Ortodroma

The shortest connection of two points on the surface of a sphere is called an orthodroma. An orthodroma on a sphere is a circle. It is formed as the intersection of the spherical surface and a plane defined by three points:

• The starting point of route P1
• End point of route P2
• Centre of sphere S

The sphere1.exe program determines not only the length of the orthodromo, but also the azimuths at the end and start points. The program also prints a table of intermediate points that lie on the orthodrome at any interval. For each intermediate point, the latitude, longitude, and longitude are specified. longitude, azimuth and distance from the origin. The program is controlled from the command line and is portable to most platforms.