English
norskBlar i forfatter "Doulgeris, Anthony Paul"
Viser treff 41-58 av 58
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On the relation between polarimetric synthetic aperture radar (SAR) features and sea ice melt pond fraction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-12)In this study we examine the relationship between sea ice melt pond fraction and two polarimetric C-band synthetic aperture radar (SAR) features. Three high-resolution SAR scenes were recorded in the Fram Strait in late summer 2011, covering iceberg-fast first-year and old sea ice. In addition, melt pond fraction was retrieved from photographs recorded during a helicopter flight at the study area. ... -
An Optimal Decision-Tree Design Strategy and Its Application to Sea Ice Classification from SAR Imagery
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-03)We introduce the fully automatic design of a numerically optimized decision-tree algorithm and demonstrate its application to sea ice classification from SAR data. In the decision tree, an initial multi-class classification problem is split up into a sequence of binary problems. Each branch of the tree separates one single class from all other remaining classes, using a class-specific selected feature ... -
Polarimetric SAR Change Detection with the Complex Hotelling-Lawley Trace Statistic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-03-15)In this paper, we propose a new test statistic for unsupervised change detection in polarimetric radar images. We work with multilook complex covariance matrix data, whose underlying model is assumed to be the scaled complex Wishart distribution. We use the complex-kind Hotelling-Lawley trace statistic for measuring the similarity of two covariance matrices. The distribution of the Hotelling-Lawley ... -
Quad-Polarimetric SAR for Detection and Characterization of Icebergs
(Conference object; Konferansebidrag, 2016)This paper evaluates the performance of fully polarimetric SAR data in iceberg detection and characterization. The study aims to explore the potential of RADARSAT-2 SAR data to detect icebergs and growlers in Svalbard that have broken off from the glaciers nearby. To be able to detect iceberg/growlers in a SAR image, a significant contrast between iceberg and background clutter is required. The ... -
Robustness of SAR Sea Ice Type classification across incidence angles and seasons at L-band
(Journal article; Tidsskriftartikkel, 2020-11-16)In recent years, space-borne synthetic aperture radar (SAR) polarimetry has become a valuable tool for sea ice type retrieval. L-band SAR has proven to be sensitive toward deformed sea ice and is complementary compared with operationally used C-band SAR for sea ice type classification during the early and advanced melt seasons. Here, we employ an artificial neural network (ANN)-based sea ice type ... -
Sea ice classification of TerraSAR-X ScanSAR images for the MOSAiC expedition incorporating per-class incidence angle dependency of image texture
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-16)We provide sea ice classification maps of a subweekly time series of single (horizontal–horizontal, HH) polarization X-band TerraSAR-X scanning synthetic aperture radar (TSX SC) images from November 2019 to March 2020, covering the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. This classified time series benefits from the wide spatial coverage ... -
Sea ice segmentation using Tandem-X pursuit mono static and alternative bistatic modes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-04)In this paper we investigate interferometric pairs of SAR images acquired by Tandem-X with the monostatic pursuit and the alternative bistatic modes for sea ice segmentation. The individual SAR images are modelled as non-Gaussian, and from the modelled data different features are extracted, stacked together and clustered. The interferometric coherence is regarded as an additional feature and utilized ... -
A Segmentation based CFAR detection algorithm using truncated statistics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-18)Target detection in nonhomogeneous sea clutter environments is a complex and challenging task due to the capture effect from interfering outliers and the clutter edge effect from background intensity transitions. For synthetic aperture radar (SAR) measurements, those issues are commonly caused by multiple targets and meteorological and oceanographic phenomena, respectively. This paper proposes a ... -
Signature of Arctic first-year ice melt pond fraction in X-band SAR imagery
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-23)In this paper we investigate the potential of melt pond fraction retrieval from X-band polarimetric synthetic aperture radar (SAR) on drifting first-year sea ice. Melt pond fractions retrieved from a helicopter-borne camera system were compared to polarimetric features extracted from four dual-polarimetric X-band SAR scenes, revealing significant relationships. The correlations were strongly dependent ... -
