public void TestCartesianToGC()
{
// start position of test
double latStart = 47.0;
double lonStart = 11.0;
// 1 arcsec is about 30m => move in 0.3m steps along all 8 axis away from the start position
double deltaInc = 0.01 / 3600.0;
GeographicPosition pStart = new GeographicPosition(latStart, lonStart, 0);
double distance = 0;
double direction = 0;
Length gcDist = Length.Zero;
Angle gcDir;
// iterate over the 8 axis (45° increments)
for (int signIdx = 0; signIdx < 8; signIdx++)
{
double dblXSign = 1.0;
if (signIdx >= 4 && signIdx <= 6)
{
dblXSign = -1.0;
}
else if (signIdx == 3 || signIdx == 7)
{
dblXSign = 0.0;
}
double dblYSign = 1.0;
if (signIdx >= 2 && signIdx <= 4)
{
dblYSign = -1.0;
}
else if (signIdx == 1 || signIdx == 5)
{
dblYSign = 0.0;
}
// iterate in 0.3m steps (up to about 150m distance)
for (int idx = 1; idx <= 400; idx++)
{
double delta = idx * deltaInc;
GeographicPosition pEnd = new GeographicPosition(latStart + dblYSign * delta, lonStart + dblXSign * delta, 0);
InternalDistDir(pStart, pEnd, ref distance, ref direction);
GreatCircle.DistAndDir(pStart, pEnd, out gcDist, out gcDir);
// compare the two calculation methods
Assert.True(Math.Abs(distance - gcDist.Meters) < 1.0, "position accuracy less than 1m");
Assert.True(GreatCircle.AngleDifferenceSignedDegrees(direction, gcDir.Degrees) < 1.0, "direction accuracy less than 1 deg");
// calculate the endpoint with the previously calculated offsets using great circle
double dblEndLat = 0;
double dblEndLon = 0;
GreatCircle.CalcCoords(pStart.Latitude, pStart.Longitude, gcDir.Degrees, gcDist.Meters, out dblEndLat, out dblEndLon);
Assert.True(Math.Abs(dblEndLat - pEnd.Latitude) < 1.0, "GC latitude accuracy less than 1m");
Assert.True(GreatCircle.AngleDifferenceSignedDegrees(dblEndLon, pEnd.Longitude) < 1.0, "GC longitude accuracy less than 1m");
// calculate the endpoint with the previously calculated offsets using the cartesic routine
GeographicPosition pCalcEnd = InternalExtrapolatePosition(pStart, distance, direction);
double dblDeltaX = Math.Abs(pCalcEnd.Longitude - pEnd.Longitude) * GreatCircle.MetersPerDegreeLongitude;
double dblDeltaY = Math.Abs(pCalcEnd.Latitude - pEnd.Latitude) * GreatCircle.MetersPerDegreeeLatitude;
Assert.True(dblDeltaY < 1.0, "XY latitude accuracy less than 1m");
Assert.True(dblDeltaX < 1.0, "XY longitude accuracy less than 1m");
}
}
}
private static bool TestDistAndDir(double startlat, double startlon, double endlat, double endlon)
{
double dist = 0;
double dir = 0;
GreatCircle.DistAndDir(startlat, startlon, endlat, endlon, out dist, out dir);
Angle dirNormalized = Angle.FromDegrees(dir).Normalize(true);
if (endlon >= 180)
{
endlon -= 360;
}
if (endlon < -180)
{
endlon += 360;
}
Assert.True(dist < 30000000, "Distance more than 1/2 times around the earth");
Assert.True(dirNormalized.Degrees >= 0 && dirNormalized.Degrees < 360, "Angle out of bounds");
double reslat = 0;
double reslon = 0;
GreatCircle.CalcCoords(startlat, startlon, dir, dist, out reslat, out reslon);
Angle lon = Angle.FromDegrees(reslon);
lon = lon.Normalize(false);
Assert.True(reslat >= -90 && reslat <= 90, "Invalid latitude");
Assert.True(lon.Degrees > -180, $"Invalid longitude A {reslon}");
Assert.True(lon.Degrees <= 180, $"Invalid longitude B {reslon}");
double accuracy = 1E-7;
if (dist > 100000)
{
accuracy = 1E-6;
}
if (dist > 1000000)
{
accuracy = 1E-6;
}
if (dist > 10000000)
{
accuracy = 1E-5;
}
if (Math.Abs(endlat - reslat) > accuracy)
{
Console.WriteLine("Error testing: " + startlat + "/" + startlon +
" to " + endlat + "/" + endlon + " Distance: " + dist +
" Difference in lat: " + (endlat - reslat));
return(false);
}
if (GreatCircle.AngleDifferenceSignedDegrees(endlon, lon.Degrees) > accuracy)
{
Console.WriteLine("Error testing: " + startlat + "/" + startlon +
" to " + endlat + "/" + endlon + " Distance: " + dist +
" Difference in lon: " + (endlon - reslon));
return(false);
}
return(true);
}