Comparative Analysis of 3D Laser Scanning and Nap-of-the-Object Photogrammetry in Slope Protection Networks Measurement
The horizontal displacement monitoring network of dams is the plane benchmark for dam deformation monitoring.The reliability of the dam deformation monitoring results and the conclusion of the dam safety evaluation are subject to the precision of the monitoring network.In order to improve the data processing accuracy of the monitoring network,relying on the re-survey of the dam monitoring network of large-scale hydropower stations,the influence of relative humidity,slope distance flattening method,and earth curvature radius on the modifica-tion of side length is studied and analyzed.The results show that the maximum influence of relative humidity correction on side length can reach 2 ppm,the side length calculated by height difference in slope distance flattening is0.05~1.95 ppm higher than the side length calcu-lated by vertical angle,and the maximum influence of using the average curvature radius of the earth in the survey area instead of the earth curvature radius of the normal section line at the distance measurement side on the projected side length can reach 0.08 ppm;when process-ing the data of the high-precision monitoring network for dam horizontal displacement,relative humidity should be used to correct the meas-ured side length,and the slope distance flattening of height difference shall be adopted.The average curvature radius of the earth in the sur-vey area can be used instead of the earth curvature radius of the normal section line at the distance measurement side.The study results can provide reference for similar projects.
Horizontal DisplacementMonitoring NetworkRelative humidity correctionRefraction CoefficientEarth average Curvature Radius