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Gaussian processes uncertainty estimates in experimental Sentinel-2 LAI and leaf chlorophyll content retrieval / Jochem Verrlest in ISPRS Journal of photogrammetry and remote sensing, vol 86 (December 2013)
[article]
Titre : Gaussian processes uncertainty estimates in experimental Sentinel-2 LAI and leaf chlorophyll content retrieval Type de document : Article/Communication Auteurs : Jochem Verrlest, Auteur ; Juan Pablo Rivera, Auteur ; José Moreno, Auteur ; Gustavo Camps-Valls, Auteur Année de publication : 2013 Article en page(s) : pp 157 - 167 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] algorithme de Gauss
[Termes IGN] apprentissage automatique
[Termes IGN] chlorophylle
[Termes IGN] image Sentinel-MSI
[Termes IGN] incertitude des données
[Termes IGN] indice foliaire
[Termes IGN] Leaf Area Index
[Termes IGN] régression
[Termes IGN] surveillance de la végétation
[Termes IGN] teneur en chlorophylle des feuilles
[Termes IGN] variable biophysique (végétation)Résumé : (Auteur) ESA’s upcoming Sentinel-2 (S2) Multispectral Instrument (MSI) foresees to provide continuity to land monitoring services by relying on optical payload with visible, near infrared and shortwave infrared sensors with high spectral, spatial and temporal resolution. This unprecedented data availability leads to an urgent need for developing robust and accurate retrieval methods, which ideally should provide uncertainty intervals for the predictions. Statistical learning regression algorithms are powerful candidats for the estimation of biophysical parameters from satellite reflectance measurements because of their ability to perform adaptive, nonlinear data fitting. In this paper, we focus on a new emerging technique in the field of Bayesian nonparametric modeling. We exploit Gaussian process regression (GPR) for retrieval, which is an accurate method that also provides uncertainty intervals along with the mean estimates. This distinct feature is not shared by other machine learning approaches. In view of implementing the regressor into operational monitoring applications, here the portability of locally trained GPR models was evaluated. Experimental data came from the ESA-led field campaign SPARC (Barrax, Spain). For various simulated S2 configurations (S2-10m, S2-20m and S2-60m) two important biophysical parameters were estimated: leaf chlorophyll content (LCC) and leaf area index (LAI). Local evaluation of an extended training dataset with more variation over bare soil sites led to improved LCC and LAI mapping with reduced uncertainties. GPR reached the 10% precision required by end users, with for LCC a NRMSE of 3.5–9.2% (r2: 0.95–0.99) and for LAI a NRMSE of 6.5–7.3% (r2: 0.95–0.96). The developed GPR models were subsequently applied to simulated Sentinel images over various sites. The associated uncertainty maps proved to be a good indicator for evaluating the robustness of the retrieval performance. The generally low uncertainty intervals over vegetated surfaces suggest that the locally trained GPR models are portable to other sites and conditions. Numéro de notice : A2013-708 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.09.012 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.09.012 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32844
in ISPRS Journal of photogrammetry and remote sensing > vol 86 (December 2013) . - pp 157 - 167[article]Active learning methods for biophysical parameter estimation / Edoardo Pasolli in IEEE Transactions on geoscience and remote sensing, vol 50 n° 10 Tome 2 (October 2012)
[article]
Titre : Active learning methods for biophysical parameter estimation Type de document : Article/Communication Auteurs : Edoardo Pasolli, Auteur ; F. Melgani, Auteur ; N. Alajlan, Auteur ; B. Yakoub, Auteur Année de publication : 2012 Article en page(s) : pp 4071 - 4084 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Intelligence artificielle
[Termes IGN] algorithme de Gauss
[Termes IGN] apprentissage automatique
[Termes IGN] chlorophylle
[Termes IGN] régression
[Termes IGN] séparateur à vaste marge
[Termes IGN] variable biophysique (végétation)Résumé : (Auteur) In this paper, we face the problem of collecting training samples for regression problems under an active learning perspective. In particular, we propose various active learning strategies specifically developed for regression approaches based on Gaussian processes (GPs) and support vector machines (SVMs). For GP regression, the first two strategies are based on the idea of adding samples that are dissimilar from the current training samples in terms of covariance measure, while the third one uses a pool of regressors in order to select the samples with the greater disagreements between the different regressors. Finally, the last strategy exploits an intrinsic GP regression outcome to pick up the most difficult