[gdal-dev] Report on GEOS maintenance grant

[Sean Gillies]

Thank you for the write up, Dan! I appreciate what you've done for the
project and community. The outcome of the grant is beyond my expectations,
for sure.

On Mon, Feb 27, 2023 at 7:35 AM Daniel Baston <dbaston at gmail.com> wrote:

> Hi All,
>
> As February comes to a close, I’m winding down the GEOS maintenance work
> that the GDAL PSC funded in 2022 [1]. I appreciate the opportunity to do
> this work and am especially thankful to those who reported issues, reviewed
> pull requests, or participated in discussions about this work.
>
> For anyone who’s interested, I wanted to share a few of the highlights
> from my perspective.
>
> New functionality: GEOS now supports reading, writing, and overlay of
> geometries with an M dimension. I added a number of C API utility functions
> requested by client library developers: GEOSLineSubstring,
> GEOSEqualsIdentical, and thread/context-specific interrupt handlers. I also
> brought in clustering algorithms such as DBSCAN that were previously only
> available in PostGIS.
>
> Performance enhancements: I found some nice performance wins in key GEOS
> algorithms such as geometry intersection testing (GEOSIntersects and
> GEOSPreparedIntersects), distance (GEOSPreparedDistance and
> GEOSPreparedDistanceWithin) and buffering complex geometries. There are
> also some gains in core internal classes such as CoordinateSequence and
> STRtree that deliver across-the-board gains.
>
> Project maintenance. I was able to simplify our CI setup by removing the
> use of Azure and AppVeyor services and bringing the associated environments
> into GitHub Actions, write a harness for performance testing and
> visualization, and perform code cleanup such as migrating from raw to
> managed pointers in key classes. I resolved a number of long-standing bug
> reports with WKT input/output, geometry simplification, and
> crashes/incorrect results from multiple algorithms in edge cases such as
> empty geometry inputs.
>
> Not everything panned out, or at least not yet. Something we’ve wanted in
> GEOS for a long time is the ability to create a GEOS geometry directly from
> an external memory buffer, such as a PostGIS LWGEOM or a GDAL OGRGeometry
> (“zero-copy”). I added experimental support for this, but so far I
> haven’t found a case where it offers much performance benefit.
>
> Dan
>
> [1] https://lists.osgeo.org/pipermail/gdal-dev/2022-February/055433.html
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-- 
Sean Gillies
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