Adding bound CRS and engineering CRS to the proj.db

[phaarnes]

Hi,

I'm exploring the possibility of adding custom CRS and transformations to the proj.db so they can be utilized with all the built-in functionality in Pyproj/Proj.

Is it possible to add:

• Bound CRS
• Engineering CRS

I assume that adding bound CRSs might not be possible, but perhaps there is a way to add engineering CRS? One challenge with engineering CRS, as I see it, is the lack of an ellipsoid, which, from my understanding, is mandatory in the geodetic_crs table in proj.db.

There exist a BoundCRS class, and engineering CRS objects can be created based on WKT2, so it should be possible.

[djhoese]

I am not the expert at this, but I have hacked my own installation in a docker container for a MapServer instance to include some custom EPSG codes by doing the following SQL query. This makes an EPSG code 930916 for the GOES-16 ABI meteorological satellite instrument's CRS:

INSERT INTO projected_crs (auth_name, code, name, description, coordinate_system_auth_name, coordinate_system_code, geodetic_crs_auth_name, geodetic_crs_code, conversion_auth_name, conversion_code, text_definition, deprecated) VALUES ('EPSG', '930916', 'GOES-16 ABI Fixed Grid', 'GOES-16 (GOES-WEST) ABI Fixed Grid in the Geostationary projection', null, null, 'EPSG', '4269', null, null, 'PROJCRS["GOES-16 ABI Fixed Grid",BASEGEOGCRS["GOES-16 ABI Fixed Grid",DATUM["North American Datum 1983",ELLIPSOID["GRS 1980",6378137,298.257222101,LENGTHUNIT["metre",1]],ID["EPSG",6269]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8901]]],CONVERSION["unknown",METHOD["Geostationary Satellite (Sweep X)"],PARAMETER["Longitude of natural origin",-75,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8802]],PARAMETER["Satellite Height",35786023,LENGTHUNIT["metre",1,ID["EPSG",9001]]],PARAMETER["False easting",0,LENGTHUNIT["metre",1],ID["EPSG",8806]],PARAMETER["False northing",0,LENGTHUNIT["metre",1],ID["EPSG",8807]]],CS[Cartesian,2],AXIS["(E)",east,ORDER[1],LENGTHUNIT["metre",1,ID["EPSG",9001]]],AXIS["(N)",north,ORDER[2],LENGTHUNIT["metre",1,ID["EPSG",9001]]]]', 0);

Most of this was determined by using my IDE (pycharm) to look at the tables in the PROJ database and reverse engineer/hack what values I could add. If you can find the equivalent table/rows for what you want to do in the database then something similar should work.

[phaarnes]

Okay, thanks! I will test this out for both engineering CRS and bound CRS. For the bound CRS, the BoundCRS class could probably be used to create OGC WKT 2 to store in the database. I'll update this conversation with the results.