Browsing by Author "Williams, David P."
Now showing items 1-15 of 15
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Adaptive underwater sonar surveys in the presence of strong currents
Williams, David P.; Baralli, Francesco; Micheli, Michele; Vasoli, Simone (CMRE, 2017/11)We consider the task of conducting underwater surveys with a sonar-equipped autonomous underwater vehicle (AUV) in environments with strong currents. More specifically, this topic is addressed in the context of mine ... -
AUV-enabled adaptive underwater surveying for optimal data collection
Williams, David P. (NURC, 2012/04)A new adaptive strategy for performing data collection with a sonar-equipped autonomous underwater vehicle (AUV) is proposed. The approach is general in the sense that it is applicable to a wide range of underwater tasks ... -
Demystifying deep convolutional neural networks for sonar image classification
Williams, David P. (CMRE, 2019/06)Deep convolutional neural networks (CNNs) are developed to perform underwater target classification in synthetic aperture sonar (SAS) imagery. The deep networks are trained using a huge database of sonar data collected at ... -
Efficient dense sonar surveys with an autonomous underwater vehicle
Williams, David P.; Couillard, Michel (CMRE, 2014/01)An algorithm for the in situ adaptation of the survey route of an autonomous underwater vehicle (AUV) equipped with side-looking sonars was recently proposed. This algorithm immediately exploits the through-the-sensor data ... -
Exploiting phase information in synthetic aperture sonar images for target classification
Williams, David P. (CMRE, 2019/05)It is demonstrated that the phase information present in complex high-frequency synthetic aperture sonar (SAS) imagery can be exploited for successful object classification. That is, without using the amplitude content of ... -
Fast unsupervised seafloor characterization in sonar imagery using lacunarity
Williams, David P. (CMRE, 2019/06)A new unsupervised approach for characterizing seafloor in side-looking sonar imagery is proposed. The approach is based on lacunarity, which measures the pixel-intensity variation, of through-the-sensor data. No training ... -
The Mondrian detection algorithm for sonar imagery
Williams, David P. (CMRE, 2019/06)A new algorithm called the Mondrian detector has been developed for object detection in high-frequency synthetic aperture sonar (SAS) imagery. If a second (low) frequency-band image is available, the algorithm can seamlessly ... -
Multi-look processing of high-resolution SAS data for improved target detection performance
Williams, David P.; Hunter, Alan Joseph (CMRE, 2019/06)The rich content of synthetic aperture sonar (SAS) data is typically used to generate imagery with resolution as high as theoretically possible. But when the ultimate purpose of the imagery is for detecting objects with ... -
Multi-view SAS image classification using deep learning
Williams, David P.; Dugelay, Samantha (CMRE, 2017/11)A new approach is proposed for multi-view classification when sonar data is in the form of imagery and each object has been viewed an arbitrary number of times. An image-fusion technique is employed in conjunction with a ... -
The new muesli complexity metric for mine-hunting difficulty in sonar images
Williams, David P. (CMRE, 2019/05)A new image complexity metric has been developed that fuses the concept of lacunarity, a measure of pixel intensity variation, with the notion of spatial information, a quantity that captures edge energy. This new metric, ... -
On adaptive underwater object detection
Williams, David P. (NURC, 2012/04)A new algorithm for the detection of underwater objects in sonar imagery is proposed. One particularly novel component of the algorithm also detects the presence of, and estimates the orientation of, sand ripples. The ... -
On the effects of synthetic-aperture length on SAS seabed segmentation
Williams, David P.; Groen, Johannes (NURC, 2009/12)In this work, we quantify the relationship between synthetic-aperture length (or equivalently, along-track resolution) and seabed segmentation performance experimentally for real synthetic aperture sonar (SAS) imagery. The ... -
On the relationship between SAS image resolution and target-detection performance
Williams, David P.; Hunter, Alan Joseph (CMRE, 2019/06)The relationship between synthetic aperture sonar (SAS) image resolution and target-detection performance is quantified. It is first demonstrated how a lower-resolution SAS system can be simulated in a principled manner ... -
Passive acoustic surveillance of surface vessels using tridimensional array on an underwater glider
Tesei, Alessandra; Been, Robert; Cardeira, Bruno; Galletti, Domenico; Cecchi, Daniele; Garau, Bartolome; Maguer, Alain; Williams, David P. (CMRE, 2019/06)The NATO-STO Centre for Maritime Research and Experimentation (CMRE) has proposed to approach the problem of monitoring marine traffic in defined sea areas by using passive acoustics on a mobile underwater platform, in ... -
Underwater target classification in synthetic aperture sonar imagery using deep convolutional neural networks
Williams, David P. (CMRE, 2019/06)Deep convolutional neural networks are used to perform underwater target classification in synthetic aperture sonar (SAS) imagery. The deep networks are learned using a massive database of real, measured sonar data collected ...