SNAP (Survey Network Adjustment Package) is a suite of programs for adjusting the coordinates of stations in a survey network to best fit the observed data.
Generally these programs are accessed from the snap_manager program, though they can equally be run from a DOS command prompt.
The main programs in the suite are snap, which performs a least squares adjustment of coordinates to fit survey data and generates statistical information about the observations and the derived coordinates, and snapplot, which is a graphical tool for reviewing the results of an adjustment.
Generally in order to use snap you must first create data files detailing the observations used. You also need to create a station coordinate file which defines the stations in the adjustment. This should include the coordinates of the reference stations which will be held fixed in the adjustment, and trial coordinates for the other stations. The dat2site program may assist with generating trial coordinates. Finally you need to create a command file which defines the station coordinate file, data files, and adjustment options to be used. All these files can be generated in a text editor.
You can then open the command file in the snap_manager program in order to run and analyse the adjustment.
Several of the SNAP utility programs require the perl programming language to be installed on your computer. Perl for windows can be obtained from www.strawberryperl.com.