'The specified input does not represent a valid geography instance' exception when using SqlGeographyBuilder

Question

I\'ve written a small application that reads in from a series of KML files and then converts them into the Microsoft.SqlServer.Types.SqlGeography type using the

Answer 1

I had this same error, but it turned out to be a polygon ring orientation problem. A simple matter of flipping the order of the coordinate arrays solved the problem.

To illustrate, this fails with the above error:

 select geography::STGeomFromText ('Polygon  ( (10 10, 10 20, 20 20, 20 10, 10 10))',4326)

whereas this works:

 select geography::STGeomFromText ('Polygon  ( (10 10, 20 10, 20 20, 10 20, 10 10))',4326)

Note that I'm not flipping the x,y pairs within a point, I am flipping the order of the entire point array (e.g. {pt1, pt2, pt3, pt4, pt5} becomes {pt5, pt4, pt3, pt2, pt1}