Geometry Calculations

A set of methods that perform spatial calculations against shapes. These static methods are exposed through the Microsoft.Maps.SpatialMath.Geometry namespace.

Important Note: Many of these calculations use 2D geometry calculations with different projected planes to approximate there equivalent spatially accurate calculations. This introduces a margin of error. When testing the area calculation and comparing the results to the geography area calculation in SQL, the following differences in calculated values where observed when testing against shapes of different sizes:

If you require higher accuracy spatial calculations, create a web service and use the Microsoft SQL Server Spatial Types library. This is a .NET library that can be used on its own and doesn't require installing SQL.

Also note, there may be instances where, when visualizing results of a calculations, they look to have a larger margin of error. For instance, the calculated centroid of a 100KM line may appear to be several meters away from the line itself. The reason for this is that due to the Mercator projection of the map, “straight lines” between two locations should in fact be rendered as curved geodesic lines, however, for simplicity and performance, the map renders a geometric straight line. If you were to pass the line through the getGeodesicPath function the line and the centroid would intersect.

There is partial support for shapes which cross the anti-meridian (-180/180 degrees longitude). To help reduce "world wrap" issues, the spatial math module automatically splits result shapes along this line if they cross the anti-meridian.