Abstract：For problem of the laser beam not being perpendicular to the ground, ground point spacing calculation method was deduced. With the field observation, the accuracy and feasibility of the calculation results were tested and the best scanner scanning radius was obtained. The result shows that by comparing the elevation of point clouds model and the 16 homonymy point using level monitoring measurements,the difference of corresponding point elevation and level measurement point is not obvious. It is stated that the 3D laser scanning technology has high accurate and can be used for deformation monitoring of the subsidence zone.
