This article analyzes the technology of creating and updating a digital topographic map using the method of mapping (generalization) on an updated map with a scale of 1 : 25;000 based on the source cartographic material. The main issue in the creation of digital maps is the study of map production accuracy and error analysis arising from the process of map production. When determining the quality of a digital map, the completeness and accuracy of object and terrain mapping are evaluated. The correctness of object identification, the logical consistency of the structure, the and representation of objects are assessed. The main and the most effective method, allowing to take into account displacement errors for the relief during image processing, is orthotransformation, but the fragment used to update the digital topographic map needs additional verification of its compliance with the scale requirements of the map. Instrumental survey will help to clearly identify areas of space image closer to nadir points and to reject poor quality material. The software used for building geodetic control network should provide stable results of accuracy regardless on the scale of mapping, the physical and geographical conditions of the work area or the conditions of aerial photography.
The paper presents empirical methodology of reducing various kinds of observations in geodetic network. A special case of reducing the observation concerns cartographic mapping. For numerical illustration and comparison of methods an application of the conformal Gauss-Krüger mapping was used. Empirical methods are an alternative to the classic differential and multi- stages methods. Numerical benefits concern in particular very long geodesics, created for example by GNSS vectors. In conventional methods the numerical errors of reduction values are significantly dependent on the length of the geodesic. The proposed empirical methods do not have this unfavorable characteristics. Reduction value is determined as a difference (or especially scaled difference) of the corresponding measures of geometric elements (distances, angles), wherein these measures are approximated independently in two spaces based on the known and corresponding approximate coordinates of the network points. Since in the iterative process of the network adjustment, coordinates of the points are systematically improved, approximated reductions also converge to certain optimal values.