Geographic Information Systems

djangopythondatabase

Storing and querying data that has a position. The database side is small - PostGIS does most of it - and the real work is in coordinate systems, projections and tiling.

Storage

Coordinate systems

The thing that bites first. A coordinate pair means nothing without knowing its reference system.

  • WGS 84 (EPSG:4326) - “World Geodetic System 1984, used in GPS”. A geographic system: latitude and longitude in degrees, not metres.
  • NTF (Paris) / Lambert zone II (EPSG:27572) - a projected French system in metres, Lambert Conic Conformal, introduced in 1972. Still turns up in older French datasets.
  • EPSG.io - look up any system by code.
  • PyProj - Python bindings to PROJ, for converting between them.

Vector tiles

Mapping and display

  • Folium - Python data onto Leaflet maps, works inside Jupyter. See Jupyter.
  • GeoDjango - the spatial framework bundled with Django. See Django.

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