The button on top left create creates an empty corridor. To create the definition of a corridor, all the tools are on the right side of the interface. The corridor is set from a center line that can either be chosen "From alignment", "From picked line" or a list of point points picked on the point cloud. An offset from the centerline is specified on each side and the "Max. seg. length" specified specifies the length of segments in arcs and spirals when created from an alignment.
When the definition as has been created, a list of point points will be accessible beside the name of the corridor. This list represent represents the centerline. Points in it can then be removed, inserted, repicked or reorderreorganized. When a point is selected, a red dot will appear in the main point cloud to show its position.