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Active-metric learning for classification of remotely sensed hyperspectral images / Edoardo Pasolli in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 1925 - 1939 Titre : Active-metric learning for classification of remotely sensed hyperspectral images Type de document : Article/Communication Auteurs : Edoardo Pasolli, Auteur ; Hsiuhan Lexie Yang, Auteur ; Melba M. Crawford, Auteur Année de publication : 2016 Article en page(s) : pp 1925 - 1939 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] apprentissage automatique [Termes IGN] classification barycentrique [Termes IGN] classification dirigée [Termes IGN] extraction automatique [Termes IGN] extraction de traits caractéristiques Résumé : (Auteur) Classification of remotely sensed hyperspectral images via supervised approaches is typically affected by high dimensionality of the spectral data and a limited number of labeled samples. Dimensionality reduction via feature extraction and active learning (AL) are two approaches that researchers have investigated independently to deal with these two problems. In this paper, we propose a new method in which the feature extraction and AL steps are combined into a unique framework. The idea is to learn and update a reduced feature space in a supervised way at each iteration of the AL process, thus taking advantage of the increasing labeled information provided by the user. In particular, the computation of the reduced feature space is based on the large-margin nearest neighbor (LMNN) metric learning principle. This strategy is applied in conjunction with k-nearest neighbor ( k-NN) classification, for which a new sample selection strategy is proposed. The methodology is validated experimentally on four benchmark hyperspectral data sets. Good improvements in terms of classification accuracy and computational time are achieved with respect to the state-of-the-art strategies that do not combine feature extraction and AL. Numéro de notice : A2016-836 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2490482 En ligne : http://dx.doi.org/10.1109/TGRS.2015.2490482 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82880 [article]

A synchronization algorithm for spaceborne/stationary BiSAR imaging based on contrast optimization with direct signal from radar satellite / M. Zhang in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 1977 - 1989 Titre : A synchronization algorithm for spaceborne/stationary BiSAR imaging based on contrast optimization with direct signal from radar satellite Type de document : Article/Communication Auteurs : M. Zhang, Auteur ; Robert Wang, Auteur ; Y. Deng, Auteur Année de publication : 2016 Article en page(s) : pp 1977 - 1989 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] amélioration du contraste [Termes IGN] image radar moirée [Termes IGN] optimisation (mathématiques) [Termes IGN] radar bistatique [Termes IGN] synchronisation Résumé : (Auteur) This paper proposes a synchronization algorithm for bistatic synthetic aperture radar (BiSAR) imaging in a spaceborne/stationary configuration. In real bistatic systems, synchronization errors are generally introduced into the received data. Additionally, the lack of precise imaging parameters, such as the position of the transmitter and the accurate sampling time, could affect the imaging quality greatly. Fortunately, the image could be well focused by the proposed algorithm in the case of lack of the accurate position of a transmitter and the sampling time. First, a preprocessing step is employed to remove synchronization errors through matching an echo signal with a direct signal. Then, a modified chirp scaling factor containing an error phase term is constructed, and the accurate position of the transmitter and the sampling time can be acquired by the phase extraction of the direct signal and the searching method based on contrast optimization. After that, the corresponding imaging process can be implemented. Finally, the proposed algorithm is validated by the simulation and experimental results, where TerraSAR-X is used as the illuminator. Numéro de notice : A2016-837 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2493078 En ligne : http://dx.doi.org/10.1109/TGRS.2015.2493078 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82881 [article]

Change detection between SAR images using a pointwise approach and graph theory / Minh-Tan Pham in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 2020 - 2032 Titre : Change detection between SAR images using a pointwise approach and graph theory Type de document : Article/Communication Auteurs : Minh-Tan Pham, Auteur ; Grégoire Mercier, Auteur ; Julien Michel, Auteur Année de publication : 2016 Article en page(s) : pp 2020 - 2032 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] bruit rose [Termes IGN] classification pixellaire [Termes IGN] détection de changement [Termes IGN] graphe [Termes IGN] image radar [Termes IGN] image radar moirée [Termes IGN] relation topologique [Termes IGN] traitement du signal [Termes IGN] voisinage (relation topologique) Résumé : (Auteur) This paper investigates the problem of change detection in multitemporal synthetic aperture radar (SAR) images. Our motivation is to avoid using a large-size dense neighborhood around each pixel to measure its change level, which is usually considered by classical methods in order to perform their accurate detectors. Therefore, we propose to develop a pointwise approach to detect land-cover changes between two SAR images employing the principle of signal processing on graphs. First, a set of characteristic points is extracted from one of the two images to capture the image's significant contextual information. A weighted graph is then constructed to encode the interaction among these keypoints and hence capture the local geometric structure of this first image. With regard to this graph, the coherence of the information carried by the two images is considered for measuring changes between them. In other words, the change level will depend on how much the second image still conforms to the graph structure constructed from the first image. Additionally, due to the presence of speckle noise in SAR imaging, the log-ratio operator will be exploited to perform the image comparison measure. Experimental results performed on real SAR images show the effectiveness of the proposed algorithm, in terms of detection performance and computational complexity, compared to classical methods. Numéro de notice : A2016-838 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2493730 En ligne : http://dx.doi.org/10.1109/TGRS.2015.2493730 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82882 [article]

