calculating Lat and Long from Bearing and Distance

Question

I\'m having a hard time wrapping my head around some Trigonometry. I am trying to deduce a destination latitude and longitude from a start lat and log and distance and bear

Answer 1

if anyone needs a function that calculates point coordinates from other point moved by some distance, below is the working code. For me, it's just moving a point by some distance.

import static java.lang.Math.*;

void movePoint(double latitude, double longitude, double distanceInMetres, double bearing) {
    double brngRad = toRadians(bearing);
    double latRad = toRadians(latitude);
    double lonRad = toRadians(longitude);
    int earthRadiusInMetres = 6371000;
    double distFrac = distanceInMetres / earthRadiusInMetres;

    double latitudeResult = asin(sin(latRad) * cos(distFrac) + cos(latRad) * sin(distFrac) * cos(brngRad));
    double a = atan2(sin(brngRad) * sin(distFrac) * cos(latRad), cos(distFrac) - sin(latRad) * sin(latitudeResult));
    double longitudeResult = (lonRad + a + 3 * PI) % (2 * PI) - PI;

    System.out.println("latitude: " + toDegrees(latitudeResult) + ", longitude: " + toDegrees(longitudeResult));
}

• latitude, longitude - entry point coordinates
• distanceInMetres - distance that you want to move the point by
• bearing - an angle, direction towards which you want to move the point. 0 is towards the North, 90 - East, 180 - South, 270 - West. And all between, i.e. 45 is North East.
• earthRadiusInMetres - Earth radius in metres.

You can change the radius to 6371 if you want to have the input in kilometres or to miles if you want to have input in miles.

Answer 2

Your problem is on your first line.

Try

double dist = 150.0 / 6371.0;

The reason is that 150/6371 gets calculated as 0, because it performs integer division (rather than floating point division). This is true even though the result is being stored in a double. You can force floating point division by making one of the two numbers a floating point literal.