Open source geospatial coordinate sytem libraries are being revised


A "GDAL Coordinate System Barn Raising" has raised $144,000 to enable improvements to coordinate system libraries needed for the GDAL, PROJ, libgeotiff, PostGIS, and Spatialite open source toolchain. Support came from 25 players in the geospatial market including SAFE Software and ESRI, Boundless, Azavea, LINZ, MapBox, Riegl, Radiant Solutions, and others.

The objective of this effort is to provide GDAL, PROJ, and libgeotiff with modern capabilities including support for the updated OGC well-known text standard WKT2, replacing CSV tables with SQLite-based databases, not requiring projection transformations to pivot through WGS84, and preparing for the new North American datum NATRF2022 and NAPGD2022 which I blogged about previously.

The use of a SQLite-based database for coordinate systems definitions will allow projects to add more capability, transition custom project coordinate systems to something more universally consumable, and promote interoperability between different software.

Well-known text (WKT) is a text markup language for spatial reference systems of spatial objects and transformations between spatial reference systems. The updated standard, known as "WKT 2", was adopted by the Open Geospatial Consortium and ISO in 2015. OGC WKT2 fixes longstanding interoperability coordinate system definition discrepancies and contains tools for describing time-dependent coordinate reference systems.  Several countries are updating their geodetic infrastructure to include time-dependent coordinate systems. For example, Australia and the United States are adapting time-dependent coordinate systems in 2020 and 2022, respectively. The familiar NAD83 and NAVD88 in North America are being replaced by NATRF2022 and NAPGD2022, and the industry will have to adapt to these changes.

The new libraries provide for higher accuracy transformations between coordinate systems that avoid transforming everything through WGS84 and eliminate the extra steps that this entails.

Thanks to Dale Lutz of SAFE Software for pointing me to this during a chat at GeoAlberta 2018.