Image processing techniques for sector scan sonar

[摘要] ENGLISH ABSTRACT: Sonars are used extensively for underwater sensing and recent advancesin forward-looking imaging sonar have made this type of sonar an appropriatechoice for use on Autonomous Underwater Vehicles. The imagesreceived from these sonar do however, tend to be noisy and when usedin shallow water contain strong bottom reflections that obscure returnsfrom actual targets.The focus of this work was the investigation and development of post-processingtechniques to enable the successful use of the sonar images for automated navigation.The use of standard image processing techniques for noise reductionand background estimation, were evaluated on sonar images with varyingamounts of noise, as well as on a set of images taken from an AUV ina harbour.The use of multiple background removal and noise reduction techniqueson a single image was also investigated. To this end a performancemeasure was developed, based on the dynamic range found inthe image and the uniformity of returned targets. This provided a meansto quantitatively compare sets of post-processing techniques and identifythe 'optimal processing.The resultant images showed great improvement in the visibility oftarget areas and the proposed techniques can significantly improve thechances of correct target extraction.

[发布机构] Stellenbosch University