Détail de l'auteur
Auteur J. Nichol |
Documents disponibles écrits par cet auteur (3)
Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externes
Potential of texture measurements of two-date dual polarization PALSAR data for the improvement of forest biomass estimation / M. Sarker in ISPRS Journal of photogrammetry and remote sensing, vol 69 (April 2012)
[article]
Titre : Potential of texture measurements of two-date dual polarization PALSAR data for the improvement of forest biomass estimation Type de document : Article/Communication Auteurs : M. Sarker, Auteur ; J. Nichol, Auteur ; B. Ahmad, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 146 - 166 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] biomasse
[Termes IGN] Hong-Kong
[Termes IGN] image ALOS-PALSAR
[Termes IGN] image radar moirée
[Termes IGN] polarimétrie radar
[Termes IGN] polarisation
[Termes IGN] texture d'imageRésumé : (Auteur) The recently available space-borne SAR sensor, PALSAR, is more promising than its predecessor JERS-1 for biomass estimation because of its long wavelength (L-band), and its ability to provide data with different polarizations, varying incidence angles and higher spatial resolutions. This research investigates the potential of two-date dual polarization (HH and HV) SAR imagery for biomass estimation using different kinds of texture processing and different combinations of single and dual polarization ratios. The investigation is conducted in a mountainous, sub-tropical study area where biomass levels are far beyond the previously recognized saturation levels for L-band SAR images, and forest is a mixture of native and non-native species and plantations. We analyzed two-date SAR data with four steps of image processing, including raw data processing in various combinations, texture measurement parameters of HH and HV polarizations, texture measurement parameters of HH and HV together (both jointly and as a ratio), and a ratio of two-date texture parameters along with a single and two-date ratio. When the processed images were compared with ground data from 50 plots, the performance from raw data processing was low, with adjusted r2 = 0.22, but after all four processing steps, promising model accuracy (adjusted r2 = 0.90 and RMSE = 28.58 t/ha) and validation accuracy (using the Leave-One-Out-Cross-Validation) with adjusted r2 = 0.88 and RMSE = 35.69 t/ha, were achieved from the combination of single- and two-date polarization ratios of texture parameters. The strong performance achieved indicates that L-band dual-polarization (HH and HV) SAR data from PALSAR has great potential for biomass estimation, far beyond the previously reported L-band saturation point for biomass. This result is attributed to the synergy among texture processing and dual polarization on the one hand, which were able to average out random speckle noise, and the use of ratio instead of absolute quantities, due to its well known ability to reduce forest structural and terrain effects. The additional use of two-date SAR data with these processing techniques was able to add complementary information derived from biomass response in both wet and dry seasons. Thus overall, undesirable image noise and terrain effects were reduced. Numéro de notice : A2012-198 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2012.03.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2012.03.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31645
in ISPRS Journal of photogrammetry and remote sensing > vol 69 (April 2012) . - pp 146 - 166[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2012031 SL Revue Centre de documentation Revues en salle Disponible Potential accuracy of image orientation of small satellites: a case study of CHRIS/Proba data / Ahmed Shaker in Photogrammetric record, vol 23 n° 123 (September - November 2008)
[article]
Titre : Potential accuracy of image orientation of small satellites: a case study of CHRIS/Proba data Type de document : Article/Communication Auteurs : Ahmed Shaker, Auteur ; J. Nichol, Auteur ; M. Wong, Auteur Année de publication : 2008 Conférence : ISPRS 2007, High-Resolution Earth Imaging for Geospatial Information workshop 29/05/2007 01/06/2007 Hanovre Allemagne Article en page(s) : pp 275 - 289 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie spatiale
[Termes IGN] angle de visée
[Termes IGN] correction géométrique
[Termes IGN] espace image
[Termes IGN] espace objet
[Termes IGN] géoréférencement
[Termes IGN] Hong-Kong
[Termes IGN] image hyperspectrale
[Termes IGN] image PROBA-CHRIS
[Termes IGN] minisatellite
[Termes IGN] modèle empirique
[Termes IGN] modèle stéréoscopique
[Termes IGN] montagne
[Termes IGN] orientation d'image
[Termes IGN] point d'appui
