Application Of Close - Range Photogrammetry In Slope Monitoring

In recent years, with the rapid development of the close-range photogrammetry technology,which is becoming a new and non-contact measurement method. Compared with traditional monitoring methods, the close-range photogrammetry technology has some advantages, such as it can get geometrical and physical information of the measured object instantly, and less outdoor work and so on. However, the cameras for special measurement are expensive and complicated to operate,which restricts the development and application of close-range photogrammetry technology. Ordinary digital camera applys on the slope monitoring,which is researched in this paper. Based on the actual engineering, with the developed monitoring systems, a small amount of points, as control points, was collected by GPS to solve coordinate of a large number of unknown points, which has a very good practical significance.The main contents and results are:(1) Calibration method based on vanishing point and Lensphoto system were used to calibration experiment camera, which obtained the camera’s internal parameters. Parametric analysis finded that the main point and the main distance of the digital camera are relatively stable, but the distortion parameters are discrete.(2) VS2008 was used to develope the close range photogrammetry system, choosing direct linear transformation as an analytical method, which solves the difficult issues of feature extraction used DLT algorithm and coordinate solver. A pit located in Qixia district was chosen as the experiment pit. Those coordinates of unknown points were solved by six known control points, the stability and accuracy of the developed system were verified compared with the coordinates measured through GPS.(3) Appling the monitoring system on foundation pit project in Gulou District, Nanjing, the monitoring operation as follows:site layout points, continuous shooting photographs, survey control point coordinates, feature point extraction, import data solver, and ultimately get slope displacement.(4) A new method is proposed to estimate the spatial coordinates of the unknown point in the slope by the control point out of the slope. This method can reduce the computation error effectively.(5) The coordinates were calculated through the method of image mosaic, which used pixel weighted fusion method and SIFT to extract feature vector. Analyze the method and draw some conclusions.