Cartographic Functions

This library is a simple wrapper around the Shapely and pyProj libraries that I've developed for common cartographic use cases.

Dependencies

• pyproj
• shapely

pyproj is used for geodesic calculations and projections, shapely is used to convert wgs84 coordinates into usable geometries.

Installation

Installation in a virtual environment

pyvenv venv
. ./bin/activate
pip install -r requirements.txt

Features

Note that in most cases, the WGS84 ellipsoid is assumed.

In geodesics.py

• great circle (densified) between two points
• great circle distance between two points
• great circle passing through two points and going around world
• geodesic point buffer
  • using pyproj (tracing great circle around point)
  • using Azimuthal Equidistant projection
• square point buffer from centre (lon, lat) with given edge length
• bounding box from two WGS84 corners, using great circles
• size of degree (in meters) at given latitude
• tissot indicatrix
• convert canvas extent for arbitrary CRS to densified linestring in WGS84

In cartesian.py

• create graticules (densified)
• create cartesian line (densified) between two wgs84 points

In utils.py

• dump geometry to geojson file

In units.py

• some useful constants for conversion to meters

Examples

See /test/tests.py for examples of usage.

How far can a missile reach if launched from Edinburgh if its range is 4000km?

geom = geodesic_point_buffer(-3.18907797315, 55.953326627, 2000, 4000000, Polygon)
print(geom.wkt)

What's the great circle between London Heathrow and Dubai airports?

geom = great_circle(-0.455, 51.471, 55.368, 25.250, 1000, LineString)
print(geom.wkt)

The units.py has various unit conversions into meters, e.g.

import units
# 500 nautical mile radius
geom = geodesic_point_buffer(-3.189, 55.953, 2000, 500.0 * NM, Polygon)
print(geom.wkt)