Blokinės aerotrianguliacijos efektyvumas sudarant geodezinę atramą

Abstract

A new aerotriangulation approach was used for creating photogrammetric reference by aerophotography at a scale of 1:6000 for compiling the basic digital map of Vilnius city. Aerotriangulation was applied where the main feature is usage of perspective centre co-ordinates determined by aeroplane GPS [1]. Self-calibration parameters of aerocamera interior orientation (1,2) were involved in block adjustment of network (NLHBUNT program [3]). The aerial block triangulation of Vilnius city (block 2) was investigated with regard to integration of kinematic GPS results into the aerial triangulation. The block adjustment simulation was made in the following way: variants of block adjustment were chosen with a most precise, traditional, minimum number of ground control points, traditional with minimum ground control points, and kinematic GPS data aerial triangulation. Theoretical (3) and practical (4) accuracy of aerial triangulation network was estimated according to data of simulated block aerotriangulation network’s in magnitude of 2-4 cm and confirmed by an experiment using a large, irregular GPS- photogrammetric block based on a large scale aerophotography. The results of simulation data show the possibility of aerial triangulation exceptionally with kinematic GPS data; estimated theoretical accuracy of block network does not correspond to the actual reality. Distribution of planimetric point position errors is circular (mx ≅ my,,). Errors of point elevations are significantly larger (Table 3). Practical accuracy always shows actual precision reality of aerial triangulation. The results of aerial triangulation need to be checked by geodetic control methods. As regards the tasks of engineering geodesy, relative accuracy of aerotriangulation was investigated. It shows that aerotriangulation with kinematic GPS data satisfies the requirements of geodetic engineering tasks. Reliability analysis includes internal and external reliabilities. For the reliability analysis the local redundancy numbers ri (6) need to be determined. The best values for the reliability measures (7, 8) were obtained from network adjustment variant 1, which imply the traditional aerotriangulation with kinematic support. Mathematical statistical estimation of aerotriangulation network adjustment results were carried out using software “Statgraf” (Tables 6, 7). Obtained data are nearly distributed according a normal distribution. Blunders in the results of aerotriangulation network adjustment are not discovered. The new block aerotriangulation method based on GPS determining the projective centre co-ordinates of aerophotos is an effective and accurate method for creating photogrammetric reference. Geodetic field works and expenses should be reduced using the new aerotriangulation method. The obtained accuracy of the created photogrammetric reference satisfies the technology and accuracy requirements for construction of thematic digital map for the city using the stereo- photogrammetric approach.