Mosaicing of 3D sonar data sets - techniques and applications

This paper presents a system for registration of 3D sonar data sets based on the Echoscope 1600 3D sonar. Although a 3D sonar image provides instantaneous volumetric data sets, many applications require the data sets to be mosaic´ed into larger data sets. The lack of navigation and motion sensors being able to produce mosaics with accuracies comparable to the 3D sonar resolution necessitates the use of registration techniques. Techniques for filtering of 3D sonar data, mesh generation, registration and geometric fusion applied to both on-line and offline mosaicing will be discussed. On-line mosaicing is done at a rate of 5 to 10 data sets per second, a rate that is acceptable in most practical situations. The techniques will find a number of applications, such as scanning harbors and seabed for potentially dangerous objects as well as seabed surveys. As the registration provides the sensor position relative to an object, object related positioning and navigation is also feasible, either as a stand alone underwater navigation system or as a system that improves current techniques like LBL, SBL and others.