SQL Spatial polygon inside out

Question

I am allowing users to draw a polygon in Silverlight by clicking to draw. Then I loop through the points, convert them to longitude and latitude and then save to SQL (in a

Answer 1

That is a common concept within geospatial geography data types, a polygon is defined by a number of vertices and the edges between those vertices. However, you have to be able to distinguish between what is inside and outside of the polygon. This is done by the system assuming that one side of the edge will always be defining the inside (Different standards use left side or right side)

In one direction you have drawn a small circle, in the other direction you have drawn a sphere that encompasses the entire world, except for a small circle. The latter would tend to break geographic limits and raise an exception.

If you consider trying to draw a doughnut, you have 2 polygons and have to have the points in a clockwise / anti-clockwise pattern, to define the 'hole' within the centre.