The GeodeticCalculator is used to perform calculations on the Geoid (i.e. on the surface of the world).
You can configure your GeodeticCalculator to work with a specific Ellipsoid (or commonly from an CoordinateReferenceSystem) and then use it to perform a number
Distance between two points
// the following code is based on JTS.orthodromicDistance( start, end, crs ) GeodeticCalculator gc = new GeodeticCalculator(crs); gc.setStartingPosition(JTS.toDirectPosition(start, crs)); gc.setDestinationPosition(JTS.toDirectPosition(end, crs)); double distance = gc.getOrthodromicDistance(); int totalmeters = (int) distance; int km = totalmeters / 1000; int meters = totalmeters - (km * 1000); float remaining_cm = (float) (distance - totalmeters) * 10000; remaining_cm = Math.round(remaining_cm); float cm = remaining_cm / 100; System.out.println("Distance = " + km + "km " + meters + "m " + cm + "cm");
Although the above shows quickly creating a DirectPosition from a JTS Coordinate; you can use the GeodedicCalculator with any two positions, internally it will transform the points as needed.
You can also generate the angle between the two points
Continuing on from the previous example:
double angle = gc.getAzimuth(); System.out.println("Angle = " + angle);
Generate location away from a point
Finally you can turn the tables and use the GeodeticCalculator to generate a point a set direction and distance away from your starting point.
GeodeticCalculator calc = new GeodeticCalculator(); // mind, this is lon/lat calc.setStartingGeographicPoint(45.4644, 9.1908); calc.setDirection(90 /* azimuth */, 200 /* distance */); Point2D dest = calc.getDestinationGeographicPoint(); System.out.println("Longitude: " + dest.getX() + " Latitude: " + dest.getY());