and hence interesting samples to label. For SVM regression, the method based on the pool of regressors and two additional strategies based on the selection of the samples distant from the current support vectors in the kernel-induced feature space are proposed. The experimental results obtained on simulated and real data sets show that the proposed strategies exhibit a good capability to select samples that are significant for the regression process, thus opening the way to the active learning approach for remote-sensing regression problems. Numéro de notice : A2012-528 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2012.2187906 Date de publication en ligne : 17/04/2012 En ligne : https://doi.org/10.1109/TGRS.2012.2187906 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31974
in IEEE Transactions on geoscience and remote sensing > vol 50 n° 10 Tome 2 (October 2012) . - pp 4071 - 4084[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 065-2012101B MANQUANT Revue Centre de documentation Indéterminé Disponible Landscape controls over major nutrients and primary productivity of Arctic lakes / P. Pathak in Cartography and Geographic Information Science, vol 39 n° 4 (October 2012)
[article]
Titre : Landscape controls over major nutrients and primary productivity of Arctic lakes Type de document : Article/Communication Auteurs : P. Pathak, Auteur ; R. Stine, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 187 - 198 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Alaska (Etats-Unis)
[Termes IGN] Arctique
[Termes IGN] azote
[Termes IGN] bassin hydrographique
[Termes IGN] chlorophylle
[Termes IGN] image radar
[Termes IGN] image SPOT
[Termes IGN] interaction spatiale
[Termes IGN] lac
[Termes IGN] macrophyte
[Termes IGN] marais
[Termes IGN] occupation du sol
[Termes IGN] phosphore
[Termes IGN] plante ripicole
[Termes IGN] production primaire brute
[Termes IGN] surveillance
[Termes IGN] zone tamponRésumé : (Auteur) Increasing surface temperatures in the Arctic are affecting the dynamics between lakes and their landscapes. In this paper, we use landscape metrics for land cover and statistical analysis to explore the interactions between such measures as shape and patch density indices for land cover and lake primary productivity. The objective was to identify metrics that could be used to predict lake primary productivity, as measured by chlorophyll a, total nitrogen and total phosphorus estimates. Land cover and landscape metrics for the Toolik region of Alaska were derived using satellite imagery and Fragstats software. The metrics, treated as independent variables in a stepwise regression, were derived for two levels of land cover. The first comprised the entire watershed studied; the second was derived using buffers created around water channels within each watershed. A statistically significant model for each dependent variable was obtained. Results suggest that, of the metrics tested; those related to broad leaf vegetation complexes were most useful in predicting lake primary productivity. The Landscape Shape Index for riparian patches and the Patch Density for heath complex were the two most important metrics for predicting variation in chlorophyll a (p Numéro de notice : A2012-574 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1559/15230406394187 En ligne : https://doi.org/10.1559/15230406394187 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32020
in Cartography and Geographic Information Science > vol 39 n° 4 (October 2012) . - pp 187 - 198[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 032-2012041 RAB Revue Centre de documentation En réserve L003 Disponible Vegetation relevés and soil measurements in the Netherlands: the Ecological Conditions Database (EC) / G.W. Wieger Wamelink in Biodiversity & Ecology, vol 4 (September 2012)
[article]
Titre : Vegetation relevés and soil measurements in the Netherlands: the Ecological Conditions Database (EC) Type de document : Article/Communication Auteurs : G.W. Wieger Wamelink, Auteur ; Marjolein H.C. van Adrichem, Auteur ; Han F. van Dobben, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 125 - 132 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation
[Termes IGN] base de données thématiques
[Termes IGN] facteur édaphique
[Termes IGN] nutriment végétal
[Termes IGN] Pays-Bas
[Termes IGN] relevé
[Termes IGN] vingtième siècleRésumé : (auteur) Since its establishment around 1990, the Ecological Conditions Database (EC; GIVD ID EU-00-006) has been accumulating vegetation relevés from the Netherlands, each accompanied by at least one abiotic soil measurement (e.g. pH or nutrient availability). On 1-1-2010, the database contained 8,229 relevés, covering the period from 1936 to 2009, and representing contributions from 110 authors. The most frequently measured soil parameter is pH, with well over 5,000 entries. All the data in the database are subjected to ISO 9001 quality control. The database can be used as the starting point for estimating plant species responses to a range of abiotic variables, such as pH, groundwater table, or nitrate concentration, and for vegetation modelling (model parameterisation and validation). Numéro de notice : A2012-724 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.7809/b-e.00067 En ligne : http://doi.org/10.7809/b-e.00067 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=87020
