defined on the tree require certain functions to exist: less than, greater than, absolute value, etc.  These don't really exist on Matrix.  Would like an agnostic grid, so matrix3 <-> float9.  And move away from math library.  So VDB_Grid::float3 rather than VDB_Grid::Vec3.  This is helped as we move more stuff from the nodes to the grids.  Should we add < for matrices?  Or add a openvdb::lessthan() that does explicit lexigraphic comparison?  The ABI means we will keep these methods for a while, so we should find a solution that doesn't require moving them out.  Matrix2 is not currently supported in AX, so the float4 is still unambiguous.  Nick will share the code needed, along with an email of what Jeff's suggestion is.  

10) Next Meeting

May 28st 2020. 2pm-3pm EDT (GMT-4).
