Adding distance to a GPS coordinate

Question

I\'m trying to generate some points at random distances away from a fixed point using GPS.

How can I add distance in meters to a GPS coordinate? I\'ve looked at UTM

Answer 1

This code splits the line between two coordinates in n segments. Replace the delta calculation by your fixed distance

 @Override
public void split(Coordinates p1, Coordinates p2, int segments) {
    double φ1 = Math.toRadians(p1.getLat());
    double λ1 = Math.toRadians(p1.getLon());
    double φ2 = Math.toRadians(p2.getLat());
    double λ2 = Math.toRadians(p2.getLon());


    double xDelta = (φ2 - φ1) / segments;
    double yDelta = (λ2 - λ1) / segments;
    for (int i = 0; i < segments; i++){
        double x = φ1 + i * xDelta;
        double y = λ1 + i * yDelta;
        double xc = Math.toDegrees(x);
        double yc = Math.toDegrees(y);
        System.out.println(xc+","+yc);
    }
}

Answer 2

If you want to go east or north or west or south you can use this:

@SuppressLint("DefaultLocale")
public static double go_mock_loc(double xx_lat,double xx_long,double xx_dinstance,String Direction)
{
//  double xx_lat= 45.815005; 
//  double xx_long= 15.978501;

//  int xx_dinstance=500;

    int equator_circumference=6371000;
    int polar_circumference=6356800;

    double m_per_deg_long =  360 / polar_circumference;
    double rad_lat=(xx_lat* (Math.PI) / 180);
    double m_per_deg_lat = 360 / ( Math.cos(rad_lat) * equator_circumference);

    double deg_diff_long = xx_dinstance * m_per_deg_long;
    double deg_diff_lat  = xx_dinstance * m_per_deg_lat; 


    double xx_north_lat = xx_lat + deg_diff_long;
    //double xx_north_long= xx_long;
    double xx_south_lat = xx_lat - deg_diff_long;
    //double xx_south_long= xx_long;

    //double xx_east_lat = xx_lat;
    double xx_east_long= xx_long + deg_diff_lat;  
    //double xx_west_lat = xx_lat;
    double xx_west_long= xx_long - deg_diff_lat;

    if (Direction.toUpperCase().contains("NORTH")) {
        return xx_north_lat;
    } else if (Direction.toUpperCase().contains("SOUTH"))
    {
        return xx_south_lat;
    } else if (Direction.toUpperCase().contains("EAST"))
    {
        return xx_east_long;
    } else if (Direction.toUpperCase().contains("WEST"))
    {
        return xx_west_long;
    }
    else 
        return 0; 

}

Answer 3

To take a square I'm using this:

 private double[] getBoundingBox(final double pLatitude, final double pLongitude, final int pDistanceInMeters) {

    final double[] boundingBox = new double[4];

    final double latRadian = Math.toRadians(pLatitude);

    final double degLatKm = 110.574235;
    final double degLongKm = 110.572833 * Math.cos(latRadian);
    final double deltaLat = pDistanceInMeters / 1000.0 / degLatKm;
    final double deltaLong = pDistanceInMeters / 1000.0 / degLongKm;

    final double minLat = pLatitude - deltaLat;
    final double minLong = pLongitude - deltaLong;
    final double maxLat = pLatitude + deltaLat;
    final double maxLong = pLongitude + deltaLong;

    boundingBox[0] = minLat;
    boundingBox[1] = minLong;
    boundingBox[2] = maxLat;
    boundingBox[3] = maxLong;

    return boundingBox;
}

This returns an array with 4 coordinates, with them you can make a square with your original point in center.

Answer 4

• P0(lat0,lon0) : initial position (unit : degrees)
• dx,dy : random offsets from your initial position in meters

You can use an approximation to compute the position of the randomized position:

 lat = lat0 + (180/pi)*(dy/6378137)
 lon = lon0 + (180/pi)*(dx/6378137)/cos(lat0)

This is quite precise as long as the random distance offset is below 10-100 km

Edit: of course in Java Math.cos() expects radians so do use Math.cos(Math.PI/180.0*lat0) if lat0 is in degrees as assumed above.

Answer 5

A detailed outline is given at http://www.movable-type.co.uk/scripts/latlong.html.

If you, somewhere, need to interconvert longitude/latitude to UTM coordinates (the ones used in GPS) you may want to have a look at http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.htm