Imaging the topology of the seabed

This paper is concerned with the process of creating an image of the topology of the seabed. At present, many sonar systems exist which create images of representations of the seabed. They are representations since the signals are essentially formed in time and do not represent exactly the seabed. Furthermore, processing algorithms for object detection and texture segmentation assume that the seabed is flat. This more often than not is a gross simplification. To overcome this problem we present a method for measuring the topology (or bathymetry) and also present a model for its assessment and some real results. Sound is an excellent source for propagating through water and for creating images of the seabed. Normally the sound sources or sonar transducers are towed behind a vessel and they insonify areas of the seabed. In this paper relatively high resolution sonar is modelled and imaged. Typically, ranges of up to 200 metres are covered either side of the transducer (or fish as it is often called). To measure the topology, use is made of a set of transducers which capture the phase differences of the sound as it returns from the seabed. A model is developed to estimate the errors involved and some simulations and reconstructions given. Finally some real data is used to show the effects in practice