geodesic, gravity and geomagnetic calculations library
GeographicLib is a small C++ library for: * geodesic and rhumb line calculations; * conversions between geographic, UTM, UPS, MGRS, geocentric, and local cartesian coordinates; * gravity (e.g., EGM2008) and geomagnetic field (e.g., WMM2020) calculations; * computations on a triaxial ellipsoid.
Homepage: https://geographiclib.sourceforge.io/