RISK ASSESSMENT OF SEAFLOOR WASTE: ACOUSTICAL IMAGING OF BURIED WASTE
Abstract
This work describes some of the ongoing activities in the framework of the EU-sponsored project SITAR aimed at developing acoustic methods for imaging of waste barrels/containers of small dimension buried in unconsolidated sea sediments. In particular, the work relies on acoustic sub-bottom scattering measurement techniques, with adaptive geometrical configuration of the transmitting/receiving system. The approach ultimately leads to a full 3D measurement of the acoustic scattered field, including bottom and sub-bottom effects, plus the scattering due to buried objects in the scene. The 3D dense acoustic image is then processed in order to automatically extract relevant object(s) features, as size, 3D orientation, impedance contrast; this is obtained through a sequence of processing steps including filtering, enhancement, restoration and image segmentation. Preliminary results obtained with simulative data are presented: data are obtained by modeling the surfaces of both seabed and object(s) as a dense, random grid of discrete scatterers, following the Rayleigh reflection coefficient, and integrating the response of the scatterers. The effects due to absorption and refraction moving from water to sediments are also considered. Sediment volume inhomogeneities are modeled by a random distribution of small asymmetric scattering volumes, characterized by their 3D dimensions, density, and reflection coefficient. A volume growing segmentation approach has been applied, showing efficient segmentation capabilities, and robustness to uncertainty.
References
-
M. Zakharia and A. Belkacem , Synthetic aperture sonar for sub-bottom imaging, defocusing effects in the sediment , Proc. 10th Int. Conf. Sound Vibration ( 2003 ) . Google Scholar -
P. Skogqvist and I. Karasalo , A fast acoustic scattering method for buried objects , Proc. 10th Int. Conf. Sound Vibration ( 2003 ) . Google Scholar -
P. Dobbins , SITAR — Localisation and imaging of seafloor targets with multiple-aspect scattering , Proc. 10th Int. Conf. Sound Vibration ( 2003 ) . Google Scholar -
N. Jayasundere , Ph. Blondel and N. G. Pace , High-frequency bistatic scattering experiments in a laboratory tank , Proc. 10th Int. Conf. Sound Vibration ( 2003 ) . Google Scholar -
P. Jonsson , Underwater acoustic imaging for the assessment of seafloor waste: the SITAR project , Proc. 10th Int. Conf. Sound Vibration ( 2003 ) . Google Scholar - I. Karasalo, Simulated multi-aspect scattering from a buried object: description of model cases, FOI Memo, dnr. 02-1293 (2002) . Google Scholar
- Measurement Science and Technology 10, 1105 (1999). Crossref, Web of Science, Google Scholar
- IEEE Proc. 88, 1903 (2000). Crossref, Web of Science, Google Scholar
-
J. Rodriquez , R. E. Loke and J. M. H. du Buf , Fast Segmentation of 3D Data Using an Octree , Proc. 11th Portuguese Conf. Pattern Recogn. ( 2000 ) . Google Scholar - Computer Methods and Programs in Biomedicine 61, 23 (2000). Crossref, Web of Science, Google Scholar