I am using Proj4Projection
I have a polygon created from WKT in 4326/WGS84 from which I get a bounding box.
When I use GetDistanceTo to measure the distance from top left to top right of the bounding box I get a value of 365 metres (This is the correct value according to measuring using Goog maps)
When I create an external projection of this bounding box and again measure the top left to top right distance I get a value of 666 metres.
The external projection seems to be correct as when I add the bounding box to the feature it displays as expected on the map (Bing)
This seems like a trival piece of work so I suspect there is something basic I am missing. Why are the measurements different?
int measurementInternal = (int)Math.Round(internalBBox.UpperLeftPoint.GetDistanceTo(internalBBox.UpperRightPoint, GeographyUnit.DecimalDegree, DistanceUnit.Meter), 0, MidpointRounding.AwayFromZero);
int measurementExternal = (int)Math.Round(externalBBox.UpperLeftPoint.GetDistanceTo(externalBBox.UpperRightPoint, GeographyUnit.Meter, DistanceUnit.Meter), 0, MidpointRounding.AwayFromZero);