1. A method of producing a three-dimensional (3D) model of an underground environment, comprising the steps of: a) acquiring 3D information of an underground environment from at least one range sensing device; b) producing a 3D model of the underground environment from the acquired 3D information suitable for visualization, analysis or post-processing; c) locating the range sensing device by back-sighting to at least two existing survey stations located in the underground environment using a second range sensing device in a fixed relationship to said first range sensing device; and d) based on the position information from step c, transforming the 3D model of the underground mine to a map of the underground environment in a coordinate frame of reference of the underground environment.