Browsing by Author "Hansen, Roy Edgar"
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3D Rendering of Shipwrecks from Synthetic Aperture Sonar
Lorentzen, Ole Jacob; Hansen, Roy Edgar; Sæbø, Torstein Olsmo; Synnes, Stig Asle Vaksvik; Geilhufe, Marc (2021-10-25)Synthetic aperture sonar (SAS) bathymetric mapping provides centimeter-scale horizontal resolution of the seafloor. Typically, SAS data has been visualized as 2D images or gridded 2.5D surfaces, but it can also be plotted ... -
Adaptive phase estimation filter in long range synthetic aperture sonar interferometry
Sæbø, Torstein Olsmo; Hansen, Roy Edgar (2023-05-15)Synthetic aperture sonar (SAS) interferometry is a technique for very high resolution imaging and mapping of the seabed. In SAS interferometry, the seabed depth estimation performance is a function of the system, the ... -
Automatic detection of marine gas seeps using an interferometric sidescan sonar
Blomberg, Ann Elisabeth Albright; Sæbø, Torstein Olsmo; Hansen, Roy Edgar; Pedersen, Rolf B.; Austeng, Andreas (2016)There is a significant need for reliable, cost-effective, and preferably automatic methods for detecting and monitoring marine gas seeps. Seeps at the seafloor may originate from natural sources including sediments releasing ... -
Bayesian seabed classification using angle-dependent backscatter data from multibeam echo sounders
Landmark, Knut; Solberg, Anne H Schistad; Austeng, Andreas; Hansen, Roy Edgar (2014)Acoustical seabed classification is a technology for mapping seabed sediments. Processed multibeam sonar data yield the variation of the seabed scattering strength with incidence angle, and this paper examines the effect ... -
Challenges in Seafloor Imaging and Mapping With Synthetic Aperture Sonar
Hansen, Roy Edgar; Callow, Hayden John; Sæbø, Torstein Olsmo; Synnes, Stig Asle Vaksvik (2011)Synthetic aperture sonar (SAS) is emerging as an imaging technology that can provide centimeter resolution over hundreds-of-meter range on the seafloor. Although the principle of SAS has been known for more than 30 years, ... -
Challenges of Labelling Unknown Seabed Munition Dumpsites from Acoustic and Optical Surveys: A Case Study at Skagerrak
Bryan, Oscar; Hansen, Roy Edgar; Haines, Tom S. F.; Warakagoda, Narada Dilp; Hunter, Alan Joseph (2022-05-31)The disposal of unexploded ordnance (UXOs) at sea is a global problem. The mapping and remediation of historic UXOs can be assisted by autonomous underwater vehicles (AUVs) carrying sensor payloads such as synthetic aperture ... -
Change detection on shipwrecks using synthetic aperture sonar – North Sea Wrecks Task 3.5 Deep Water Case Study
Hansen, Roy Edgar (2022-12-16)During the last 15 years, synthetic aperture sonar (SAS) technology has matured substantially. Today SAS represents state-of-the-art in seabed imaging and mapping when used on autonomous underwater vehicles (AUV). SAS ... -
Comparison of synthetic aperture sonar images and optical images of UXOs from the Skagerrak chemical munitions dumpsite
Hansen, Roy Edgar; Geilhufe, Marc; Bakken, Erik Makino; Sæbø, Torstein Olsmo (2019-11-28)After World War II chemical munitions were loaded onto large ships and sunk in the Skagerrak Strait in the Norwegian trench, in deep waters between Norway and Denmark. In collaboration with the Norwegian Coastal Administration, ... -
Data-Driven Autocalibration for Swath Sonars
Lønmo, Tor Inge Birkenes; Austeng, Andreas; Hansen, Roy Edgar (2020-12-20)Sidelobes in swath sonar water column imagery can obscure targets of interest and create erroneous bottom detections. Differences between ideal and actual element responses limit the achievable sidelobe level for practical ... -
