
Hi, I'd like to use the distance functions between two lat lon points but get distance in degrees rather than a more convenient distance such as metres. How do I use the SharpMap libraries to get the distance expressed as a linear unit between two points
expressed as an angular unit? Thanks for any pointers.... Gavin



Hi,
if you have the distance in degrees you can convert those to metres by yourself using the following methods:
/// <summary>
/// Degrees to radians.
/// </summary>
/// <param name="degree">Value in degrees.</param>
/// <returns>Value in radians.</returns>
private static double DegreesToRadians(double degree)
{
return degree * Math.PI / 180.0;
}
/// <summary>
/// Converts radians to meters.
/// </summary>
/// <param name="radians">Value in radians.</param>
/// <returns>Value in meters.</returns>
private static double RadiansToMeters(double radians)
{
// there are 1852 meters in a nautical mile
// Radians to Nautical Miles: radians * 60 * 180 / Math.PI
return 1852 * (radians * 10800 / Math.PI);
}
Hope that helps.
Jo



Thanks! I've also just discovered this page
http://www.movabletype.co.uk/scripts/latlong.html
with the Haversine formula that seems to give results.
Thanks for the quick response,
Gavin

