提出了一种大范围倾斜多视影像自动连接点提取和光束法区域网平差算法。首先利用POS数据对倾斜影像进行矫正并预测候选像对,使用SIFT特征进行影像匹配;然后利用并查集数据结构实现多视影像间连接点对应关系的快速确定;最后将POS数据和控制点数据作为带权观测值进行平差解算。选取3种典型的倾斜相机系统(组装轻量级倾斜相机、国产SWDC-5相机、微软UltraCam相机)进行了试验,结果表明,本文算法能够适应国内外流行的倾斜摄影系统,且一次性可处理的影像数目超过2000张;在相同条件下倾斜影像光束法区域网平差的整体精度优于传统垂直摄影情形,实际精度可以达到水平方向0.75 GSD,高程方向2.0 GSD。
A new tie-points extraction and bundle block adjustment method for large-scale multi-view oblique images is presented. Firstly, exterior orientation data gained by POS are used to rectify oblique images and predict image correspondences, which can be matched using SIFT algorithm. Secondly, an unordered feature tracking method relies on union-find algorithm are adapted to detect the multi-view correspondences. After tie-points extracted, bundle adjustment are done with POS and control points data treated as weighted measurement. In the experiment part, three kinds of oblique images, taken by assembled lightweight oblique system, UltraCam and SWDC-5, are used to test the algorithm above. The results show that our method can adapt the popular oblique systems at home and abroad, which can process over 2000 images at a time. And the precision of oblique triangulation is better than the traditional vertical triangulation, with an accuracy of 0.75 GSD in horizontal direction, 2.0 GSD in elevation direction.
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