Minutes from 43rd OpenVDB TSC meeting, Match 19th, 2020, (GMT)

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

Additional Attendees: Bruce Chernia (Intel), Johannes Meng (Intel),
JT Nelson (Blender), Robin Rowe (Cinepaint)

Regrets: *Peter* C.

Agenda:

1) Confirm quorum
2) Secretary
3) NanoVDB
4) AX 
5) CI and GitHub Actions migration
6) Level set tracking
7) PR review
8) Roadmap
9) Next meeting

1) Quorum was confirmed.g

2) Secretary was Dan Bailey

3) NanoVDB

Ken has implemented a GPU version of OpenVDB called NanoVDB. It is currently
based on CUDA but could be re-implemented using OpenCL without too much work.
Data structures are immutable, so primary application is rendering. Ken
reporting around a 30x speedup on the GPU compared with an 88-thread CPU for
doing a naive raymarching using bundles of rays. CPU version being compared
against is not fully accelerated (ie no vectorization). It uses a binary search
for the root node which may improve performance on the CPU too.

4) AX

Nick has been working on a language spec to be shared soon. As a test
application, vdb_view has been modified to manipulate VDB grids on-the-fly using
AX.

5) CI and GitHub Actions migration

PR665 has successfully used PR re-targetting as a way of ingesting external
contributions. The default branch will be reverted back to master soon as a
result. This is a precursor to storing Houdini daily builds in the GitHub
Actions cache to sidestep any issues with secret keys.

6) Level set tracking

Level set tracking currently dilates in both directions whereas a more efficient
implementation may be to look at the direction of the moving interface and to
dilate in just one direction. Dan to investigate.

Nick has a faster, but less accurate implementation of dilation and erosion to
share for future discussion. In some cases it can be as much as 2x faster.

7) PR review

Quick review of some outstanding PRs.

8) Roadmap

Time

9) Next meeting

April 2nd 2020. 2pm-3pm EDT (GMT-4).

