"Carlo A. Bertelli (Charta s.r.l.)" <carlo.berte...@gmail.com> writes:
> The GeoJSON Specification (RFC 7946) mandates the use of WGS84: > > The coordinate reference system for all GeoJSON coordinates is a >> geographic coordinate reference system, using the World Geodetic >> System 1984 (WGS 84) [WGS84 >> <https://datatracker.ietf.org/doc/html/rfc7946#ref-WGS84>] datum, with >> longitude and latitude units >> of decimal degrees. > > (chapter 4) > > OAPIF can use GeoJSON (very often) and in this case using another reference > system is not allowed, but it can also use GML level 0 or level 2 and in > these cases there is no limit to what CRS you can use. Yes, but either Because geojson can only use WGS84, it is a deficient format, and unsuitable for anyhthing where accuracy at the 2m level matters. or Because geojson in practice is widely observed to have datum tags, one can and should take the view that there is an error in the geojson format spscification and treat it as geojson+ that allows specifying crs. I personally hold the latter view. However, if one is dealing with tools that don't honor crs in geojson, agreed that one has to hold the first view. An example follows (hand redacted, may be messed up) of a geojson produced from qgis/gdal, in ITRF2014 as a way to get a good transfrom from NAD83 and be sensible in the web world. i didn't do any contortions to get this; just ogr2ogr -f GeoJSON -t_srs "EPSG:7912" -s_srs "EPSG:6319" %TRAILS/BAR/invasive-points.geojson bar.gpkg invasive-points ---------------------------------------- { "type": "FeatureCollection", "name": "foo-invasive-points", "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::7912" } }, "features": [ { "type": "Feature", "properties": { "species": "bittersweet", "todo": false }, "geometry": { "type": "Point", "coordinates": [ -71.5, 42.5, 80 ] } }, ] }
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