Movable Type Scripts

Separator character to be used to separate degrees, minutes, seconds, and cardinal directions.

Default separator is U+202F ‘narrow no-break space’.

To change this (e.g. to empty string or full space), set Dms.separator prior to invoking formatting.

Parses string representing degrees/minutes/seconds into numeric degrees.

This is very flexible on formats, allowing signed decimal degrees, or deg-min-sec optionally suffixed by compass direction (NSEW); a variety of separators are accepted. Examples -3.62, '3 37 12W', '3°37′12′′W'.

A latitude/longitude point defines a geographic location on or above/below the earth’s surface, measured in degrees from the equator & the International Reference Meridian and in metres above the ellipsoid, and based on a given datum

As so much modern geodesy is based on WGS-84 (as used by GPS), this module includes WGS-84 ellipsoid parameters, and it has methods for converting geodetic (latitude/longitude) points to/from geocentric cartesian points; the latlon-ellipsoidal-datum and latlon-ellipsoidal-referenceframe modules provide transformation parameters for converting between historical datums and between modern reference frames.

This module is used for both trigonometric geodesy and n‐vector geodesy, and for UTM/MGRS mapping.

Latitude/longitude points on an ellipsoidal model earth, with ellipsoid parameters and methods for converting points to/from cartesian (ECEF) coordinates.

This is the core class, which will usually be used via other modules.

Creates a geodetic latitude/longitude point on a (WGS84) ellipsoidal model earth.

Parses a latitude/longitude point from a variety of formats.

Latitude & longitude (in degrees) can be supplied as two separate parameters, as a single comma-separated lat/lon string, or as a single object with { lat, lon } or GeoJSON properties.

The latitude/longitude values may be numeric or strings; they may be signed decimal or deg-min-sec (hexagesimal) suffixed by compass direction (NSEW); a variety of separators are accepted. Examples: LatLon.parse(51.4778, -0.0015) // ≡ new LatLon() LatLon.parse('51°28′40′′N, 000°00′05′′W', 17) LatLon.parse({ lat: 52.205, lon: 0.119 }, 17)

Historical geodetic datums: a latitude/longitude point defines a geographic location on (or above/below) the earth’s surface, measured in degrees from the equator and the International Reference Meridian and metres above the ellipsoid, and based on a given datum. The datum is based on a reference ellipsoid and tied to geodetic survey reference points.

Modern geodesy is generally based on the WGS84 datum (as used for instance by GPS systems), but previously various reference ellipsoids and datum references were used.

This module extends the core latlon-ellipsoidal module to include ellipsoid parameters and datum transformation parameters, and methods for converting between different (generally historical) datums.

It can be used for UK Ordnance Survey mapping (OS National Grid References are still based on the otherwise historical OSGB36 datum), as well as for historical purposes.

Creates a geodetic latitude/longitude point on an ellipsoidal model earth using a specified datum.

Datums; with associated ellipsoid, and Helmert transform parameters to convert from WGS-84 into given datum.

Note that precision of various datums will vary, and WGS-84 (original) is not defined to be accurate to better than ±1 metre. No transformation should be assumed to be accurate to better than a metre, for many datums somewhat less.

This is a small sample of commoner datums from a large set of historical datums. I will add new datums on request.

Parses various representations of latitude/longitude coordinate as per LatLonEllipsoidal.parse().

Modern geodetic reference frames: a latitude/longitude point defines a geographic location on or above/below the earth’s surface, measured in degrees from the equator and the International Reference Meridian and metres above the ellipsoid within a given terrestrial reference frame at a given epoch.

This module extends the core latlon-ellipsoidal module to include methods for converting between different reference frames.

This is scratching the surface of complexities involved in high precision geodesy, but may be of interest and/or value to those with less demanding requirements.

Creates geodetic latitude/longitude point on an ellipsoidal model earth using using a specified reference frame.

Note that while the epoch defaults to the frame reference epoch, the accuracy of ITRF realisations is meaningless without knowing the observation epoch.

Ellipsoid parameters; semi-major axis (a), semi-minor axis (b), and flattening (f).

The only ellipsoids used in modern geodesy are WGS-84 and GRS-80 (while based on differing defining parameters, the only effective difference is a 0.1mm variation in the semi-minor axis b).

