Explore Different Approaches of Processing Backscatter Angular Response Curves for Seabed Mapping  

Authors / CoAuthors

Huang, Z. | Siwabessy, J. | Brooke, B. | Anderson, T. | Nichol, S.

Abstract

The aim of the study was to explore different approaches of feature selection, extraction and reduction from backscatter angular response curves for a relatively complex seabed. The study area is located at Point Cloates along the coast of central Western Australia where water depths range from 6 to 200 m and is characterised by extensive sandy bedforms, flat sandy seabed and numerous reefs. A Simrad EM3002 300 kHz sonar system was used to collect multibeam data across an area of 281 km2 in 2008. A series of radiometric and geometric corrections were applied to the backscatter data. The angular response curves were derived separately for port and starboard by averaging 100 pings along the ship track. Seabed sediment texture was characterised from 90 samples that were analysed for grain size properties (gravel, sand, mud%) and classified into six sediment classes. Co-located towed-video transects from the survey were used to identify areas of rocky seabed. Four approaches of processing the angular response curves have been explored. The first approach used all effective beam angles (4o to 51o) with a manual feature selection method in the modelling process. The second approach used principal component analysis to condense the 48 variables into four (explained 99% data variance). The third approach extracted nine parameters from two domains of the angular response curves including slope, intercept, orthogonal distance and mean. The fourth approach derived continuum-removed angular response curves. Probability Neural Network was used as the classifier. The classification results show that the continuum removal approach performed the best with an overall accuracy of 73% when classifying the seven seabed classes (Figure 1).When merging the six sediment classes into four, which results in five seabed classes, the performance was improved for all approaches.

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nonGeographicDataset

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71581

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• External PublicationAbstract

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• marine

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• CERF

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

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2011-01-01T00:00:00

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