Aerotrianguliacija naudojant kinematinio GPS metodo rezultatus

Abstract

The Geodesy Institute of VGTU using aerotriangulation approach has created a photogrammetrie base of aerophotography at a scale of 1:6000 for making the basic digital map for GIS of Vilnius city(Fig 1) [1]. A new Norwegian aerotriangulation method has been applied with its main features: usage of perspective centre co-ordinates determined by aeroplane GPS, self-calibration of aerocamera’s inner orientation parameters and block adjustment of network applying collinearity condition of projective rays [3]. Norwegian AO “Fjellanger Widerøe” performed the aerotriangulation of first small block. Data of first table describe the size of block networks. The Geodesy Institute created methods, the program of calculation, - controlled ant adjusted point co-ordinates (200 points) in overlapped places of all three blocks. The aerophotography was taken in the spring of 1995 by the Norwegian AO “Fjellanger Widerøe” using modern instrument RMK TOP (ck =153.60 mm) an aeroplane with installed GPS. The transversal aerotriangulation strips at a scale of 1:8000 were made at the eastern and western edges of blocks. Before taking aerophotography 54 control points were signalled. Co-ordinates and elevations of these points were determined by GPS method. Point co-ordinates of aerotriangulation were measured in aeropositives by the analytic instrument Leica SD 2000 ( block 3) and precise stereocomparator Stecometer (block 2). Transversal parallaxes py at the model points were received from 5 to 10 µm. Connecting models into strip network and strips into block, differences of connected point co-ordinates vx, vy were reached to 15 µm, and vz - to 20 µm (in a wooden territory). Calculation and adjustment of aerotriangulation is performed in two stages: 1) creation of single photogrammetrie model (by programme ORPROG), connection models to strip network and recalculation of strip network to entire block network (Schut method[2]), transformation to geodetic system; 2) adjustment of block network by NLHBUNT program [4]. The aim of first stage is to define preliminary point co-ordinates. The model of mathematics block network adjustment has been based on collinearity equations (1). Equations of aeroplane GPS antenna co-ordinate corrections are involved into process of adjustment (2), too. The accuracy of aerotriangulation block network is described by these data: - mean square standard of weight unit (of point measurement) in the first block is 4.1 µm, in the second 5.8 µm and in the third block 8.3 µm (in a wooden territory); - empirical standards of point co-ordinates ; Sx, Sy and Sz, calculated in the process of network adjustment are shown in Table 2; - deviations from values determined by GPS method of control point photogrammetrie co-ordinates X,Y,Z - in the first and second blocks are reached to 6 cm; in the third block to 10 cm. New block aerotriangulation method based on GPS determined the projective centres co-ordinates of aerophoto is effective and accurate method of creation photogrammetrie reference. An accuracy of created aerotriangulation in Geodesy Institute satisfies technological and accuracy requirements for construction of basic digital map for Vilnius GIS using the stereophotogrammetric approach.