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Time-geographic derivation of feasible co-presence opportunities from network-constrained episodic movement data / Mathias Versichele in Transactions in GIS, vol 18 n° 5 (October 2014)
[article]
Titre : Time-geographic derivation of feasible co-presence opportunities from network-constrained episodic movement data Type de document : Article/Communication Auteurs : Mathias Versichele, Auteur ; T. Neutens, Auteur ; Manuel Claeys Boùùaert, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 687 – 703 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] analyse spatio-temporelle
[Termes IGN] Bluetooth
[Termes IGN] capteur passif
[Termes IGN] implémentation (informatique)
[Termes IGN] milieu urbain
[Termes IGN] objet mobile
[Termes IGN] réseau routierRésumé : (Auteur) Certain datasets on moving objects are episodic in nature – that is, the data is characterized by time gaps during which the position of the object is unknown. In this article, a model is developed to study the sparsely sampled network-constrained movement of several objects by calculating both potential and feasible (i.e. more likely) co-presence opportunities over time. The approach is applied to the context of a static sensor network, where the location of an object is only registered when passing a sensor location along a road network. Feasibility is incorporated based on the deviation from the shortest path. As an illustration, the model is applied to a large Bluetooth tracking dataset gathered at a mass event. The model output consists of maps showing the temporal evolution of the distribution of feasible co-presence opportunities of tracked visitors over the network (i.e. the number of visitors that could have been present together). We demonstrate the model's usefulness in studying the movement and distribution of a crowd over a study area with relatively few sampling locations. Finally, we discuss the results with a special emphasis on the distinction between feasible and actual presence, the need for further validation and calibration, and the performance of the implementation. Numéro de notice : A2014-510 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/URBANISME Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12050 Date de publication en ligne : 12/09/2013 En ligne : https://doi.org/10.1111/tgis.12050 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74109
in Transactions in GIS > vol 18 n° 5 (October 2014) . - pp 687 – 703[article]Assessing the potential for leaf-off LiDAR data to model canopy closure in temperate deciduous forests / Jason R. Parent in ISPRS Journal of photogrammetry and remote sensing, vol 95 (September 2014)
[article]
Titre : Assessing the potential for leaf-off LiDAR data to model canopy closure in temperate deciduous forests Type de document : Article/Communication Auteurs : Jason R. Parent, Auteur ; John C. Volin, Auteur Année de publication : 2014 Article en page(s) : pp 134 – 145 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] canopée
[Termes IGN] données lidar
[Termes IGN] feuillu
[Termes IGN] forêt
[Termes IGN] objectif grand angulaire
[Termes IGN] photographie aérienne
[Termes IGN] télémétrie laser aéroportéRésumé : (Auteur) Estimates of canopy closure have many important uses in forest management and ecological research. Field measurements, however, are typically not practical to acquire over expansive areas or for large numbers of locations. This problem has been addressed, in recent years, through the use of airborne light detection and ranging (LiDAR) technology which has proven effective in modeling canopy closure remotely. The techniques developed to use LiDAR for this purpose have been designed and evaluated for datasets acquired during leaf-on conditions. However, a large number of LiDAR datasets are acquired during leaf-off conditions since their primary purpose is to generate bare-earth Digital Elevation Models. In this paper, we develop and evaluate techniques for leveraging small-footprint leaf-off LiDAR data to model leaf-on canopy closure in temperate deciduous forests.
We evaluate three techniques for modeling canopy closure: (1) the canopy-to-total-return-ratio (CTRR), (2) the canopy-to-total-pixel-ratio (CTPR), and (3) the hemispherical-viewshed (HV). The first technique has been used widely, in various forms, and has been shown to be effective with leaf-on LiDAR datasets. The CTRR technique that we tested uses the first-return LiDAR data only. The latter two techniques are new contributions that we develop and present in this paper. These techniques use Canopy Height Models (CHM) to detect significant gaps in the forest canopy which are of primary importance in estimating closure.
