星载光子点云支持下的卫星影像区域网平差

Block Adjustment of Satellite Images Supported by Spaceborne Photon Point Cloud

以ICESat-2为代表的光子计数激光雷达对地观测手段具有地面足印小、采样频率高、波束数量多等特点,获取点云的平面精度和飞行方向数据密集程度得到很大提升,可作为一种新型三维控制条件以提高卫星影像定位精度。为解决光子点云没有同步影像记录平面位置的应用难题,提出一种星载光子计数激光点云支持下的卫星影像定位精度提升方法。首先采用三维地形剖面匹配方法实现对光子点云数据与卫星立体影像自动生成的数字表面模型(DSM)的精确配准;然后依据坡度变化从光子剖面点云中提取地形特征点,联合DSM多种地形特征生成共同地形特征控制点;最后将该地形特征控制点作为平高控制条件引入带附件参数的卫星影像区域网空中三角测量过程,以进一步提升定位精度。利用陕西省两个地区的ZY-3影像和ATLAS ATL03级数据进行实验,结果表明与完全无控定位方法和SRTM数据辅助定位方法相比,所提方法能够显著提高ZY-3影像平面和高程定位精度,提升幅度相对于SRTM数据分别可以达60%和34%左右,验证了所提方法的有效性和可行性。

The photon counting lidar earth observation means denoted by ICESat2 have the features of small ground footprints,high repetition frequency,and multibeams.The plane accuracy and flight direction data density of acquired point cloud have been greatly improved.As a result,it can be applied as a novel threedimensional control condition to enhance the precision of satellite image location.To address the application problem of photon point clouds without synchronous image recording plane position,the research suggests a technique to enhance the positional accuracy of satellite images supported by spaceborne photon counting laser point clouds.First,the threedimensional terrain profile matching approach is used to achieve precise registration between photon point cloud data and digital surface model(DSM)for the automatic generation of satellite stereo images.Then,terrain feature points are retrieved from the photon profile point cloud based on slope change,and the common terrain feature control points are produced by combining several terrain features of DSM.Finally,the terrain feature points as planimetric and elevation control conditions are added into the satellite image block adjustment with additional parameters to further improve positioning accuracy.Experimental results on the ZY3 satellite images and ATLAS ATL03 data in Shaanxi Province demonstrate that the proposed method can efficiently improve the accuracy of the ZY3 image plane and elevation positioning compared to completely uncontrolled positioning method and shuttle radar topography mission(SRTM)dataassisted positioning method.The proposed method’s efficacy and viability are confirmed by the fact that the increasing rates of plane accuracy and elevation positioning accuracy over SRTM data can reach 60%and 34%,respectively.