PL/pgSQL function for generating polygon geometry for given grid reference (specified in JHS 197). The system is also known as "UTM-lehtijako" by National Land Survey of Finland.

Run the SQL in nls_mapsheet.sql in your Postgis database. Then you can use the function nls_mapsheet, eg. SELECT 'K2311E4' AS id, nls_mapsheet('K2311E4') AS geom;

The above function assumes the input is a valid JHS 197 grid reference. To validate a string, you can use the function nls_mapsheet_isvalid.sql, eg. SELECT nls_mapsheet_isvalid('K2311E4'); -> TRUE

The file test/data.dump contains NLS supplied geometries for all 144,594 official mapsheets. To test all of them against the functions, run in repo root:

docker run --rm -v $(pwd):/nls_mapsheet postgis/postgis:13-3.1 /nls_mapsheet/test/custom-entrypoint.sh