Closed odscjen closed 12 months ago
I had no idea that Mollweide was an ESRI specific either... it is one of the most used projection for global data, thus we should definitely allow both EPSG and ESRI.
https://epsg.io/ seems to include both EPSG and ESRI codes as a recommended source for codes. We should probably specify how to structure the codes to make it clear if it's EPSG or ESRI, i.e. so it look like "ESRI: 54009" rather than just "54009".
So update to:
"The reference co-ordinate system of this resource, using the EPSG or ESRI codes from https://epsg.io/. Provide both the scheme and the code, e.g. EPSG:4326"
Seems like there are other CRS identifier authorities besides EPSG and ERSI, e.g. OGC and IGNF, and some CRSs which are not registered with any authority, e.g. ZANGI:HBKNO15.
Other standards (e.g. PROJJSON, which is based on WKT's Identifier definition) model CRS identifiers as at least two separate fields: one for the authority and one for the identifier.
I suggest that we do the same here, e.g.
{
"coordinate_reference_system": {
"authority": "ERSI",
"id": "54009"
}
We can then have an open crs_authority codelist with codes for at least EPSG, ERSI, OGC and IGNF.
Imho this is going too deep into particular cases. I would stick to EPSG and ESRI standards from https://epsg.io This is coherent with data preparation guidelines where we are suggesting to convert rarely-used CRS to commonly-used CRS.
I'd stick to one field attribute with both authority and ID (e.g. "EPSG:4326"; "ESRI:54009"). Open crs
codelist.
I'd stick to one field attribute with both authority and ID (e.g. "EPSG:4326"; "ESRI:54009").
Agreed with this to be explicit. It's usual to include the scheme and code separated by colon in say QGS lookups for selecting spatial references. Then we also don't need a crs codelist as it is in the field.
Using a single field gives a bit less flexibility for validation. There are a few options:
If we choose either of the regex options, it will need to be explained in the field description.
Prefer 2. Use a regex to require that the string begins with either 'EPSG:' or 'ESRI:', i.e. disallow any other authorities But if it is best to have them in separate fields then let's do that.
Agree on 2. Please note it is "ESRI".
One of the draft examples takes the coodinate system from https://ghsl.jrc.ec.europa.eu/download.php?ds=bu which only appears to offer data in a coordinate system that is defined in ESRI but not EPSG (something the source itself appears to have wrong). Should we simply update the description of
Resource.coordinate_system
from "The reference co-ordinate system of this resource, using the EPSG codelist." to "The reference co-ordinate system of this resource, using the EPSG or ESRI codes."I'm not particularly fond of this solution as having a single code source is best but when even the EC's Joint Research Centre are getting confused between EPSG and ESRI maybe we need to include the possibility of both?