What is GNU Gama?

GNU (Free General Public License) Gama is a program for performing a least square adjustment of 1D, 2D and 3D survey observations. The project was initiated by Jan Pytel and Ales Cepek at the Department of Mapping and Cartography, Faculty of Civil Engineering, Czech Technical University in Prague in 1998. The program name Gama is derived as an acronym from Geodesy and Mapping. Gama has been presented at FIG conferences and received status of GNU license software in 2001. The accompanying user documentation is very well presented.

Gama adjusts observed coordinates, distances, angles/directions, height differences and 3D vectors in a local coordinate system. The observation data is formatted as an XML (Extensible Markup Language) input file. This makes it easy to read and edit the data. Gama is run simply as a command line program or via the companion GUI Rocinante (written by Jan Pytel) which is very well structured and easy to use.

Gama/Rocinante are excellent programs for land surveyors to integrate conventional angle/direction observations and derived autonomous GPS coordinates via a "classical free network adjustment". The less accurate autonomous GPS coordinates end up being adjusted to best fit and not distort the conventional survey network. See Sample 2D Horizontal Network.

As Gama was developed in the Czech Republic, angles/directions were formatted in the grad system. Ales recently made another change to the development version of Gama to provide an option of using degree input for angles and directions.

I am most grateful to Jan, Ales and the Gama project development team for making such a robust adjustment program accessible to the global survey community. Extraordinary efforts were made by this team to take that extra step in moving to GNU program status.

I encourage land surveyors to experiment with using Gama for integrating their horizontal and GPS observations as well as performing vertical adjustments.