一种更严密的双介质立体摄影测量折射改正算法

提出一种更严密的双介质立体摄影测量物方坐标折射改正算法。该算法用水下目标的空中同名直线光线公垂线段的中点作为摄影测量交会点的理论位置,解决了空中同名直线光线延长线不相交情况下摄影测量交会点不存在导致的点位关系不确定性问题,使摄影测量交会点到真实物点的坐标折射改正公式能够严格推导出来。分析了空中同名直线光线不相交情况对物方大地坐标折射改正的不利影响,研究了摄影测量交会点与水下真实物点的相互位置关系,推导了水下目标点的水深和大地坐标计算公式(即折射改正公式),通过WorldView-2立体影像浅海海底地形测量试验对算法的正确性和测量精度进行验证。研究表明,不论水下目标的空中同名直线光线延长线是否相交,该算法都是适用的,且能显著改善水下目标的高程测量精度。

More Rigorous Correction of Refraction Effects in Two-media Stereophoto-gr ammetry

A more rigorous algorithm is presented for correction of refraction effects in two-media stereo photogrammetry .The mid-point of the shortest line segment joining two aeri al corresponding rays of a point on an underwater object is used as a photogrammetric intersection point which doesn't exist when the two rays are non-intersecting .As a result ,the uncertainty of the intersection point is removed ,the positional relationship between the intersection point and the true object point becomes definite ,and the refraction correction formula from the intersection point to the true object point can be strictly derived.The bad effect on the refraction correction is firstly analyzed ,which caused by that the two rays are non-intersecting .Then the positional relationship between the intersection point and the true object point is studied.Afterthat,the formulas regarding water depth and geodetic coordinates of points on an underwater object are deduced , that is often known as correction of refraction effects .Finally ,the algorithm is tested by two experiments using the data of WorldView-2 .The results show that the algorithmis suitable for any case in which whether or not the two aerial corresponding rays of an underwater object point are intersecting , and it can significantly improve the measurement accuracy of underwater object's elevation .