The main outputs generated by SNAP are a listing file, which describes the adjustment, and a binary file, which is used by the SNAPPLOT program. If SNAP encounters errors it will also create an error file. Optionally SNAP can also generate comma or tab separated files of information about stations and observations in the adjustment for analysis by other programs.
If your command file is called MYJOB.CMD, then the listing file will be MYJOB.LST and the binary file will be MYJOB.BIN. The error file, if it is created, will be MYJOB.ERR.
If an error file is generated you should resolve the problems it identifies and run SNAP again.
The listing file provides a great deal of information about the adjustment. Your main purpose in viewing this file is to identify problems in the input data, such as gross observational errors, mistyped data, and misidentified stations. This is best done by reviewing the most significant residuals in the data which are listed at the end of the listing file, and by looking at the residuals of the individual observations.
If there are no obvious errors in the data then you should check the error ellipses and height errors of the calculated station coordinates to ensure that they meet the specifications of the job.
The SNAPPLOT program is useful for displaying the layout of the network and the geometry of the observations, the error ellipses and height errors of the stations, and the adjustments to station coordinates. For more information about SNAPPLOT see the SNAP utilities manual.
Common problems in SNAP adjustments
The following commands can be used in command and configuration files to control the outputs from SNAP