GNU Gama is a project dedicated to adjustment of geodetic networks. It
is intended for use with traditional geodetic surveyings which are
still used and needed in special measurements (e.g., underground or
high precision engineering measurements) where the Global Positioning
System (GPS) cannot be used.

Adjustment in local Cartesian coordinate systems is fully supported by
a command-line program gama-local that adjusts geodetic (free)
networks of observed distances, directions, angles, height
differences, 3D vectors and observed coordinates (coordinates with
given variance-covariance matrix). Adjustment in global coordinate
systems is supported only partly as a gama-g3 program.

Homepage:
https://www.gnu.org/s/gama/