A Simple and Extendable Segmentation Method for Multi-Polarisation SAR Images
(Conference object; Konferansebidrag, 2013)This work presents a simple feature-based multi-channel SAR segmentation method that produces good, smooth, fast and robust results for image segmentation and interpretation. A basic set of six features produce good class distinction for general applications, and the method is easily extendable with new features and for multi-source data fusion. Optional steps of sub-sampling and Markov Random ... -
Speeding Up Non-Gaussian POLSAR Image Analysis
(Journal article; Peer reviewed, 2017-12-04)Non-Gaussian statistical models fit SAR data better than Gaussian-based statistics, in most cases, but are complicated and time-consuming to use for unsupervised image segmentation via probabilistic clustering. The more advanced the model, the more complicated and slow the clustering. The U-distribution has been demonstrated to be one of the most flexible models, capturing the Gaussian/Wishart, the ... -
Statistical modelling of polarimetric SAR data
(Master thesis; Mastergradsoppgave, 2006-06-02)A statistical modelling technique is developed to analyse polarimetric synthetic aperture radar (PolSAR) images. Polarimetric SAR data consists of four complex scattering coefficients at each image location, requiring multivariate modelling techniques, and this work focuses on a simple class of multivariate distributions, the scale mixture of Gaussians. Three parametric model families of that ... -
Subaperture analysis of polarimetric SAR data for iceberg detection
(Konferansebidrag; Conference object, 2016-11-03)This paper is focused on investigations of the improved detection of icebergs in open water using spectral analysis of polarimetric SAR data. The objectives of this study are to analyze the behavior of ice objects in open water using the sublook cross-correlation magnitude (SCM). It is shown that there is an improvement of iceberg-sea contrast when the SCM is used instead of multilook intensities ... -
A Textural–Contextual Model for Unsupervised Segmentation of Multipolarization Synthetic Aperture Radar Images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)This paper proposes a novel unsupervised, non-Gaussian, and contextual segmentation method that combines an advanced statistical distribution with spatial contextual informa-tion for multilook polarimetric synthetic aperture radar (PolSAR)data. This extends on previous studies that have shown the added value of both non-Gaussian modeling and contextual smoothing individually or for intensity channels ... -
Towards automatic detection of dark features in the Barents Sea using synthetic aperture radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-17)Increased human presence and commercial activities in the Barents Sea (fishing, offshore oil and gas exploration) are amplifying the need for large-scale operational ocean monitoring of the eventual oil spills in the region. The geographical location and climate impose additional constraints on satellite-based monitoring, making it necessary to use Synthetic Aperture Radar (SAR). Dark features or ... -
Towards operational sea ice type retrieval using L-band Synthetic aperture radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)Operational ice services around the world have recognized the economic and environmental benefits that come from the increased capabilities and uses of space-borne Synthetic Aperture Radar (SAR) observation system. The two major objectives in SAR based remote sensing of sea ice is on the one hand to have a large areal coverage, and on the other hand to obtain a radar response that carries as much ... -
An unsupervised method for equivalent number of looks estimation in complex SAR scenes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-12)This paper introduces a novel unsupervised estimator of equivalent number of looks (ENL) that can be applied to an arbitrary image. It avoids the assumption that homogeneous speckle will dominate the investigated image that is followed by current unsupervised ENL estimators but not always valid, especially for the complex SAR scenes with high mixture and texture. Incorporating the statistical ... -
Unsupervised Mixture-Eliminating Estimation of Equivalent Number of Looks for PolSAR Data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-22)This paper addresses the impact of mixtures between classes on equivalent number of looks (ENL) estimation. We propose an unsupervised ENL estimator for polarimetric synthetic aperture radar (PolSAR) data, which is based on small sample estimates but incorporates a mixture-eliminating (ME) procedure to automatically assess the uniformity of the estimation windows. A statistical feature derived from ...
