# Intersection of convex polygons on a spherical surface

There are a number of algorithms available for the intersection of two convex polygons, but I am interested in an algorithm to find the intersection of two convex polygons on the surface of a sphere, where the edges of the polygons are great circles. The polygons might be arbitrarily large (i.e. no approximation for small areas).

Is there a description of such an algorithm available? Better, is there any Python or C code out there that would do this, and has a liberal open source license or is public domain?

• What specifically do you mean by a "convex" polygon on the sphere? (The concept appears problematic to me.) When you mean "find intersection," what form should the input have and what form should the output have? And when you say "no approximation," are you stipulating that you need very high accuracy in representing the edges? If that's the case, isn't there potentially a problem in using a spherical model instead of an ellipsoidal model of the earth's surface? – whuber Feb 24 '13 at 19:47 