Two Methods of Bathymetry Sidescan Sonar Data Comparison for Improved Determination of Sonar Towfish Position
Defence R and D Canada - Atlantic Dartmouth, Nova Scotia Canada
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Two methods are presented that use existing local bathymetric data to determine the position of the sidescan sonar towfish during surveys. In the absence of direct measurements of towfish position as survey work is underway, later determination of this position by other means is necessary to obtain accurately geo-referenced seabed imagery from the sonar data.The methods investigated rely on either large objects in the sonar field of view or the profile of the total water depth along the towfish survey track. Results of the analysis are compared with independent estimates derived from ship geometry and logbook cable length entries and from short-baseline acoustic tracking system measurements of the range to the towfish. In the several examples shown, both methods found layback solutions within a few metres of the independent estimates.