Darafei, A Geographic 3D CRS is a CRS, that is based on a geodetic reference frame (geodetic datum), and has a coordinate system with 3 axis: latitude, longitude and ellipsoidal height. For example EPSG:4979 is the code for the Geographic 3D CRS corresponding to "WGS 84" (EPSG:4326 is the corresponding Geographic 2D CRS).
This is what is described in OGC 08-015r2 "Abstract Specification Topic 2 Spatial referencing by coordinates" https://portal.opengeospatial.org/files/?artifact_id=39049 in "B.1.2.1 Principal subtypes of coordinate reference system" a) under the older term of "geodetic CRS using 3D ellipsoidal coodinates". The newer revision of this document (expected for public release in the next weeks/months) will use the term "geographic 3D CRS". Even > Hello, > > I would like to learn more about geographic 3D CRS. There is ad-hoc > solution in PostGIS ("geography") to handle 3D geographies, and I would > like to learn about alternative ways of signaling that calculations are to > be done on curved surface. > > On Wed, Jan 9, 2019 at 6:23 PM Even Rouault <even.roua...@spatialys.com> > > wrote: > > Hi, > > > > RFC 73 "Integration of PROJ6 for WKT2, late binding capabilities, > > time-support > > and unified CRS database" is available for your review at: > > > > https://trac.osgeo.org/gdal/wiki/rfc73_proj6_wkt2_srsbarn > > > > The proposed implementation is at: > > https://github.com/OSGeo/gdal/pull/1185 > > > > Even > > > > -- > > Spatialys - Geospatial professional services > > http://www.spatialys.com > > _______________________________________________ > > gdal-dev mailing list > > gdal-dev@lists.osgeo.org > > https://lists.osgeo.org/mailman/listinfo/gdal-dev -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
