Development of a Digital Photogrammetric System for Precise Deformation Measurement

该项目（2001-2003年）的目标是开发一个近距离数字摄影测量系统，用于隧道和边坡的精确变形监测，以及桥砌块等大型结构的测量。主要研究课题及成果如下：为实现低分辨率数码相机视觉测量的实际测量精度，考虑了回溯目标的设计、拍摄技术和图像坐标的高速测量，最终稳定获得了400微米10米的三维精度。为了在一小时内处理大量图像（如30张或更多）以测量多个目标点（如100个或更多）的目标坐标，发展了包括目标图像自动标记和高速调整计算技术在内的图像处理技术。为了获得实际的测量精度、灵敏度和可靠性，考虑了网络设计问题。这个。彻底解决了零阶设计（参考系统的优化）问题。在视觉测量中，一阶设计（相机配置的优化）和二阶设计（观测权重的优化）是不可分割的。其中较好的部分是实验处理的，部分是理论处理的。通过多次实验，对实际应用中的测量方法和因素进行了测试和改进。它们是开挖中的隧道剖面测量、桥梁砌块的工业检测、混凝土梁的应力-应变试验和边坡的变形检测。为了监测远距离斜坡或岩石的变形，采用正交投影的特性代替了传统的中心投影。进行了研究。用虚拟的方式拍摄图像的定向方法。研究了无限长焦距相机及其标定方法，并证明了三幅图像可以重建出相似的空间。

The object of the project (2001-2003) is to develop a close-range digital photogrammetric system for precise deformation monitoring of tunnets and slopes, and measurement of large structures like bridge blocks. The followings are major research subjects and results.1.To attain practical measurement precision by vision metrology with a low resolution digital camera, design of retro-targets, photographing techniques and high speed measurement of image coordinates are considered and eventually 3-D precision of 400micro-meters for 10 m is stably obtained.2.To process a large volume of images (e.g. 30 sheets or more) to measure object coordinates of many (e.g. 100 or more) target points within an hour, image processing techniques including automatic labeling of target images, and a calculation technique for high speed adjustment are developed.3.To obtain practical precision, sensitivity and reliability of measurement, network design problems are considered. The. zero-order design (optimization of the reference system) is completely resolved. The first-order design (optimization of camera configuration) and the second-order design (optimization of observation weighting) cannot be separated in vision metrology. The better part of them is treated experimentally and partially theoretically.4.Through many experiments the measurement methods and factors in practical use are tested and improved. They are tunnel profile measurement in excavation, industrial inspection of a bridge block, stress-strain test of a concrete beam and deformation detection for a slope.5.To monitor deformations of long distant slopes or rocks, the properties of ortho-projection instead of conventional central projection. are studied. The orientation method of images taken with a fictitious. camera with an infinitely long focal length and the camera calibration methods are developed and it is shown that the similar space can be reconstructed from three images.