in Biodiversity & Ecology > vol 4 (September 2012) . - pp 125 - 132[article]Diameter and death of whorl and interwhorl branches in Atlas cedar (Cedrus atlantica Manetti): a model accounting for acrotony / François Courbet in Annals of Forest Science, Vol 69 n° 2 (March 2012)
[article]
Titre : Diameter and death of whorl and interwhorl branches in Atlas cedar (Cedrus atlantica Manetti): a model accounting for acrotony Type de document : Article/Communication Auteurs : François Courbet, Auteur ; Jean-Christophe Hervé (1961-2017) , Auteur ; Etienne K. Klein, Auteur ; Francis Colin, Auteur Année de publication : 2012 Article en page(s) : pp 125 - 138 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation
[Termes IGN] branche (arbre)
[Termes IGN] Cedrus atlantica
[Termes IGN] diamètre des arbres
[Termes IGN] houppier
[Termes IGN] modèle non linéaire
[Termes IGN] modèle numérique
[Termes IGN] nutrition végétaleRésumé : (auteur) Branch size and branch status (dead or alive) are important characteristics closely related to tree growth and wood quality. The aim of this study was to design models for the diameter and status of branches in Atlas cedar (Cedrus atlantica Manetti). The models were developed from data collected on a set of 32 trees with a wide range of heights (from 3 to 36 m), girths (from 13 to 226 cm), and ages (from 20 to 95 years). A single general segmented model was designed for both whorl and interwhorl branch diameter, taking into account the tree and annual growth unit random effects. The model’s “potential x reducer” form describes the maximum branch diameter profile along the tree and the acrotonic gradient observed in annual shoots. The diameter and status of every branch were modeled based on the vertical position on the trunk and on the height of the base of the living crown. The tree diameter and the branch diameter were used as additional explanatory variables in the branch diameter model and the branch status model, respectively. The model structure is sufficiently general to be suited after re-parameterization for many coniferous species with interwhorl branches such as Spruces, Firs, and Larches. Numéro de notice : A2012-718 Affiliation des auteurs : IFN+Ext (1958-2011) Thématique : FORET Nature : Article DOI : 10.1007/s13595-011-0156-1 Date de publication en ligne : 06/12/2011 En ligne : http://dx.doi.org/10.1007/s13595-011-0156-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83725
in Annals of Forest Science > Vol 69 n° 2 (March 2012) . - pp 125 - 138[article]In situ estimation of water quality parameters in freshwater aquaculture ponds using hyperspectral imaging system / Amr Abd-Elrahman in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 4 (July - August 2011)PermalinkEffect of corn on C-an L-band radar backscatter: a correction method for soil moisture retrieval / A. Joseph in Remote sensing of environment, vol 114 n° 11 (15/11/2010)Permalinkvol 31 n° 17 - 18 - September 2010 - Pan ocean remote sensing : oceanic manifestation of global changes (Bulletin de International Journal of Remote Sensing IJRS) / G. LevyPermalinkHow do trees affect spatio-temporal heterogeneity of nutrient cycling in mediterranean annual grasslands? / Guillermo Gea-Izquierdo in Annals of Forest Science, vol 67 n° 1 (January-February 2010)PermalinkIntegration of water transport pathways in a maple tree: responses of sap flow to branch severing / Nadezhda Nadezhdina in Annals of Forest Science, vol 67 n° 1 (January-February 2010)PermalinkFall fertilization of Pinus resinosa seedlings: nutrient uptake, cold hardiness, and morphological development / M. Anisul Islam in Annals of Forest Science, Vol 66 n° 7 (October - November 2009)PermalinkForest floor contribution to phosphorus nutrition: experimental data / Laurent Augusto in Annals of Forest Science, Vol 66 n° 5 (July - August 2009)PermalinkVariations of plant and soil 87Sr/86Sr along the slope of a tropical inselberg / Anne Poszwa in Annals of Forest Science, Vol 66 n° 5 (July - August 2009)PermalinkWildfire changes the spatial pattern of soil nutrient availability in Pinus canariensis forests / Alexandra Rodríguez in Annals of Forest Science, Vol 66 n° 2 (march 2009)PermalinkLeaf water status and stem xylem flux in relation to soil drought in five temperate broad-leaved tree species with contrasting water use strategies / Paul Köcher in Annals of Forest Science, Vol 66 n° 1 (January - February 2009)Permalink