Detection of Point Scatterers in Medical Ultrasound
Thon, Stine Hverven; Hansen, Roy Edgar; Austeng, Andreas (2021-11-19)We present an overview of the detection of point scatterers in ultrasound images and suggest strategies for evaluating and measuring the detection performance. We use synthetic aperture Field II simulations of a point ... -
The Effect of Internal Wave-Related Features on Synthetic Aperture Sonar
Hansen, Roy Edgar; Lyons, Anthony P.; Sæbø, Torstein Olsmo; Callow, Hayden John; Cook, Daniel A. (2015)In October 2012, the Centre for Maritime Research and Experimentation (CMRE, La Spezia, Italy) conducted trials from the NATO research vessel (RV) Alliance, off Elba Island, Italy. During this trial, data were collected ... -
Interference rejection for sonars via low,complexity adaptive beamforming
Lønmo, Tor Inge Birkenes; Austeng, Andreas; Hansen, Roy Edgar (2015) -
Interferometric Synthetic Aperture Sonar in Pipeline Inspection
Hansen, Roy Edgar; Sæbø, Torstein Olsmo; Callow, Hayden John; Hagen, Per Espen (2010-10-14)Accurate and reliable inspection of subsea pipelinestraditionally requires the use of multiple sensors, which againhave different requirements for range and geometry. This makespipeline inspection a time consuming and ... -
Low-Complexity Adaptive Sonar Imaging
Buskenes, Jo Inge; Hansen, Roy Edgar; Austeng, Andreas (2016)We have studied the low-complexity adaptive (LCA) beamformer in active sonar imaging. LCA can be viewed as either a simplification of the minimum variance distortionless response (MVDR) beamformer, or as an adaptive extension ... -
MIMO synthetic aperture sonar: Benefits and limitations
Hansen, Roy Edgar (2023-01-16)The use of Multiple Input Multiple Output (MIMO) orthogonally coded waveforms sharing the same bandwidth, has the potential to increase area coverage rate in synthetic aperture sonar (SAS). The disadvantage is cross-talk ... -
Modeling the effect of random roughness on synthetic aperture sonar image statistics
Lyons, Anthony P.; Olson, Derek R.; Hansen, Roy Edgar (2022-09-02)A model has been developed to predict the effect of random seafloor roughness on synthetic aperture sonar (SAS) image statistics, based on the composite roughness approximation–a physical scattering model. The continuous ... -
Multibeam Echosounder With Orthogonal Waveforms: Feasibility and Potential Benefits
Blachet, Antoine; Austeng, Andreas; Aparicio, Joaquin; Hunter, Alan Joseph; Hansen, Roy Edgar (2021-04-15)Modern multibeam echosounders (MBE) employ frequency-division techniques (FDT) to ensonify multiple sectors within the same ping cycle. This leads to improved performance in coverage rate, and yaw and pitch stabilization. ... -
The Multivariate Normal Inverse Gaussian distribution: EM-estimation and analysis of synthetic aperture sonar data
Øigård, Tor Arne; Hanssen, Alfred; Hansen, Roy Edgar (2015)The heavy-tailed Multivariate Normal Inverse Gaussian (MNIG) distribution is a recent variance-mean mixture of a multivariate Gaussian with a univariate inverse Gaussian distribution. Due to the complexity of the ... -
A new approach to high-resolution seafloor mapping
Callow, Hayden John; Hagen, Per Espen; Hansen, Roy Edgar; Sæbø, Torstein Olsmo; Pedersen, Rolf B. (2012) -
A new method for underwater archaeological surveying using sensors and unmanned platforms
Ødegård, Øyvind; Sørensen, Asgeir Johan; Hansen, Roy Edgar; Ludvigsen, Martin (2016)As most of the world’s oceans are inaccessible to diving archaeologists, we must rely on advanced underwater technology and marine robotics to explore, map and investigate ship wrecks in these areas. New sensors and unmanned ...