重力地形改正是区域重力测量工作中的一个关键步骤,按照测区范围分为近区、中区和远区地形改正。中区和远区的地形改正基于已有的中小比例尺地形数据库比较容易实现,但近区地形改正对于地形产品精度的要求较高而相应的大比例尺地形数据缺乏,实际作业中仍然需要外业大量的人工采点和内业处理生成近区地形,严重制约了重力测量工作的精度和效率。因此,如何快速价廉地重建重力测站附近高精度的3维地形,成为目前高精度区域重力测量工作中亟待解决的具有挑战性的问题。本文提出了一种基于全景立体视觉和摄影测量技术的快速近区重力地形改正方法,设计和开发了相应的快速地形测图系统,能够自动生成近区高精度的数字地形模型并解算出相应的近区重力地形改正值,从而实现了近区地形改正的高精度和自动化。系统的设计思想是在满足精度要求的前提下集成价廉可靠的硬件单元并开发专门软件实现可应用推广的系统,而不是采用昂贵的高端硬件以达到最高的精度。全景立体测图系统的硬件单元包括两台工业相机与固定基线构成的立体相机、双自由度(水平±180。,竖直±36。)旋转云台和支撑采集设备的三脚架,并通过笔记本控制云台和立体相机采集测站周围的影像。这些硬件的选取与配置基于理论精度分析与设计优化,结果表明测站50m范围内的3维测量精度优于1m,满足近区地形改正的精度需求。为了实现理论上的测图精度,采用控制点均匀分布的3维控制场,对立体测图系统的几何参数进行了精确标定,其中包括相机的内参数、畸变系数、立体相机的相对位置姿态以及云台旋转轴和中心的偏移参数。基于标定后测图系统精准的几何参数,从360。全景立体影像建立无缝的立体模型,采用兴趣点提取、自相关和
Gravity terrain correction is a critical step in regional gravity survey. The main challenge for gravity terrain correction is how to rapidly and inexpensively reconstruct high-quality terrain near the gravity survey station. This paper proposes a fast nearregion terrain correction approach based on panoramic stereo vision and photogrammetry techniques. A fast and low-cost topographic mapping system is designed and developed for this purpose. To miniaturize the system and assure required mapping accuracy, we theoretically analyze and optimize the hardware design. The developed software system generates DEM automatically from panoramic stereo images and calculates the gravity correction value at each station. The system has been verified in several filed tests with various terrain circumstances. The test results demonstrate that the developed gravity terrain correction method significantly outperforms the traditional field surveying methods in efficiency and accuracy.