Development of a Digital Photogrammetric System for Precise Deformation Measurement

点击翻译按钮获取中文摘要

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.