I'm writing a web API to our GIS data, currently revamping our geocoding service. I'm creating the option for folks to specify the output type as GeoJSON so I'm trying to follow the spec. Our data is stored in nad83 datum UTM zone 12 north projection. The GeoJSON spec says to add a CRS. The wkid is 26912 but what is the OGC CRS URN?
I can understand that the OGC CRS URN is broken down into a few parts.
urn:ogc:def:crs:OGC:1.3:CRS84
urn is the identifier, ogc is the organization, def is another static deal, crs is the type (coordinate reference system), OGC is the authority, 1.3 is the version and CRS84 is the projection.
Why is the authority of utm 26912 the European Petroleum Survey Group?
Do any mapping frameworks even use this CRS name?
I want to follow the spec but it seems that more mapping frameworks are using the wkid.
http://spatialreference.org/ref/epsg/26912/
seems like the best place to get the info but they don't even list the urn. Is the GeoJSON spec just silly or what?
Why is the authority of utm 26912 the European Petroleum Survey Group?
Possibly you're thinking that the wrong way. EPSG maintain a database of projections, and assign them codes. So EPSG is the authority for a UTM projection 26912, because that is the code that EPSG has assigned to a UTM projection. ESRI or some other authority could assign the same code or a different one to the same projection definition. As long as clients know how to look up the projection identifier in the authority database we'll know where we all are