The ambiguity of the results of the strict adjustment of horizontal geodetic networks

Abstract

The algorithm of the strict adjustment of horizontal geodetic networks using least square adjustment method is well known and widely described in the literature. Referring to the Regulation of the minister of administration and digitization of 14 February 2012 on geodetic, gravimetric and magnetic control networks, which is in force in Poland, the authors draw attention to the important provision contained in this Ordinance: Observa-tions should be adjusted using a rigorous adjustment, based on least square adjustment method, assuming zero variance for references points. Assumption of zero standard deviations for references points causes that, despite net-work adjustment process is rigorous, results obtained, both adjusted coordinates and the assessment of the accuracy of the coordinates, depend on the method of establishing the network, the number of points and the actual accuracy of references points. On the ex-ample of the small test network, there was demonstrated how important differences can be. The only solution to the problem of the ambiguity of the results of strict network ad-justment is taking into account the accuracy of references points. It should be noted that the coordinates of references points can be a result of adjustment of various networks in various time periods, so they can be determined with various precision. Taking into ac-count this fact can only be done by determining reliable relationship between weights of observations and coordinates of references points.