Geographic coordinate utilities using WGS84 datum

Installation

$ npm install wgs84-util

Methods

distanceBetween(pointA, pointB [, bearings ])

Calculate the distance between a set of GeoJSON points in meters

Uses Vincenty inverse calculation

Adapted from http://www.movable-type.co.uk/scripts/latlong-vincenty.html

Parameters

pointA: object, GeoJSON point

pointB: object, GeoJSON point

bearings: boolean, optional switch for including the bearings in degrees

Returns

number | object, distance from this point to the supplied point in meters or an object that includes distance, initial and final bearings

throws: Error, if formula failed to converge

bearingsBetween(pointA, pointB)

Convenience function for returning only the initial and final bearings between the given coordinates (forward azimuths at each point)

Parameters

pointA: object, GeoJSON point

pointB: object, GeoJSON point

Returns

object, forward azimuths (initial and final bearings) at each point in degrees

destination(point, bearing, distance)

Calculate the destination point from this point having travelled the given distance in meters on the given initial bearing

Uses Vincenty direct calculation

Adapted from http://www.movable-type.co.uk/scripts/latlong-vincenty.html

Parameters

point: object, GeoJSON point

bearing: number, initial bearing in degrees from north

distance: number, distance along bearing in meters

Returns

object, GeoJSON destination point, finalBearing

throws: Error, if formula failed to converge

degToRad(deg)

Conversion from degrees to radians

Parameters

deg: number, angle in degrees

Returns

number, angle in radians

radToDeg(rad)

Conversion from radians to degrees

Parameters

rad: number, angle in radians

Returns

number, angle in degrees

LLtoUTM(ll)

Converts a set of Longitude and Latitude coordinates to UTM using the WGS84 ellipsoid.

Parameters

ll: object, GeoJSON point representing the coordinate to be converted

Returns

object, GeoJSON feature containing the UTM value with easting, northing, zoneNumber and zoneLetter properties, and an optional accuracy property in digits. Returns null if the conversion failed.

UTMtoLL(utm)

Converts UTM coordinates to lat/long, using the WGS84 ellipsoid

Parameters

utm: object, with northing, easting, zoneNumber and zoneLetter properties. If an optional accuracy property is provided (in meters), a bounding box will be returned instead of latitude and longitude.

Returns

object, GeoJSON object containing either lat and lon values (if no accuracy was provided), or top, right, bottom and left values for the bounding box calculated according to the provided accuracy. Returns null if the conversion failed.

Running Tests

Install the development dependencies:

$ npm install

Then run the tests:

$ npm test

Code Coverage

Install the development dependencies:

$ npm install

Then run coverage

$ npm run coverage

View coverage reports

$ firefox coverage/lcov-report/index.html

Browser Bundle

$ npm run build

License

Copyright (c) 2016 Christopher Brandt

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.