local-proj

Find a projection for easy cartesian calculations, given a GeoJSON in WGS84.

Problem: you have geographic data in WGS84 of limited extent, but arbitrary location, and you need to work with the data in a cartesian system (use euclidean distance, etc.)

Solution: feed your data to local-proj, and it will hand you a suitable projection independent of geographic location

Installing

npm install --save local-proj

Example

var localProj = require('local-proj');
var geojson = [...]

var projection = localProj.find(geojson);

var cartesian = projection.forward(geojsoncoord);

To reproject your GeoJSON to the projection, you might want to look at reproject.

API

find(geojson)

Finds a local projection that is suitable for projecting the geojson to cartesian coordinates.

The returned projection is a proj4 projection object (proj4.Proj), which you can use to create transforms to and from other projections.

Note that the local coordinate system will only work as expected for datasets up to a couple of hundred kilometers in size.

Currently, the returned projection will always be a transverse mercator projection.