Abstract: It is difficult to obtain high-precision ground point cloud data for vegetation covered slopes, which leads that it's difficult to accurately monitor the surface deformation of slopes. In this paper, a method is proposed to extract the deformation of slope by using the point cloud data on the sensor surface distributed on the slope body. The shape of GNSS antenna radome established on the slope is a spherical equipment with gradually changing radius. The circle center coordinates and radius are fitted by the point cloud slice, and the accuracy of the point cloud is evaluated by the fitting residual and the posterior mean square error, the quality control is realized. Through the comparison of radius in two phases, the matching of points with the same name is realized, and the purpose of point monitoring is achieved according to the coordinates of the circle center in two phases. Surface monitoring can be realized according to the steps on the slope and the peripheral equipment of the rain gauge. The measured data shows that the results of 3D laser scanning is consistent with the ones of GNSS monitoring, and the method can extract millimeter level deformation.

Key words: 3D laser scanner, slope, monitoring, point cloud slice, radome