Estimation and correction of geometric distortions in side-scan sonar images

This thesis introduces a new procedure for the enhancement of acoustic images of the bottom of the sea produced by side-scan sonars. Specifically, it addresses the problem of estimating and correcting geometric distortions frequently observed in such images as a consequence of motion instabilities of the sonar array. This procedure estimates the geometric distortions from the image itself, without requiring any navigational or attitude measurements. A mathematical model for the distortions is derived from the geometry of the problem, and is applied to estimates of the local degree of geometric distortion obtained by cross-correlating segments of adjacent lines of the image. The model parameters are then recursively estimated through deterministic least-squares estimation. An alternative approach based on adaptive Kalman filtering is also proposed, providing a natural framework in which a priori information about the array dynamics may be easily incorporated. The estimates of the parameters of the distortion model are used to rectify the image, and may also be used for estimating the attitude parameters of the array. A simulation is employed to evaluate the effectiveness of this technique and examples of its application to high-resolution side-scan sonar images are provided.

Grantor dc:publisher

Massachusetts Institute of Technology and Woods Hole Oceanographic Institution

Year dc:date.issued

1990

Author dc:creator

• Cobra, Daniel Távora de Queiroz

• Underwater acoustics
• Asterias (Ship : 1980-2004) Cruise

Language dc:language.iso

en_US

DOI

10.1575/1912/5426

OAI identifier oai:identifier

oai:darchive.mblwhoilibrary.org:1912/5426