Faraday rotation correction for the SMAP radiometer / David M. Le Vine in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 2070 - 2081 Titre : Faraday rotation correction for the SMAP radiometer Type de document : Article/Communication Auteurs : David M. Le Vine, Auteur ; Saji Abraham, Auteur ; Jinzheng Peng, Auteur Année de publication : 2016 Article en page(s) : pp 2070 - 2081 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] évaluation des données [Termes IGN] humidité du sol [Termes IGN] mission SMAP [Termes IGN] radiomètre [Termes IGN] rotation de Faraday [Termes IGN] Soil Moisture Active Passive [Termes IGN] surface de l'eau [Termes IGN] surface du sol Résumé : (Auteur) Faraday rotation is an important issue for remote sensing of parameters such as soil moisture and ocean salinity, which are best done at low microwave frequency (e.g., L-band). Modern instruments such as the radiometer on the Soil Moisture and Ocean Salinity (SMOS) satellite and the Aquarius radiometers include polarimetric radiometer channels specifically to implement a correction for Faraday rotation. This works well over ocean, but it is known that over inhomogeneous scenes, such as a land/water mixture, significant errors can occur. This is a particularly important issue for the newest L-band sensor in space, the radiometer on the Soil Moisture Active Passive (SMAP) satellite, where the goal is remote sensing over land (soil moisture) and where the conical scan induces rapid variation in Faraday rotation. Analysis is presented here of the issues associated with retrieving Faraday rotation using the SMAP geometry and antenna pattern. It is shown that, in addition to scenes with a mixture of land and water, scenes with significant vegetation canopy are also associated with large errors in the retrieved Faraday rotation. Examples from the SMAP radiometer support the analysis. Numéro de notice : A2016-839 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2495168 En ligne : https://doi.org/10.1109/TGRS.2015.2495168 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82883 [article]

Robust locally weighted regression techniques for ground surface points filtering in mobile laser scanning three dimensional point cloud data / Abdul Nurunnabi in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 2181 - 2193 Titre : Robust locally weighted regression techniques for ground surface points filtering in mobile laser scanning three dimensional point cloud data Type de document : Article/Communication Auteurs : Abdul Nurunnabi, Auteur ; Geoff West, Auteur ; David Belton, Auteur Année de publication : 2016 Article en page(s) : pp 2181 - 2193 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] ajustement de paramètres [Termes IGN] algorithme de filtrage [Termes IGN] analyse comparative [Termes IGN] analyse de données [Termes IGN] extraction de points [Termes IGN] régression [Termes IGN] segmentation d'image [Termes IGN] semis de points [Termes IGN] télémétrie laser mobile [Termes IGN] zone urbaine Résumé : (Auteur) This paper introduces robust algorithms for extracting the ground points in laser scanning 3-D point cloud data. Global polynomial functions have been used for filtering algorithms for point cloud data; however, it is not suitable as it may lead to bias for the filtering algorithms and can cause misclassification errors when many different objects are present. In this paper, robust statistical approaches are coupled with locally weighted 2-D regression that fits without any predefined global function for the variables of interest. Algorithms are performed iteratively on 2-D profiles: x - z and y - z. The z (elevation) values are robustly down weighted based on the residuals for the fitted points. The new set of down-weighted z values, along with the corresponding x (or y) values, is used to get a new fit for the lower surface level. The process of fitting and down weighting continues until the difference between two consecutive fits is insignificant. The final fit is the required ground level, and the ground surface points are those that fall within the ground level and the level after adding some threshold value with the ground level for z values. Experimental results are compared with the recently proposed segmentation method through simulated and real mobile laser scanning point clouds from urban areas that include many objects that appear in road scenes such as short walls, large buildings, electric poles, signposts, and cars. Results show that the proposed robust methods efficiently extract ground surface points with better than 97% accuracy. Numéro de notice : A2016-840 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2496972 En ligne : http://dx.doi.org/10.1109/TGRS.2015.2496972 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82884 [article]

