/// <summary>
/// Calculate the three dimensional geodetic measurement between two positions
/// measured in reference to a specified ellipsoid.
/// This calculation is performed by first computing a new ellipsoid by expanding or contracting
/// the reference ellipsoid such that the new ellipsoid passes through the average elevation
/// of the two positions. A geodetic curve across the new ellisoid is calculated. The
/// point-to-point distance is calculated as the hypotenuse of a right triangle where the length
/// of one side is the ellipsoidal distance and the other is the difference in elevation.
/// </summary>
/// <param name="start">starting position</param>
/// <param name="end">ending position</param>
/// <returns>The geodetic measurement information to get from start to end</returns>
public GeodeticMeasurement CalculateGeodeticMeasurement(
GlobalPosition start,
GlobalPosition end)
{
// get the coordinates
var startCoords = start.Coordinates;
var endCoords = end.Coordinates;
// calculate elevation differences
var elev1 = start.Elevation;
var elev2 = end.Elevation;
var elev12 = (elev1 + elev2) / 2.0;
// calculate latitude differences
var phi1 = startCoords.Latitude.Radians;
var phi2 = endCoords.Latitude.Radians;
var phi12 = (phi1 + phi2) / 2.0;
// calculate a new ellipsoid to accommodate average elevation
var refA = ReferenceGlobe.SemiMajorAxis;
var f = ReferenceGlobe.Flattening;
var a = refA + elev12 * (1.0 + f * Math.Sin(phi12));
var ellipsoid = Ellipsoid.FromAAndF(a, f);
var geoCalc = new GeodeticCalculator(ellipsoid);
// calculate the curve at the average elevation
var averageCurve =
geoCalc.CalculateGeodeticCurve(startCoords, endCoords);
// return the measurement
return(new GeodeticMeasurement(averageCurve, elev2 - elev1));
}
public void TestFactory1()
{
var e = Ellipsoid.FromAAndF(100000, 0.01);
Assert.AreEqual(e.SemiMinorAxis, (1 - 0.01) * 100000);
Assert.AreEqual(100, e.InverseFlattening);
Assert.AreEqual(100000, e.SemiMajorAxis);
Assert.AreEqual(e.Ratio, 1.0 - 0.01);
}