基于已知定向参数影像的光束法区域网平差

从自检校光束法区域网平差模型出发,建立了利用同一地区已知定向参数的影像解求新获取影像外方位元素并进行目标定位的数学模型。以此为基础,对来自某地区相隔两年的三期不同摄影比例尺航空影像两两组合地进行联合光束法区域网平差。结果表明,当两期影像比例尺相近时,所解求的新影像外方位元素和加密点坐标精度基本达到常规光束法区域网平差的精度;当两期影像比例尺不同时,利用已知定向参数的大比例尺影像解求出的小比例尺影像的外方位元素和加密点坐标可满足现行规范精度要求,利用已知定向参数的小比例尺影像去解求大比例尺影像的外方位元素和加密点坐标精度明显下降且不可用。本文的研究证实,就同一地区的多时相航摄影像而言,利用已知定向参数的影像进行新影像的定向方法是可行的。

Bundle Block Adjustment Based on Imageries Given Orientation Parameters

According to self-calibrating bundle block adjustment, a mathematical model is set up at first, which solutes elements of exterior orientation of the new imageries by using imageries given orientation parameters in the same area. Then three sets of aerial imageries at different scales are taken respectively from the same area in 2002 and 2004. Finally the elements of exterior orientation of these new imageries and the 3D coordinates of photogrammetric points are calculated by combined bundle block adjustment with the derived mathematical model. The empirical results show that the elements of exterior orientation and the 3D coordinates of photogrammetric points are identical between the mentioned adjustment and the conventional bundle block adjustment for the two periods of imageries at the same scale. If the scales of the fixed imageries are bigger than the scales of new imageries, the solutions of the mentioned adjustment are better than that of the conventional bundle block adjustment. However, when the scales of the fixed imageries are smaller than the scales of new imageries, the adjustment accuracy has an apparent decrease and do not meet the specification of topographic mapping. The experiment has verified that determination of the orientation parameters of the new imageries by using the fixed imageries is correct in theory and is feasible in practice, and that the accuracy of the coordinates, which is gained purely by combined adjustment with two period of imageries, satisfies the requirement of the specification of topographic mapping. That is to say, aerial photogrammetry truly without any ground control point can be realized.