[OSGeo-Standards] Activity report w.r.t my OGC Standards membership slot

Even Rouault even.rouault at spatialys.com
Thu Mar 5 00:14:20 PST 2020


Some words about my use of my OGC Standards membership slot. I've been involved the past
year with the GeoTIFF and CRS SWG.

On the GeoTIFF front, things are calming down now that GeoTIFF 1.1 has been approved as a
OGC standard. GeoTIFF 1.1 support has been implemented in libgeotiff master (to be 1.6.0)
and GDAL master (to be 3.1.0). The possibility of further work as GeoTIFF 1.2 or 2.0 has been
raised, but there doesn't seem to be immediate interest/need for that. There have also been
some discussions about what to do with Cloud Optimized GeoTIFF, like a best practice document
or something like that, but not sure something concrete will emerge from that.

On the CRS front, the revisions of Abstract Topic 2 and WKT CRS (WKT:2019) were adopted
last year, and no major work on them is likely in the near future. PROJ 6 has implemented them.

There are now discussions about the possible standardization of a format to convey geodetic grids
(that is datasets like NTv2/.gsb for horizontal datum adjustmenet, or .gtx for geoid models). Those
discussions resurfaced just at the very moment where the PROJ team was starting a new development
to use TIFF and GeoTIFF as a standardized format, in a profile we called Geodetic TIFF grids (GTG).
This effort has culminated with the release of PROJ 7 at the beginning of this month, and the
creation of a Content Delivery Network with 242 datasets to date available at https://cdn.proj.org.

We presented this work yesterday to the CRS SWG with the following slide deck:

Reception for now has been rather mild from the SWG to be honest, with apparent preference
from other members of the SWG for netCDF or HDF based formats, but at least we've shown leadership
by creating a spec and delivering a working implementation in records time :-)

We do have seen interest from a few geodetic agencies part with the PROJ community, and we'd
like to see more to be aware of this work. So do not hesitate to spread the word around you.

A few other relevant links regarding this topic:
- https://proj.org/community/rfc/rfc-4.html : motivations and discussion about pros & cons of various formats
- https://proj.org/specifications/geodetictiffgrids.html : the specification of the GTG profile
- https://cdn.proj.org : where the grids are, and as a bonus, a small map demonstrating Javascript client-side use of GeoTIFF
- https://github.com/OSGeo/PROJ-data/tree/master/grid_tools : tools & documentation to generate GTG.


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