Seabed segmentation using a combination of high frequency sensors

Segmentation of the seabed in shallow water areas is of particular importance for several military and civilian applications. In this context, the SACLANT Undersea Research Centre is developing a procedure which consists of simultaneously operating three different acoustic sensors which are able to provide complementary information about an area of interest. A 300 kHz multibeam echosounder provides high resolution bathymetry and backscattering strength mapping. A sidescan sonar operating at the same frequency provides information about backscattering at low grazing as well as textural imaging. And thirdly, signals from a vertical echosounder are processed which enables a rough discrimination among various seabed types and complementary information on bathymetry. The combination of these three sensors with the use of unsupervised segmentation algorithms performed on sidescan images produce a high resolution mapping of the area. The testing of this procedure has been successfully performed on different well known sites using video imaging, sediment grab samples and photography. In this paper, the procedure is detailed and illustrated by one site survey. The limitation of such approach is stated and the way ahead is discussed.