Interferometric processing of Sentinel-1 TOPS Data / Néstor Yagüe-Martínez in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 2220 - 2234 Titre : Interferometric processing of Sentinel-1 TOPS Data Type de document : Article/Communication Auteurs : Néstor Yagüe-Martínez, Auteur ; Pau Prats-Iraola, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 2220 - 2234 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] effet Doppler [Termes IGN] élément orbital [Termes IGN] image radar moirée [Termes IGN] image Sentinel-SAR [Termes IGN] Image TOPS [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] largeur de bande Résumé : (Auteur) Sentinel-1 (S-1) has an unparalleled mapping capacity. In interferometric wide swath (IW) mode, three subswaths imaged in the novel Terrain Observation by Progressive Scans (TOPS) SAR mode result in a total swath width of 250 km. S-1 has become the European workhorse for large area mapping and interferometric monitoring at medium resolution. The interferometric processing of TOPS data however requires special consideration of the signal properties, resulting from the ScanSAR-type burst imaging and the antenna beam steering in azimuth. The high Doppler rate in azimuth sets very stringent coregistration requirements, making the use of enhanced spectral diversity (ESD) necessary to obtain the required fine azimuth coregistration accuracy. Other unique aspects of processing IW data, such as azimuth spectral filtering, image resampling, and data deramping and reramping, are reviewed, giving a recipe-like description that enables the user community to use S-1 IW mode repeat-pass SAR data. Interferometric results from S-1A are provided, demonstrating the mapping capacity of the S-1 system and its interferometric suitability for geophysical applications. An interferometric evaluation of a coherent interferometric pair over Salar de Uyuni, Bolivia, is provided, where several aspects related to coregistration, deramping, and synchronization are analyzed. Additionally, a spatiotemporal evaluation of the along-track shifts, which are directly related to the orbital/instrument timing error, measured from the SAR data is shown, which justifies the necessity to refine the azimuth shifts with ESD. The spatial evaluation indicates high stability of the azimuth shifts for several slices of a datatake. Numéro de notice : A2016-841 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2497902 En ligne : https://doi.org/10.1109/TGRS.2015.2497902 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82885 [article]

Band-limited signal reconstruction from irregular samples with variable apertures / David G. Long in IEEE Transactions on geoscience and remote sensing, vol 54 n° 4 (April 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 4 (April 2016) . - pp 2424 - 2436 Titre : Band-limited signal reconstruction from irregular samples with variable apertures Type de document : Article/Communication Auteurs : David G. Long, Auteur ; Reinhard O. W. Franz, Auteur Année de publication : 2016 Article en page(s) : pp 2424 - 2436 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] échantillonnage de signal [Termes IGN] largeur de bande [Termes IGN] reconstruction d'image [Termes IGN] reconstruction du signal [Termes IGN] télédétection Résumé : (Auteur) Sampling plays a critical role in remote sensing and signal analysis. In conventional sampling theory, the signal is sampled at a uniform rate at a minimum of twice the signal bandwidth. Sampling with an aperture function requires a fixed-aperture function, which can be removed by deconvolution after signal reconstruction. However, in some cases, the signal samples are available only at irregular positions, and different samples use different aperture functions. In this paper, the theory of finite-length signal reconstruction with irregular samples and variable apertures in one and two dimensions is considered. In the 1-D case, a band-limited discrete signal can be exactly reconstructed from a finite number of arbitrarily spaced samples with few restrictions on the aperture functions. Exact reconstruction in the 2-D case requires the sampling matrix be invertable, and is not always possible. Variable aperture functions, while complicating the process, can enable reconstruction for a broader range of sample locations. Practical issues are discussed, and numerical examples are provided. Variable aperture reconstruction has application in a variety of remote sensing problems. In this paper, reconstruction from 2-D irregular sampling with variable apertures is illustrated using Special Sensor Microwave/Imager radiometer observations. Numéro de notice : A2016-842 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2015.2501366 En ligne : http://dx.doi.org/10.1109/TGRS.2015.2501366 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82886 [article]