The techniques we tested each showed good promise for predicting canopy closure using leaf-off LiDAR data with the CTPR and HV models having particularly high correlations with closure estimates from hemispherical photographs. The CTRR model had performance on par with results from previous studies that used leaf-on LiDAR, although, with leaf-off data the model tended to be negatively biased with respect to species having simple and compound leaf types and positively biased for coniferous species. The CTPR and HV models also showed some slight negative biases for compound-leaf species. The biases for the CTPR and HV models were mitigated when the CHM data were smoothed to fill in small gaps. The CHM-based models were robust to changes in the CHM model resolution which suggests that these methods may be applicable to a variety of small-footprint LiDAR datasets. In this research, the new CTPR and HV methods showed a strong ability to predict canopy closure using leaf-off data, however, future work will be needed to test the applicability of the models to variations in LiDAR datasets, forest types, and topography.Numéro de notice : A2014-477 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2014.06.009 En ligne : https://doi.org/10.1016/j.isprsjprs.2014.06.009 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74054
in ISPRS Journal of photogrammetry and remote sensing > vol 95 (September 2014) . - pp 134 – 145[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2014091 RAB Revue Centre de documentation En réserve L003 Disponible Error analysis of a mobile terrestrial LiDAR system / M. Leslar in Geomatica, vol 68 n° 3 (September 2014)
[article]
Titre : Error analysis of a mobile terrestrial LiDAR system Type de document : Article/Communication Auteurs : M. Leslar, Auteur ; B. Hu, Auteur ; J.G. Wang, Auteur Année de publication : 2014 Article en page(s) : pp 183 - 194 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] analyse de sensibilité
[Termes IGN] capteur terrestre
[Termes IGN] centrale inertielle
[Termes IGN] données lidar
[Termes IGN] lasergrammétrie
[Termes IGN] lidar mobile
[Termes IGN] navigation inertielle
[Termes IGN] propagation d'erreur
[Termes IGN] semis de points
[Termes IGN] système de numérisation mobile
[Termes IGN] télémètre laser terrestreIndex. décimale : 33.80 Lasergrammétrie Résumé : (Auteur) La compréhension des effets des erreurs sur les nuages de points du LiDAR terrestre mobile (MTL) n'a pas augmenté avec sa popularité. Dans le présent article, nous avons effectué des analyses globales des erreurs fondées sur la théorie de propagation des erreurs et une étude globale de la sensibilité dans le but de décrire quantitativement les effets, sur le nuage de points, de diverses sources d'erreurs dans un système MTL. Nous avons envisagé deux scénarios, le premier utilisant les incertitudes dans les variables de mesure et de calibration qui sont normalement attendues pour les systèmes MTL qui existent actuellement et le second utilisant une situation idéale où les valeurs de mesure et de calibration ont été bien ajustées. Il a été établi que la proportion la plus élevée d'erreurs dans le nuage de points peut être attribuée aux paramètres de visée et de levier pour les systèmes MTL calibrés en utilisant des méthodes non rigoureuses. Plus particulièrement, dans une condition d'erreurs mal contrôlées, le levier entre le LiDAR et l'axe Z du INS (système de navigation par inertie) et l'angle de roulis entre le LiDAR et l'INS ont contribué à des erreurs plus grandes dans le nuage de points résultant que tout autre paramètre, y compris la position du INS. Dans des conditions d'erreurs fortement contrôlées, la position du INS est devenue la principale source d'erreurs dans le nuage de points. De plus, l'analyse de la variance conditionnelle a démontré que la majorité des erreurs dans un nuage de points peut être attribuée aux variables individuelles. Les erreurs causées par les interactions entre les diverses variables sont minimes et peuvent être considérées comme négligeables. Numéro de notice : A2014-622 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : 10.5623/cig2014-303 En ligne : https://doi.org/10.5623/cig2014-303 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75001
in Geomatica > vol 68 n° 3 (September 2014) . - pp 183 - 194[article]Kernel sparse multitask learning for hyperspectral image classification with empirical mode decomposition and morphological wavelet-based features / Z. He in IEEE Transactions on geoscience and remote sensing, vol 52 n° 8 Tome 2 (August 2014)
[article]
Titre : Kernel sparse multitask learning for hyperspectral image classification with empirical mode decomposition and morphological wavelet-based features Type de document : Article/Communication Auteurs : Z. He, Auteur ; Qiang Wang, Auteur ; Y. Shen, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 5150 -5163 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] classificateur
[Termes IGN] décomposition en fonctions orthogonales empiriques
[Termes IGN] image hyperspectrale
[Termes IGN] pouvoir de résolution géométrique
[Termes IGN] pouvoir de résolution spectrale
[Termes IGN] précision de la classification
[Termes IGN] transformation en ondelettesRésumé : (Auteur) Recently, many researchers have attempted to exploit spectral-spatial features and sparsity-based hyperspectral image classifiers for higher classification accuracy. However, challenges remain for efficient spectral-spatial feature generation and combination in the sparsity-based classifiers. This paper utilizes the empirical mode decomposition (EMD) and morphological wavelet transform (MWT) to gain spectral-spatial features, which can be significantly integrated by the sparse multitask learning (MTL). In the feature extraction step, the sum of the intrinsic mode functions extracted by an optimized EMD is taken as spectral features, whereas the spatial features are formed by the low-frequency components of one-level MWT. In the classification step, a kernel-based sparse MTL solved by the accelerated proximal gradient is applied to analyze both the spectral and spatial features simultaneously. Experiments are conducted on two benchmark data sets with different spectral and spatial resolutions. It is found that the proposed methods provide more accurate classification results compared to the state-of-the-art techniques with various ratio of training samples. Numéro de notice : A2014-436 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2013.2287022 En ligne : https://doi.org/10.1109/TGRS.2013.2287022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=73973
