Spheres is a A Java package for doing spherical trigonometry without all the
messy (and cpu intensive) trigonometry. The spheres package includes classes
for points, spherical polygons, latitude/longitude bounding boxes, orbits, and
scenes. Spheres documentation includes a variety of algorithm descriptions for
performing areal comparisons on the ... sphere.
The spheres package itself performs areal comparisons on the sphere for
spherical polygons, lat/lon bounding boxes, orbits, and scenes. At the moment
the package is incomplete and not fully tested, except for the parts we're
actually using. The javadoc documentation is on-line to give you an idea of
what it does, or should do. The source code and the class files are also
available in separate jar files (right click and "save as"). Or, if you're
really keen, there's everything in one big jar file.