[Termes IGN] précision géométrique (imagerie)Résumé : (Auteur) The new technology of small satellites (microsatellites) opens a new era in satellite observation of the earth. Small satellites such as ESA's Project for On-Board Autonomy (Proba), launched on 22nd October 2001, are of interest due to their low cost, flexibility of positioning, and capability for multiangular scanning in both across-track and along-track directions. Proba's Compact High Resolution Imaging Spectrometer (CHRIS) provides multidirectional, as well as hyperspectral, data at 18 m resolution and is supplied mainly to the scientific community for experimental environmental applications. This research evaluates the use of various empirical mathematical models for small satellite orientation and terrain modelling using the multidirectional viewing capabilities of CHRIS data. Geometric correction and co-registration of multiangle images is essential for their use for data extraction. Ideally, rigorous mathematical models should be formulated which precisely describe the satellite motion and represent the relationship between the image and the object spaces. The use of rigorous mathematical models has not been fully investigated using CHRIS/Proba data, because the satellite information provided is not adequate for rigorous sensor modelling. In this paper, several alternative empirical models are tested for the orientation and 3D geopositioning of CHRIS sensor images. The images used in this study cover extremely mountainous terrain in central Hong Kong. A set of five images from CHRIS/Proba taken in December 2005 from different angles are used to test the applicability of different forms of the empirical models for 3D geopositioning. The accuracy of the models is tested for different numbers and distribution of ground control points (GCPs) using different combinations of observation angles and base-to-height ratios. The results obtained show high integrity of the models used for CHRIS/Proba image orientation. In some cases, accuracy better than 2 pixels can be achieved using a modest number of GCPs. Copyright RS&PS + Blackwell Publishing Numéro de notice : A2008-393 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2008.00490.x En ligne : https://doi.org/10.1111/j.1477-9730.2008.00490.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29386
in Photogrammetric record > vol 23 n° 123 (September - November 2008) . - pp 275 - 289[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 106-08031 RAB Revue Centre de documentation En réserve L003 Disponible Satellite remote sensing for detailed landslide inventories using change detection and image fusion / J. Nichol in International Journal of Remote Sensing IJRS, vol 26 n° 9 (May 2005)
[article]
Titre : Satellite remote sensing for detailed landslide inventories using change detection and image fusion Type de document : Article/Communication Auteurs : J. Nichol, Auteur ; M.S. Wong, Auteur Année de publication : 2005 Article en page(s) : pp 1913 - 1926 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] classification par maximum de vraisemblance
[Termes IGN] détection de changement
[Termes IGN] effondrement de terrain
[Termes IGN] fusion d'images
[Termes IGN] image Ikonos
[Termes IGN] image multitemporelle
[Termes IGN] image SPOT XS
[Termes IGN] surveillance géologiqueRésumé : (Auteur) The availability of high spatial and spectral resolution remote sensing systems may be accompanied by changes in techniques for applying the data if appropriate data processing methodologies can be demonstrated. Landslide monitoring, which requires large areas to be surveyed at a detailed level, has previously been unsatisfactory due to its reliance on air photograph interpretation. This study demonstrates the synergistic use of medium resolution, multitemporal Satellite pour I'Observation de la Terre (SPOT) XS, and fine resolution IKONOS images for landslide inventories. The post-classification comparison method of change detection using the Maximum Likelihood classifier with SPOT XS images was able to detect approximately 70% of landslides, the main omissions being those smaller than approximately half a pixel wide. The visual quality of images obtained from Pan-sharpening of IKONOS images was comparable to that obtainable from 1:10000 scale air photographs, enabling detailed interpretation of landslides and associated environmental features. A methodology combining the two levels of survey is proposed for regional scale landslide monitoring. Numéro de notice : A2005-257 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160512331314047 En ligne : https://doi.org/10.1080/01431160512331314047 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27393
in International Journal of Remote Sensing IJRS > vol 26 n° 9 (May 2005) . - pp 1913 - 1926[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-05091 RAB Revue Centre de documentation En réserve L003 Exclu du prêt