Plane Below
Function Description: This tool allows the user to draw a plane, and select the point cloud below the plane.
Steps
1.Click Plane Below 
button, the selection mode is on and the function is activated
2.Identify the point clouds in the selected area for highlighting (red) display, as shown in the figure.
candidate region
Result map
3.After the plane is drawn, when there is no point cloud under the plane, there will be a pop-up prompt.
4.After the first selection is over, the next selection can be made on the basis of the first selection.
5.Each time the selection area is selected according to the reverse selection state, the corresponding plus selection area or minus selection area will be selected.
Note: This function is only for point cloud data.