The Image Added button on top left create 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 a chosen "From alignment", a "From picked line" or a lit list of point picked on the point cloud. An offset from the centerline is specified on each side and the "Max. seg. length" specified the length of segments in arcs and spirals when created from an alignment.
When the definition as been created, a list of point will be accessible beside the name of the corridor. This list represent the centerline. Points in it can then be removed, inserted, repicked or reorder. WHen When a point is selected, a red dot will appear in the main point cloud to show its position.