近景摄影测量在边坡变形监测中的应用

某测量目标为一保证通电线路安全的护坡,高约10m,占地400多m2,其线杆立于护坡顶端中间,周边固定四个加强铁丝。护坡自修建以来,因周边土方作业及积水等因素,发生多次倒塌,为此采用近景摄影测量法进行变形监测以保证护坡维修重建的质量。根据测区实际概况,按照非同一平面及非同一线原则,布设控制点20个,控制点的坐标采用无棱镜观测方式,并选取广场瓷砖作为控制点的材质。通过对测量结果进行精度比较,认为该次测量景深方向X的精度相对较低,Y和Z方向的精度相对较好;基高比对精度有较大的影响;随着基高比的减小,精度有所提高,但如果继续减小基高比,精度反而会下降,因此选取适当的基高比是提高精度的关键;未经检校的非测量数码相机,存在较大的系统误差和构象畸变差,将会对测量精度产生较大影响。

Application of Close-range Photogrammetry in Slope Deformation Monitoring

A surveying object is a security slope for power line with land occupation more than 400m2 and about 10m high. The pole is on the slope top center with four wire guys. Since the slope was constructed, because of peripheral earthwork operations, waterlogging and other factors, toppled down several times. Therefore, close-range photogrammetry was used to carry out deformation monitoring to ensure quality of slope maintenance and reintegration. Based on surveying area practical situation, in terms of non- identical plane and non-identical line principle, 20 control points lay out, prismatic-free measuring was used in control point coordinate computing and paving tiles were used in control point material. Through accuracy comparison of measured results, considered that the accuracy of depth direction X is relatively low in this surveying, while Y and Z relatively better. The base-height ratio has major impact on accuracy, along with decreasing of the ratio, accuracy will be improved to some extent, but if the decreasing is continuing, accuracy will lower down on contrary, so suitable ratio is the key to improve surveying accuracy. Non-measuring digital cameras without calibration may have biggish systematic errors and image formation distortion errors and bring on larger impacts on surveying accuracy.