Question about coordRefSys and compound-CRS

[jratike80]

I am not sure if this is the right repository to ask, but is it possible to define in coordRefSys a compound CRS that does not have an EPSG code? I speak only about Spatial compound coordinate reference systems (vertical + height) without complexity of time.

For example ETRS89 / TM35FIN(N,E) + N2000 height has a code EPSG:3903
but a similar ETRS89 / TM35FIN(E,N) + N2000 height does not have a code.
The Proj library recognizes compound CRS from concatenated codes, as for the latter example
EPSG:3067+3900

The standard https://docs.ogc.org/as/18-005r4/18-005r4.html#36 supports compound crs.

The discussion about crs-compound in opengeospatial/architecture-dwg#29 may be related.

The question in this issue is related opengeospatial/ogcapi-features#357

[cportele]

Compounds CRSs where each component CRS has a URI can be specified.

Example using CURIEs: "coordRefSys": ["[EPSG:3067]", "[EPSG:3900]"].

See https://docs.ogc.org/DRAFTS/21-045.html#_reference_system_values.

[jratike80]

How about OGCFeat? Is it possible to announce EPSG:3067+3900 as a storageCrs? What would be the syntax if plain EPSG:3067 is expressed as
"storageCrs" : "http://www.opengis.net/def/crs/EPSG/0/3067"?

[cportele]

No, that is currently not possible and requires an update to Features Part 2. In hindsight, we should have supported such a capability already in v1.0.

[jratike80]

Would you mind creating an enhancement issue for Part 2? I am not lazy but I feel that you know better what to write into the description.

[cportele]

Done, see opengeospatial/ogcapi-features#864. I am closing the issue here.