The Forward Search Method Applied to Geodetic Transformations

Abstract

In geodesy, one of the most frequent problems to solve is the coordinate transformation. This means that it is necessary to estimate the coefficients of the equations that transform the planimetric coordinates, defined in a reference system, to the corresponding ones in a second reference system. This operation, performed in a 2D-space is called planar transformation. The main problem is that if outliers are included in the data, adopting non-robust methods of adjustment to calculate the coefficients cause an arbitrary large change in the estimate. Traditional methods require a closer analysis, by the operator, of the computation progress and of the statistic indicator provided in order to identify possible outliers.

In this paper the application of the Forward Search in geodesy is discussed and the results are compared with those computed with traditional adjustment methods.