Sensitivity of Texture Parameters to Acoustic Incidence Angle in Multibeam Backscatter

Abstract

Texture analysis is one of the principal methods by which acoustic backscatter information is analyzed and classified. Recently, its application to the identification of subtle changes in acoustic images, such as the identification of marine life, has begun to increase. To utilize texture analysis for these purposes, the effect of survey geometry on texture parameters must be understood. A dense net of multibeam echo sounder data was recorded with a sixfold overlap to study the impact of the acoustic incidence angle on selected texture parameters derived from a Haralick gray-level co-occurrence matrix. The results show that a correlation of up to 0.29 exists between the beam angle and texture values in sedimentary facies. This correlation depends on the seafloor composition. The correlation is masked when seafloors of different compositions are considered, and it is reduced with decreasing image resolution. The observed effects are relevant when subtle seafloor changes are considered, and they may also be responsible for the comparably poor performance of texture analysis in several habitat mapping studies.