Side scan versus Multibeam Echosounder object detection: A comparative analysis

The undisputed remote sensing tool for detailed sea floor object detection is the side scan sonar. From pipelines, to downed aircraft, to mines, a sid e scan sonar's unique characteristics effectively ensonify and subsequently display these objects. For bathymetry, the Multibeam Echosounder (MBES) ha s quickly proven its superior capabilities. An MBES's unique characteristic s allow it to provide 100 per cent ensonification of the sea floor while me eting or even exceeding IHO specifications. During the 1997 Coastal Multibe am Sonar Training Course in Victoria, BC, inert mines were laid at differen t depths and then ensonified by a side scan sonar and an MBES. The aim of t his exercise was to compare the detection characteristics of the two sonars using one of the inert mines. This paper is a discussion of that compariso n and the lessons learned. Comparative imagery is used to illustrate the su ccess of each sonar in illuminating the mines to the operator. Unaided visu al detection is not always the most efficient method for finding objects in large quantities of MBES data; therefore, subtractive temporal analysis wa s implemented in order to enhance the MBES object detection process. As wel l, a simple automated detection algorithm was used successfully on the temp orally differenced images. The background, implementation and results of th e MBES subtractive analysis performed in the area of the inert mine will be compared to the detection achieved using the side scan sonar. Finally, con clusions will be drawn as to the efficacy of the MBES as an object detectio n sonar.