Preprocessing of Level Net (PLN)

This module produces data for level traverse misclosures and approximate elevation values. It is optional and does not need to be performed prior to a 1D net adjustment, due to its system of equations being completely linear. As such, this module's main purpose is calculating misclosures and checking against their maximum values. That functionality is also what the options prior to running this module define.

The traverse's misclosure is found using:

In a closed traverse, which begins from and ends in the same point, this expression simplifies to:

The maximum misclosure coefficient defines how standard deviations are multiplied to yield the final maximum misclosure threshold. Geolyth provides two options:

• -stat per

• Confidence interval coefficient per traverse

Where is the confidence interval defined prior to running the module, is the number of times an elevation difference was measured and returns the std. dev. coefficient given percentage .

Important! For elevation differences measured 1 or 2 times, cannot be determined, as it would only have 1 degree of freedom. The way Geolyth currently handles these cases is that it clamps the degrees of freedom value up to 2, which is clearly incorrect. In the future, unless a better mathematical model can be implemented, the first misclosure coefficient option will be forcibly disabled for traverses that contain a measurement with insufficient degrees of freedom.

In the future, a third maximum misclosure solution could be implemented, which uses traditional horizontal distance checks. Something like:

where k is some constant defined in the module's options (may be 10, 15, 20, 30, etc.)