crsgrid

Portable grid specs for any CRS: a family of CRS instances sharing one lattice, plus its domain, ID scheme and alignment to other grids. Early design stage; see brief.md.

• schema/crsgrid.schema.json: the spec, as a JSON Schema (v0.1 draft)
• examples/: grids expressed as specs: aatgrid, equi7grid, s2mgrs, nsidc-polar-stereo, rema-2m, cop30, gibs-polar
• fixtures/: conformance cases (spec + input → expected output), generated by an oracle
• tools/fixtures-aatgrid.R, tools/fixtures-s2mgrs.R: generate fixtures from the aatgrid package, and from real Sentinel-2 items plus GeographicLib; fixtures/equi7grid.json and fixtures/nsidc-polar-stereo.json are transcribed from the upstream Equi7Grid tests and the NSIDC guide; tools/fixtures-vrt.py reads REMA and COP30 tile placements from their VRTs; tools/fixtures-wmts.py reads GIBS tile matrices from WMTS capabilities
• tools/check_fixtures.py: checks a spec reproduces its fixtures using only the spec (python3 tools/check_fixtures.py fixtures/*.json; needs jsonschema, pyproj, and shapely + pyarrow for polygon domains)
• tools/lint.py: first lint pass (python3 tools/lint.py examples/*.json)
• tools/propose.py: AOI -> proposed spec, with rounding table, known-CRS check and lint (python3 tools/propose.py --bbox=143.5,148.5,-43.7,-39.5 --res 10,20,60); worked examples in examples/proposed/
• tools/align.py: are two specs aligned? (python3 tools/align.py examples/aatgrid.json examples/s2mgrs.json)
• r/: the R runtime (package crsgrid, gdalraster-based), passing every fixture; see r/README.md
• notes/: background surveys