Bundle Block Adjustment with Optical and SAR Images

The combined bundle block adjustment model with optical and SAR images has been constructed in this paper, and its some key problems have been studied, such as construc- tion of observation equation, computation of weight matrix and the frame of computation pro- cess. Two experiments with the combination of difierent images (panchromatic SPOT-5 HRV, panchromatic SPOT-4 HRV, ERS-2 and RADARSAT-1) and difierent distributions of ground control points have been carried out. Preliminary experiment results with variant block adjust- ment schemes have proved the combined block adjustment model was feasible and correct. At last, the characteristics and application of the combined block adjustment have been summarized. Block adjustment is one of key techniques in photogrammetry, it is a procedure achieving orientation parameters of images and coordinates of pass points in a large area e-ciently and simultaneously (7). Up to now, what people focused on about block adjustment has not changed, it has been always the images photographed by one sensor at variant time and position. Since difierent photogrammetry and remote sensing sensors have been produced, the techniques processing difierent images achieved by difierent sensors have been proposed. Most works have been concentrated in radiative and physical processing, but a few people noticed multi-sensor images could be used to realize combined position. Young-Ran Lee (10) has carried on experiments about combined block adjustment based on improved collinearity condition equations (CCE) with multi-satellite remote sensing images includ- ing Landsat-7, KOMPSAT-1, SPOT-1, IKONOS. And in planimetry accuracy of 2.76m and in altimetry accuracy of 3.1m have been obtained. Thierry Toutin (5) has studied to evaluate the spatiotriangulation applied to multi-sensor satellite images. The spatiotriangulation was applied to 49 images in six blocks (Landsat-7 ETM+, panchromatic SPOT-4 HRV, multiband ASTER, multimode radar RADARSAT-1, and ERS-1) acquired from difierent viewing/look angles. The most important results Toutin obtained were related to simultaneous bundle adjustments of the largest \master" Landsat-7 block using 25 ground control points (GCPs) in the two outer strips and the smallest \slave" block(s) using no GCP but only elevation tie points (ETPs). The errors, verifled by a large number of independent check points (ICPs) in the \slave" blocks, were between 15{35m (1.5{2 resolutions). And the internal accuracy of the blocks was better (around one res- olution). In 2006 Thierry Toutin (6) has evaluated the spatiotriangulation applied to multi-sensor high resolution (HR) satellite images (SPOT-5 HRS, SPOT-5 HRG, IKONOS, Quick Bird). The errors obtained were 2.54m in planimetry and 2.1m in altimetry. The research study above mentioned demonstrated the possibility to use the large block with a reduced number of GCPs to simultaneously adjust single image(s)/strip(s) or smallest block(s) with only tie points (TPs), and with no degradation in the accuracy. In this paper, the combined bundle block adjustment model with optical and SAR remote sensing images has been constructed, and its some key problems have been studied. First the imaging models for linear array push-broom imagery and SAR imagery are introduced in Section 2. Then the mathematical model of combined bundle block adjustment is constructed in Section 3. Section 4 shows experimental results with a large block and Section 5 shows conclusions.