Statistical autofocus of synthetic aperture sonar images using image contrast optimisation

Fortune, Steven; Gough, P.T.; Hayes, Michael

doi:10.1109/igarss.2001.976894

Cited by 12 publications

(8 citation statements)

References 9 publications

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“…The resulting image can be enhanced through an auto-focus algorithm that is based on a global contrast optimization technique (Fortune et al, 2001) …”

Section: Image Enhancingmentioning

confidence: 99%

Shallow Water Surveying Using Experimental Interferometric Synthetic Aperture Sonar

Silva¹,

Cunha²,

Matos³

et al. 2009

mar technol soc j

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A B S T R A C TThis paper describes an interferometric synthetic aperture sonar system based on an unmanned surface vehicle customized for shallow water environments. Synthetic aperture sonar enables imagery of high resolution that is independent of range by using the displacement of the sonar platform to create a large virtual array. If two geometrically displaced images are obtained, the construction of threedimensional topographic maps is possible through the use of interferometric techniques. The use of an unmanned surface vehicle presents several advantages that alleviate some problems related to the formation of synthetic aperture images, which are mainly related to the fact that a precise navigation system can be used for the boat control and sonar imagery motion compensation. Also, a small unmanned surface vehicle is advantageous in terms of cost of operation, maintenance and ease of deployment. Mapping of shallow water areas is an important task for many commercial and scientific applications like river navigability, infrastructure maintenance and natural resource monitoring. These tasks can be done efficiently with this system. Sample data obtained during test trials illustrate how synthetic aperture can be used to generate underwater imagery and bathymetric data. A B S T R A C TThis paper describes an interferometric synthetic aperture sonar system based on an unmanned surface vehicle customized for shallow water environments. Synthetic aperture sonar enables imagery of high resolution that is independent of range by using the displacement of the sonar platform to create a large virtual array. If two geometrically displaced images are obtained, the construction of threedimensional topographic maps is possible through the use of interferometric techniques. The use of an unmanned surface vehicle presents several advantages that alleviate some problems related to the formation of synthetic aperture images, which are mainly related to the fact that a precise navigation system can be used for the boat control and sonar imagery motion compensation. Also, a small unmanned surface vehicle is advantageous in terms of cost of operation, maintenance and ease of deployment. Mapping of shallow water areas is an important task for many commercial and scientific applications like river navigability, infrastructure maintenance and natural resource monitoring. These tasks can be done efficiently with this system. Sample data obtained during test trials illustrate how synthetic aperture can be used to generate underwater imagery and bathymetric data.

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“…The resulting image can be enhanced through an auto-focus algorithm that is based on a global contrast optimization technique (Fortune et al, 2001) …”

Section: Image Enhancingmentioning

confidence: 99%

Shallow Water Surveying Using Experimental Interferometric Synthetic Aperture Sonar

Silva¹,

Cunha²,

Matos³

et al. 2009

mar technol soc j

View full text Add to dashboard Cite

show abstract

“…If the expected errors are small they can be modelled as phase errors for each along-track position. If the sonar platform dynamic model is known, the number of search variables can be greatly reduced by parameterizing this model ( [Fortune, S. A. et al (2001)]). These parameters are weighted together with the image metric and serve as a cost function for the optimization algorithm to search the solution space (Fig.…”

Section: Auto-focusmentioning

confidence: 99%

Synthetic Aperture Techniques for Sonar Systems

Silva¹,

Cunha²,

Matos³

et al. 2009

Advances in Sonar Technology

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“…Metric-based autofocus schemes usually follow a common pattern [3]. First, a model of the global phase error is specified.…”

Section: Introductionmentioning

confidence: 99%

Deep Autofocus for Synthetic Aperture Sonar

Gerg¹,

Monga²

2020

Preprint

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Synthetic aperture sonar (SAS) requires precise positional and environmental information to produce well-focused output during the image reconstruction step. However, errors in these measurements are commonly present resulting in defocused imagery. To overcome these issues, an autofocus algorithm is employed as a post-processing step after image reconstruction for the purpose of improving image quality using the image content itself. These algorithms are usually iterative and metric-based in that they seek to optimize an image sharpness metric. In this letter, we demonstrate the potential of machine learning, specifically deep learning, to address the autofocus problem. We formulate the problem as a self-supervised, phase error estimation task using a deep network we call Deep Autofocus. Our formulation has the advantages of being non-iterative (and thus fast) and not requiring ground truth focused-defocused images pairs as often required by other deblurring deep learning methods. We compare our technique against a set of common sharpness metrics optimized using gradient descent over a realworld dataset. Our results demonstrate Deep Autofocus can produce imagery that is perceptually as good as benchmark iterative techniques but at a substantially lower computational cost. We conclude that our proposed Deep Autofocus can provide a more favorable cost-quality trade-off than state-of-the-art alternatives with significant potential of future research.

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Statistical autofocus of synthetic aperture sonar images using image contrast optimisation

Cited by 12 publications

References 9 publications

Shallow Water Surveying Using Experimental Interferometric Synthetic Aperture Sonar

Shallow Water Surveying Using Experimental Interferometric Synthetic Aperture Sonar

Synthetic Aperture Techniques for Sonar Systems

Deep Autofocus for Synthetic Aperture Sonar

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