Minutes from 120-th OpenVDB TSC meeting, February 8th, 2022, (EDT)

Attendees: *Ken* M., *Jeff* L., *Andre* P, *Nick* A., *Rich* J.

Additional Attendees: Sebastian Gaida, Greg Hurst (United Therapeutics), Karl
Marett (UCLA), Bruce Cherniak (Intel), Kyle Wardlow

Regrets: *Dan* B.

Agenda:

1) Confirm quorum
2) Secretary
3) Forum
4) Undefined Behavior Sanitizer in Coord Hash
5) ASWF Open Source Forum March 10
6) VDB Blend
7) Next Meeting

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1) Confirm quorum

Quorum is present.

2) Secretary

Secretary is Andre Pradhana.

3) Forum

a) Issue 1301

Question about making ZLIB to be optional when using BLOSC. Nick thinks that
the solution brought up in the issue is correct, i.e. we need to get rid of
the if statement in the CMakeLists that says that if you use BLOSC then you
also need to use ZLIB.

b) PR-1282

Ken has reviewed PR-1282 and made a few suggestions. Jeff will approve the PR.
Ken will wait for the submitter to make the required changes. If, after awhile,
there is no reply from the submitter, Ken will merge the PR and will submit
another PR with his fix.

Jeff signed off this PR. Greg Hurst will test Ken's proposed fix.

4) Undefined Behavior Sanitizer in Coord Hash

Nick says that we have an undefined behavior sanitizer in VDB. There was a post
specifically static analyzer warning of undefined behavior. Nick has been trying
to fix these, primarily signed overflow. He is now asking about this issue in
Coord's hash. There is a method in the Coord class that returns hash, but it may
overflow. Jeff says that we should reinterpret_cast.

Ken proposes to fix the sanitizer and Nick will review it.

5) ASWF Open Source Forum March 10

This means Ken has to present something related to VDB

6) VDB Blend

Andre talks about VDB Blend, which is an implementation of SIGGRAPH talk by
Sony-Imageworks: Levelsets in Production: Spider-Man 3. The disadvantage of this
method is the need to have a pretty wide narrow-band level sets for it to work well.
Jeff and Ken likes the idea of doing dilation on the intersection region between
the two level sets. One may use extrapolate technique to define a meaningful
signed-distance value in this dilation region. Once this is done, we can apply
the blending method in this dilated region. Ken also mentions that he has published
a paper on this in 2002 called Level Set Surface Editing Operators. Jeff thinks that
we should have a separate SOP for VDB Blend.

7) Next Meeting

Next meeting is in one week, February 18th, 2022. 1pm-2pm EST (GMT-5).