14-parameter Helmert transformation parameters between (dynamic) ITRS frames, and from ITRS frames to (static) regional TRFs NAD83, ETRF2000, and GDA94.

This is a limited set of transformations; e.g. ITRF frames prior to ITRF2000 are not included. More transformations could be added on request.

Parses various representations of latitude/longitude coordinate as per LatLonEllipsoidal.parse().

Extends LatLonEllipsoidal with methods for calculating distances and bearings between points, and destination points given distances and initial bearings, accurate to within 0.5mm distance, 0.000015′′ bearing.

By default, these calculations are made on a WGS-84 ellipsoid. Geodesic calculations on other ellipsoids can be done by setting the datum of this point to make it appear as a LatLonEllipsoidal_Datum point.

An n-vector is a position representation using a (unit) vector normal to the Earth ellipsoid. Unlike latitude/longitude points, n-vectors have no singularities or discontinuities.

For many applications, n-vectors are more convenient to work with than other position representations such as latitude/longitude, earth-centred earth-fixed (ECEF) vectors, UTM coordinates, etc.

An n‐vector is a (unit) vector normal to the Earth's surface (a non-singular position representation).

For many applications, n-vectors are more convenient to work with than other position representations such as latitude/longitude, UTM coordinates, etc.

On a spherical model earth, an n‐vector is equivalent to a (normalised) earth-centred earth-fixed (ECEF) vector.

Library of geodesy functions for operations on a spherical earth model.

Includes distances, bearings, destinations, etc, for both great circle paths and rhumb lines, and other related functions.

Parses a latitude/longitude point from a variety of formats.

Latitude & longitude (in degrees) can be supplied as two separate parameters, as a single comma-separated lat/lon string, or as a single object with { lat, lon } or GeoJSON properties.

The latitude/longitude values may be numeric or strings; they may be signed decimal or deg-min-sec (hexagesimal) suffixed by compass direction (NSEW); a variety of separators are accepted. Examples: LatLon.parse(52.205, 0.119) // ≡ new LatLon() LatLon.parse('52°12′18.0′′N, 000°07′08.4′′E') LatLon.parse({ lat: 52.205, lon: 0.119 })

Military Grid Reference System (MGRS/NATO) grid references provides geocoordinate references covering the entire globe, based on UTM projections.

MGRS references comprise a grid zone designator, a 100km square identification, and an easting and northing (in metres); e.g. ‘31U DQ 48251 11932’.

Depending on requirements, some parts of the reference may be omitted (implied), and eastings/northings may be given to varying resolution.

Returns a string representation of an MGRS grid reference.

To distinguish from civilian UTM coordinate representations, no space is included within the zone/band grid zone designator.

Components are separated by spaces: for a military-style unseparated string, use Mgrs.toString().replace(/ /g, '');

Note that MGRS grid references get truncated, not rounded (unlike UTM coordinates).

Converts this Ordnance Survey grid reference easting/northing coordinate to latitude/longitude (SW corner of grid square).

While OS grid references are based on OSGB-36, the Ordnance Survey have deprecated the use of OSGB-36 for latitude/longitude coordinates (in favour of WGS-84), hence this function returns WGS-84 by default, with OSGB-36 as an option. See www.ordnancesurvey.co.uk/blog/2014/12/2.

Parses grid reference to OsGridRef object.

Accepts standard grid references (eg 'SU 387 148'), with or without whitespace separators, from two-digit references up to 10-digit references (1m ×ばつ 1m square), or fully numeric comma-separated references in metres (eg '438700,114800').

The Universal Transverse Mercator (UTM) system is a 2-dimensional Cartesian coordinate system providing locations on the surface of the Earth.

UTM is a set of 60 transverse Mercator projections, normally based on the WGS-84 ellipsoid. Within each zone, coordinates are represented as eastings and northings, measures in metres; e.g. ‘31 N 448251 5411932’.

Parses string representation of UTM coordinate.

A UTM coordinate comprises (space-separated) zone, hemisphere, easting, northing.

Returns a string representation of a UTM coordinate.

To distinguish from MGRS grid zone designators, a space is left between the zone and the hemisphere.

Note that UTM coordinates get rounded, not truncated (unlike MGRS grid references).