in IEEE Transactions on geoscience and remote sensing > vol 52 n° 8 Tome 2 (August 2014) . - pp 5150 -5163[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 065-2014081B RAB Revue Centre de documentation En réserve L003 Disponible A first in-flight absolute calibration of the Chilean Earth Observation Satellite / C. Mattar in ISPRS Journal of photogrammetry and remote sensing, vol 92 (June 2014)
[article]
Titre : A first in-flight absolute calibration of the Chilean Earth Observation Satellite Type de document : Article/Communication Auteurs : C. Mattar, Auteur ; J. Hernandez, Auteur ; A. Santamaría-Artigas, Auteur ; M. Inzunza, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 16 - 25 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] capteur en peigne
[Termes IGN] capteur imageur
[Termes IGN] Chili
[Termes IGN] étalonnage de capteur (imagerie)
[Termes IGN] satellite d'observation de la Terre
[Termes IGN] simulation de signalRésumé : (Auteur) This work describes the first in-flight absolute calibration of the “Sistema Satelital para la Observación de la Tierra” (SSOT or Fasat-C). It was performed on January 29th 2013 at Antumapu site located in the southern area of Santiago, Chile. A description of the procedure is presented which includes both ground measurement and atmospheric characterization. The Chilean satellite for Earth observation carries on board a “New AstroSat Optical Modular Instrument” (NAOMI) high-resolution pushbroom imager which provides a 1.45 m ground sampling distance in the panchromatic (0.455–0.744 m) channel and a 5.8 m ground sampling distance for the green (0.455–0.52 m), blue (0.528–0.588 m), red (0.625–0.695 m) and near-infrared (0.758–0.881 m) channels from a 620 km orbit. Radiometric calibration was carried out in order to estimate the land leaving radiance and bidirectional reflectance at the top of the atmosphere. To correct the reflectance data for atmospheric effects, the Second Simulation of a Satellite Signal in the Solar Spectrum (6S) code was used. Aerosol Optical Depth (AOD), water vapor and ozone content were obtained from MOD04, MOD05 and MOD07 products respectively, which are derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data. Statistical results such as BIAS, SIGMA and RMSE were calculated for the comparison between surface reflectance values and in situ measurements. Results show that the overall accuracy of the atmospherically corrected surface reflectance calculated from Fasat-C imagery can be estimated to around +5%, with a R2 coefficient of 0.939 between atmospherically corrected reflectance values and in situ measurements. The atmospheric correction applied in this work by combining MODIS data and the 6S radiative transfer code could be used for further calibration of the Fasat-C images, although in situ atmospheric irradiance measurements are necessary to estimate reliable values of surface reflectance. Future validation tasks have been considered for further applications to natural resources management and surface land cover classification. Numéro de notice : A2014-288 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2014.02.017 En ligne : https://doi.org/10.1016/j.isprsjprs.2014.02.017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33191
in ISPRS Journal of photogrammetry and remote sensing > vol 92 (June 2014) . - pp 16 - 25[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2014061 RAB Revue Centre de documentation En réserve L003 Disponible Registration and visualisation of deformation maps from terrestrial radar interferometry using photogrammetry and structure from motion / Rafael Caduff in Photogrammetric record, vol 29 n° 146 (June - August 2014)PermalinkAutomated geometric correction of multispectral images from high resolution CCD Camera (HRCC) on-board CBERS-2 and CBERS-2B / Chabitha Devarj in ISPRS Journal of photogrammetry and remote sensing, vol 89 (March 2014)PermalinkSpatial and spectral image fusion using sparse matrix factorization / Bo Huang in IEEE Transactions on geoscience and remote sensing, vol 52 n° 3 (March 2014)PermalinkTrends in the optical commercial remote sensing industry (part 1) / Kumar Navulu in GEO: Geoconnexion international, vol 13 n° 3 (march 2014)PermalinkUn vaste champ d'applications / Françoise de Blomac in DécryptaGéo le mag, n° 155 (01/03/2014)PermalinkAn automatic parameter selection procedure for pushbroom sensor models on imaging satellites / Inseong Jeong in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 2 (February 2014)PermalinkAssessing the performance of two unsupervised dimensionality reduction techniques on hyperspectral APEX data for high resolution urban land-cover mapping / Luca Demarchi in ISPRS Journal of photogrammetry and remote sensing, vol 87 (January 2014)PermalinkAtmospheric water vapour sensing by means of differential absorption spectrometry using solar and lunar radiation / Stefan Walter Münch (2014)PermalinkBathymétrie en l’absence de signal GPS : application aux canaux urbains et aux tunnels canaux / Bastien Champier (2014)PermalinkElaboration du référentiel hydrographique d’Haïti à partir d'un MNT ASTER / Laurent Polidori in Revue Française de Photogrammétrie et de Télédétection, n° 205 (Janvier 2014)Permalink