Toward an automated system for a correctly registered bathymetric chart

A scheme has been developed for automated bathymetric registration of multiple overlapping swaths of data collected by a ship equipped with a multibeam echo-sounder device. Because each swath of data overlaps with several others, registration is performed both at local and global levels. The primitives used for local matching are contours of constant depth which are extracted from the data and are represented as a modified chain code. The main heuristic guiding the search for matching contours of equal depth is their proximity to the middle of the apparent (unregistered) overlapping region. The degree to which two contours match is determined by the correlation of their respective chain codes and the geometrical proximity of their nodes. All best matches are considered tentative until their geometrical implications are evaluated and a consistent majority has emerged. To do global matching. a cost function is constructed and minimized