Applied Study On Displacement Measurement With Ordinary Digital Camera In Geotechnical Engineering

In the traditional displacement measurement of geotechnical engineering, professional measurement camera has been the mainstream.But the complicated operation and the high cost has greatly limited the application in geotechnical engineering.In recent years,with the development of CCD technology,High resolution ordinary digital cameras have become more widespread.Because the image is clearer and can be directly processed by computer,it has many advantages in photogrammetry.But ordinary digital cameras are not measurement cameras,and it can not be applied to digital photogrammetry directly.Therefore,study on displacement measurement with ordinary digital camera in photogrammetry will be of great theoretical and practical significance.Displacement measurement method with ordinary digital camera to is based on the theory of Photogrammetry and supported by computer digital image processing. This thesis studies the theory of photogrammetry and digital image processing deeply on the background of displacement measurement in geotechnical engineering.The method provides a new way for the displacement measurement in geotechnical engineering.The results of the thesis are as follows:1.Thesis presents the basic theory of digital photogrammetry from geometry angle and studies fundamental methods,for example,spatial coordinate transformation, backward resection and forward resection.And this work provides theoretical foundation for displacement measurement with ordinary digital camera.2.Thesis studies the specialty of displacement measurement with ordinary digital camera and concludes that there are three problems need to solve,unknown interior element,lens distortion,reckoning initial exterior element.Thesis provides corresponding solution for these problems and designed algorithm which is proper for displacement measurement with ordinary digital camera.3.The process of getting feature point's image coordinate is very important in the displacement measurement with ordinary digital camera.Image segmentation is a good way to accomplish this task.Thesis studies image gray transformation,smooth, sharpening and segmentation algorithm deeply.According to the specialty of displacement measurement in geotechnical engineering,after minus the background, iterative threshold selection method and Otsu threshold selection method are adopted. And then the image process procedure is designed for the system.Executing results of the software developed based on this method show that the precise is very high.4.A displacement measurement software is developed obey the theory of software engineering.Related algorithms are encapsulated in the software.The software is tested preliminarily in the thesis,and the results show that the software run stably and result is high precise.The results of the thesis indicate that displacement measurement with ordinary digital camera is feasible.And compare to the traditional displacement measurement method in geotechnical engineering,this method is not only more convenient and more automatic,but also more chip.The application prospect is bright.