package net.sf.openrocket.util;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import org.junit.Test;
public class GeodeticComputationStrategyTest {
@Test
public void testSpericalAddCoordinate() {
double arcmin = (1.0 / 60.0);
double arcsec = (1.0 / (60.0 * 60.0));
double lat1 = 50.0 + 3 * arcmin + 59 * arcsec;
double lon1 = -1.0 * (5 + 42 * arcmin + 53 * arcsec); //W
double lat2 = 58 + 38 * arcmin + 38 * arcsec;
double lon2 = -1.0 * (3 + 4 * arcmin + 12 * arcsec);
double range = 968.9 * 1000.0;
double bearing = (9.0 + 7 * arcmin + 11 * arcsec) * (Math.PI / 180.0);
Coordinate coord = new Coordinate(range * Math.sin(bearing), range * Math.cos(bearing), 1000.0);
WorldCoordinate wc = new WorldCoordinate(lat1, lon1, 0.0);
wc = GeodeticComputationStrategy.SPHERICAL.addCoordinate(wc, coord);
//System.out.println(wc.getLatitudeDeg());
//System.out.println(lat2);
//System.out.println(wc.getLongitudeDeg());
//System.out.println(lon2);
assertEquals(lat2, wc.getLatitudeDeg(), 0.001);
assertEquals(lon2, wc.getLongitudeDeg(), 0.001);
assertEquals(1000.0, wc.getAltitude(), 0.0);
}
@Test
public void testAddCoordinates() {
double min = 1 / 60.0;
double sec = 1 / 3600.0;
// Test zero movement
//System.out.println("\nTesting zero movement");
testAddCoordinate(50.0, 20.0, 0, 123, 50.0, 20.0, false);
/*
* These example values have been computed using the calculator at
* http://www.movable-type.co.uk/scripts/latlong.html
*/
// Long distance NE over England, crosses Greenwich meridian
// 50 03N 005 42W to 58 38N 003 04E is 1109km at 027 16'07"
//System.out.println("\nTesting 1109km NE over England");
testAddCoordinate(50 + 3 * min, -5 - 42 * min, 1109000, 27 + 16 * min + 7 * sec, 58 + 38 * min, 3 + 4 * min, false);
// SW over Brazil
// -10N -60E to -11N -61E is 155.9km at 224 25'34"
//System.out.println("\nTesting 155km SW over Brazil");
testAddCoordinate(-10, -60, 155900, 224 + 25 * min + 34 * sec, -11, -61, true);
// NW over the 180 meridian
// 63N -179E to 63 01N 179E is 100.9km at 271 56'34"
//System.out.println("\nTesting 100km NW over 180 meridian");
testAddCoordinate(63, -179, 100900, 271 + 56 * min + 34 * sec, 63 + 1 * min, 179, true);
// NE near the north pole
// 89 50N 0E to 89 45N 175E is 46.29 km at 003 00'01"
//System.out.println("\nTesting 46km NE near north pole");
testAddCoordinate(89 + 50 * min, 0, 46290, 3 + 0 * min + 1 * sec, 89 + 45 * min, 175, false);
// S directly over south pole
// -89 50N 12E to -89 45N 192E is 46.33km at 180 00'00"
//System.out.println("\nTesting 46km directly over south pole ");
testAddCoordinate(-89 - 50 * min, 12, 46330, 180, -89 - 45 * min, -168, false);
}
private void testAddCoordinate(double initialLatitude, double initialLongitude, double distance, double bearing,
double finalLatitude, double finalLongitude, boolean testFlat) {
double tolerance;
bearing = Math.toRadians(bearing);
// positive X is EAST, positive Y is NORTH
double deltaX = distance * Math.sin(bearing);
double deltaY = distance * Math.cos(bearing);
Coordinate coord = new Coordinate(deltaX, deltaY, 1000.0);
WorldCoordinate wc = new WorldCoordinate(initialLatitude, initialLongitude, 0.0);
// Test SPHERICAL
tolerance = 0.0015 * distance / 111325;
//System.out.println("\nSpherical tolerance: " + tolerance);
WorldCoordinate result = GeodeticComputationStrategy.SPHERICAL.addCoordinate(wc, coord);
//System.out.println("Difference Lat: " + Math.abs(finalLatitude - result.getLatitudeDeg()));
//System.out.println("Difference Lon: " + Math.abs(finalLongitude - result.getLongitudeDeg()));
assertEquals(finalLatitude, result.getLatitudeDeg(), tolerance);
assertEquals(finalLongitude, result.getLongitudeDeg(), tolerance);
assertEquals(1000.0, result.getAltitude(), 0.0);
// Test WGS84
/*
* Note: Since the example values are computed using a spherical earth approximation,
* the WGS84 method will have significantly larger errors. A tolerance of 1% accommodates
* all cases except the NE flight near the north pole, where the ellipsoidal effect is
* the greatest.
*/
tolerance = 0.04 * distance / 111325;
//System.out.println("\nWGS84 tolerance: " + tolerance);
result = GeodeticComputationStrategy.WGS84.addCoordinate(wc, coord);
//System.out.println("Difference Lat: " + Math.abs(finalLatitude - result.getLatitudeDeg()));
//System.out.println("Difference Lon: " + Math.abs(finalLongitude - result.getLongitudeDeg()));
assertEquals(finalLatitude, result.getLatitudeDeg(), tolerance);
assertEquals(finalLongitude, result.getLongitudeDeg(), tolerance);
assertEquals(1000.0, result.getAltitude(), 0.0);
// Test FLAT
if (testFlat) {
tolerance = 0.02 * distance / 111325;
//System.out.println("\nFlat tolerance: " + tolerance);
result = GeodeticComputationStrategy.FLAT.addCoordinate(wc, coord);
//System.out.println("Difference Lat: " + Math.abs(finalLatitude - result.getLatitudeDeg()));
//System.out.println("Difference Lon: " + Math.abs(finalLongitude - result.getLongitudeDeg()));
assertEquals(finalLatitude, result.getLatitudeDeg(), tolerance);
assertEquals(finalLongitude, result.getLongitudeDeg(), tolerance);
assertEquals(1000.0, result.getAltitude(), 0.0);
}
}
@Test
public void testSpericalGetCoriolisAcceleration() {
// For positive latitude and rotational velocity, a movement due east results in an acceleration due south
Coordinate velocity = new Coordinate(-1000, 0, 0);
WorldCoordinate wc = new WorldCoordinate(45, 0, 0);
double north_accel = GeodeticComputationStrategy.SPHERICAL.getCoriolisAcceleration(wc, velocity).y;
//System.out.println("North accel " + north_accel);
assertTrue(north_accel < 0.0);
}
}