Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
/*!
* JavaScript function to calculate the destination point given start point latitude / longitude (numeric degrees), bearing (numeric degrees) and distance (in m).
*
* Original scripts by Chris Veness
* Taken from http://movable-type.co.uk/scripts/latlong-vincenty-direct.html and optimized / cleaned up by Mathias Bynens <http://mathiasbynens.be/>
* Based on the Vincenty direct formula by T. Vincenty, “Direct and Inverse Solutions of Geodesics on the Ellipsoid with application of nested equations”, Survey Review, vol XXII no 176, 1975 <http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf>
*/
function toRad(n) {
return n * Math.PI / 180;
};
function toDeg(n) {
return n * 180 / Math.PI;
};
function destVincenty(lat1, lon1, brng, dist) {
var a = 6378137,
b = 6356752.3142,
f = 1 / 298.257223563, // WGS-84 ellipsiod
s = dist,
alpha1 = toRad(brng),
sinAlpha1 = Math.sin(alpha1),
cosAlpha1 = Math.cos(alpha1),
tanU1 = (1 - f) * Math.tan(toRad(lat1)),
cosU1 = 1 / Math.sqrt((1 + tanU1 * tanU1)), sinU1 = tanU1 * cosU1,
sigma1 = Math.atan2(tanU1, cosAlpha1),
sinAlpha = cosU1 * sinAlpha1,
cosSqAlpha = 1 - sinAlpha * sinAlpha,
uSq = cosSqAlpha * (a * a - b * b) / (b * b),
A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq))),
B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq))),
sigma = s / (b * A),
sigmaP = 2 * Math.PI;
while (Math.abs(sigma - sigmaP) > 1e-12) {
var cos2SigmaM = Math.cos(2 * sigma1 + sigma),
sinSigma = Math.sin(sigma),
cosSigma = Math.cos(sigma),
deltaSigma = B * sinSigma * (cos2SigmaM + B / 4 * (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) - B / 6 * cos2SigmaM * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM)));
sigmaP = sigma;
sigma = s / (b * A) + deltaSigma;
};
var tmp = sinU1 * sinSigma - cosU1 * cosSigma * cosAlpha1,
lat2 = Math.atan2(sinU1 * cosSigma + cosU1 * sinSigma * cosAlpha1, (1 - f) * Math.sqrt(sinAlpha * sinAlpha + tmp * tmp)),
lambda = Math.atan2(sinSigma * sinAlpha1, cosU1 * cosSigma - sinU1 * sinSigma * cosAlpha1),
C = f / 16 * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha)),
L = lambda - (1 - C) * f * sinAlpha * (sigma + C * sinSigma * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM))),
revAz = Math.atan2(sinAlpha, -tmp); // final bearing
return new LatLon(toDeg(lat2), lon1 + toDeg(L));
};
/*!
* JavaScript function to calculate the geodetic distance between two points specified by latitude/longitude using the Vincenty inverse formula for ellipsoids.
*
* Original scripts by Chris Veness
* Taken from http://movable-type.co.uk/scripts/latlong-vincenty.html and optimized / cleaned up by Mathias Bynens <http://mathiasbynens.be/>
* Based on the Vincenty direct formula by T. Vincenty, “Direct and Inverse Solutions of Geodesics on the Ellipsoid with application of nested equations”, Survey Review, vol XXII no 176, 1975 <http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf>
*
* @param {Number} lat1, lon1: first point in decimal degrees
* @param {Number} lat2, lon2: second point in decimal degrees
* @returns {Number} distance in metres between points
*/
function toRad(n) {
return n * Math.PI / 180;
};
function distVincenty(lat1, lon1, lat2, lon2) {
var a = 6378137,
b = 6356752.3142,
f = 1 / 298.257223563, // WGS-84 ellipsoid params
L = toRad(lon2-lon1),
U1 = Math.atan((1 - f) * Math.tan(toRad(lat1))),
U2 = Math.atan((1 - f) * Math.tan(toRad(lat2))),
sinU1 = Math.sin(U1),
cosU1 = Math.cos(U1),
sinU2 = Math.sin(U2),
cosU2 = Math.cos(U2),
lambda = L,
lambdaP,
iterLimit = 100;
do {
var sinLambda = Math.sin(lambda),
cosLambda = Math.cos(lambda),
sinSigma = Math.sqrt((cosU2 * sinLambda) * (cosU2 * sinLambda) + (cosU1 * sinU2 - sinU1 * cosU2 * cosLambda) * (cosU1 * sinU2 - sinU1 * cosU2 * cosLambda));
if (0 === sinSigma) {
return 0; // co-incident points
};
var cosSigma = sinU1 * sinU2 + cosU1 * cosU2 * cosLambda,
sigma = Math.atan2(sinSigma, cosSigma),
sinAlpha = cosU1 * cosU2 * sinLambda / sinSigma,
cosSqAlpha = 1 - sinAlpha * sinAlpha,
cos2SigmaM = cosSigma - 2 * sinU1 * sinU2 / cosSqAlpha,
C = f / 16 * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha));
if (isNaN(cos2SigmaM)) {
cos2SigmaM = 0; // equatorial line: cosSqAlpha = 0 (§6)
};
lambdaP = lambda;
lambda = L + (1 - C) * f * sinAlpha * (sigma + C * sinSigma * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)));
} while (Math.abs(lambda - lambdaP) > 1e-12 && --iterLimit > 0);
if (!iterLimit) {
return NaN; // formula failed to converge
};
var uSq = cosSqAlpha * (a * a - b * b) / (b * b),
A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq))),
B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq))),
deltaSigma = B * sinSigma * (cos2SigmaM + B / 4 * (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) - B / 6 * cos2SigmaM * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM))),
s = b * A * (sigma - deltaSigma);
return s.toFixed(3); // round to 1mm precision
};
@sp-suresh

This comment has been minimized.

Copy link

sp-suresh commented Sep 27, 2018

Where I can find LatLon function?
I ran the code in the browser console and it was throwing that error

@omonk

This comment has been minimized.

Copy link

omonk commented Nov 17, 2018

Where I can find LatLon function?
I ran the code in the browser console and it was throwing that error

I found you can just change that line to

return {
    lat: toDeg(lat2),
    lng: lon1 + toDeg(L),
  };

From this: https://www.movable-type.co.uk/scripts/latlong.html

@uday-brainium

This comment has been minimized.

Copy link

uday-brainium commented Jan 31, 2019

toRad() is not a function

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.