Minutes from 49th OpenVDB TSC meeting, May 14th, 2020, (EDT)

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

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

Regrets: *Peter* C.

Agenda:

1) Confirm quorum
2) Secretary
3) Fixing CI Builds
4) OpenVDB Houdini / Houdini Utils library
5) VDB Blur with Constant Tiles
6) AX Update
7) VDB SOP vs VDB Create SOP
8) VDB Grid Types
9) Next Meeting


1) Quorum was confirmed.

2) Secretary was Nick Avramoussis

3) Fixing CI Builds

The VDB CI was broken due to vcpkg updates. Dan to fix with a new PR. We
currently don't receive notifications if the CI fails and there are no cron
jobs. Dan to investigate these. It was noted that the vcpkg and homebrew
installations are volatile as they are not locked down to particular
dependencies. Ideally we'd have VFX platform style images across all OS's,
with "latest" CI representing the current style. There exists another PR #708
which also fixes the windows builds and looks to improve them.

4) OpenVDB Houdini / Houdini Utils library

Dan, proposal to merge the directory structure of of these two "libraries". The
separation was introduced by DW to help manage internal vs external source code.
Note VDB View also perform a similar build step (where headers are copied into a
temporary location). Discussion tabled until DW representatives are available.

5) VDB Blur with Constant Tiles

Jeff, bug reports in mantra due to strange "voxel" artifacts on blurred VDBs
which contained active constant tiles and therefore do not blur across node
boundaries. Ideal solution would be to only voxelize tiles which are guaranteed
to be affected. Ticket created to represent this work OVDB-143. Nick, explicit
calls to voxelize would assist in the short term even with the memory side
effects.

6) AX Update

Plan to have AX exist as a feature branch week beginning 18th May. Blocked on
two CMake PRs, #708 and a future CMake change to FindOpenVDB.

7) VDB SOP vs VDB Create SOP

Last outstanding SOP with discrepancies with Side FX's custom implementation.
Jeff is aware and will look to upstream.

8) VDB Grid Types

Nick, discussion around the VDB math library and VDB's default registered grid
types. AX aims to support a subset of its implemented types on VDB types but
it's not clear which of these types should be supported. For example, AX support
Vec4 point attributes but only Quat attributes are registered. This unveils a
further issue with grid/point types which are equivalent but cannot be
represented without using the explicit math implementation. This relates to
previous discussion about introducing runtime grid types and possible changes to
the VDB math library. Questions around which grid types should be registered and
how to better allow conversion from compatible types. To be discussed further at
future meeting.

9) Next Meeting

May 21st 2020. 2pm-3pm EDT (GMT-4).
