turf-concave

turf concave module

turf.concave(points, maxEdge, units)

Takes a set of Point|points and returns a concave hull polygon.

Internally, this uses turf-tin to generate geometries.

Parameters

parameter	type	description
points	FeatureCollection.<Point>	input points
maxEdge	Number	the size of an edge necessary for part of the hull to become concave (in miles)
units	String	used for maxEdge distance (miles or kilometers)

Example

var points = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [-63.601226, 44.642643]
      }
    }, {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [-63.591442, 44.651436]
      }
    }, {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [-63.580799, 44.648749]
      }
    }, {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [-63.573589, 44.641788]
      }
    }, {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [-63.587665, 44.64533]
      }
    }, {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Point",
        "coordinates": [-63.595218, 44.64765]
      }
    }
  ]
};

var hull = turf.concave(points, 1, 'miles');

var resultFeatures = points.features.concat(hull);
var result = {
  "type": "FeatureCollection",
  "features": resultFeatures
};

//=result

Returns Feature.<Polygon>, a concave hull

Installation

Requires nodejs.

$ npm install turf-concave

Tests

$ npm test