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Termes IGN > télédétection > télédétection électromagnétique > indice de végétation > indice foliaire > Leaf Area Index
Leaf Area IndexSynonyme(s)LAI |
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Neural network estimation of LAI, fAPAR, fCover and LAI*Cab, from top of canopy MERIS reflectance data: principles and validation / Cédric Bacour in Remote sensing of environment, vol 105 n° 4 (30/12/2006)
[article]
Titre : Neural network estimation of LAI, fAPAR, fCover and LAI*Cab, from top of canopy MERIS reflectance data: principles and validation Type de document : Article/Communication Auteurs : Cédric Bacour, Auteur ; F. Baret, Auteur ; D. Beal, Auteur ; M. Weiss, Auteur ; K. Pavageau, Auteur Année de publication : 2006 Article en page(s) : pp 313 - 325 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] analyse comparative
[Termes IGN] canopée
[Termes IGN] chlorophylle
[Termes IGN] classification par réseau neuronal
[Termes IGN] image Envisat-MERIS
[Termes IGN] Leaf Area Index
[Termes IGN] modèle de transfert radiatif
[Termes IGN] réflectance végétaleRésumé : (Auteur) A neural network is developed to operationally estimate biophysical variables over land surfaces from the observations of the ENVISAT-MERIS instrument: the leaf area index (LAI), the fraction of absorbed photosynthetically active radiation (fAPAR), the fraction of vegetation cover (fCover), and the canopy chlorophyll content (LAI*Cab). The neural network requires as input the geometry of observation and the top of canopy reflectances, corrected from the atmospheric effects, in eleven spectral bands. It is trained on a reflectance database made of radiative transfer model simulations. The principles underlying the generation of the database and the design of the network are first presented. The estimated variables are then compared to other existing products, LAI- and fAPAR-MODIS and MGVI-MERIS, and validated against ground measurements performed in the framework of the VALERI project. Results show remarkable consistency of the temporal dynamics between the several products with however some differences in the range of variation. When compared to actual VALERI ground measurements, the proposed algorithm shows the best performances for LAI (RMSE = 0.47) and fAPAR (RMSE = 0.09). Copyright Elsevier Numéro de notice : A2006-562 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2006.07.014 En ligne : https://doi.org/10.1016/j.rse.2006.07.014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28285
in Remote sensing of environment > vol 105 n° 4 (30/12/2006) . - pp 313 - 325[article]Integration of MODIS data into a simple model for the spatial distributed simulation of soil water content and evapotranspiration / Y. Zhang in Remote sensing of environment, vol 104 n° 4 (30/10/2006)
[article]
Titre : Integration of MODIS data into a simple model for the spatial distributed simulation of soil water content and evapotranspiration Type de document : Article/Communication Auteurs : Y. Zhang, Auteur ; M. Wegehenkel, Auteur Année de publication : 2006 Article en page(s) : pp 393 - 408 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Allemagne
[Termes IGN] analyse diachronique
[Termes IGN] évapotranspiration
[Termes IGN] humidité du sol
[Termes IGN] image Terra-MODIS
[Termes IGN] Leaf Area Index
[Termes IGN] réflectance
[Termes IGN] simulationRésumé : (Auteur) A precise simulation of soil water content (SWC) and actual evapotranspiration (ETa) in a region or a catchment depends on the accuracy of the spatial data inputs. In this study, we developed a simple grid-based soil water balance model. In this model, remotely sensed vegetation data are used to estimate spatial distributions of daily SWC and ETa rates. The model was validated by comparing simulated SWC with the measured by gravimetric method and time domain reflectometry (TDR) at an experimental test site located in Northeastern Germany in the time period 1993–1998. The index of agreement IA and the root-mean-square error obtained from the comparison of the TDR measurements to the simulated values ranged from 0.45 to 0.80 and from 0.029 to 0.061 cm3/cm3, respectively. The comparison of simulated ETa rates to those measured by four large-scale lysimeters at another test site showed IA values above 0.87 and R2 values higher than 0.59. For the regional application of the model, a method was developed to integrate the Moderate Resolution Imaging Spectrometer (MODIS) vegetation data into the model. The MODIS data used in our study consist of 16-day normalized difference vegetation index and 8-day leaf area index products. Regarding the spatial application of the model, our approach was tested in a catchment located in Northeastern Germany in 2001–2003. A sufficient correlation between daily discharge rates measured at two observation gauges in the catchment and the corresponding simulated discharge rates and also good correlations between the simulated ETa rates and the MODIS-leaf area index values indicate that the model is an appropriate simulation tool at regional scale if the corresponding additional spatial databases regarding surface and soil properties are available. Copyright Elsevier Numéro de notice : A2006-496 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2006.05.011 En ligne : https://doi.org/10.1016/j.rse.2006.05.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28220
in Remote sensing of environment > vol 104 n° 4 (30/10/2006) . - pp 393 - 408[article]LAI retrieval from multiangular image classification and inversion of a ray tracing model / R. Casa in Remote sensing of environment, vol 98 n° 4 (30/10/2005)
[article]
Titre : LAI retrieval from multiangular image classification and inversion of a ray tracing model Type de document : Article/Communication Auteurs : R. Casa, Auteur ; H.G. Jones, Auteur Année de publication : 2005 Article en page(s) : pp 414 - 428 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] classification dirigée
[Termes IGN] couvert végétal
[Termes IGN] cultures
[Termes IGN] image multiangulaire
[Termes IGN] Italie
[Termes IGN] lancer de rayons
[Termes IGN] Leaf Area Index
[Termes IGN] modèle d'inversion
[Termes IGN] modèle de diffusion du rayonnement
[Termes IGN] pomme de terre
[Termes IGN] rayonnement infrarouge
[Termes IGN] réflectance végétaleRésumé : (Auteur) A non-conventional approach for the estimation of leaf area index (LAI) and leaf angle distribution (LAD), based on the use of information contained in multiangular images and the inversion of a canopy ray tracing model, is proposed in this work. As an alternative to the use of overall image reflectance data, the image fraction components, i.e. sunlit and shaded leaves and soil, are obtained by supervised classification of groundbased multiangular images acquired using an inexpensive colour infrared camera, the Dycam ADC. These data are used for the inversion of a numerical model of a vegetation canopy in which the latter is described as composed of randomly distributed disks (leaves). The model was developed using the POV-ray ray tracer. Model inversion is carried out using the look-up-table approach. The proposed methodology was tested using an extensive data set gathered on the potato crop during experimental trials carried out at Viterbo (Italy) for 3 years. The results show that LAI was successfully estimated with a RMSE varying from 0.29 to 0.75 in the different years. The potential sources of error in both estimated and measured LAI values are extensively discussed. Numéro de notice : A2005-433 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2005.08.005 En ligne : https://doi.org/10.1016/j.rse.2005.08.005 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27569
in Remote sensing of environment > vol 98 n° 4 (30/10/2005) . - pp 414 - 428[article]Estimating live fuel moisture content from remotely sensed reflectance / F. Mark Danson in Remote sensing of environment, vol 92 n° 3 (30 August 2004)
[article]
Titre : Estimating live fuel moisture content from remotely sensed reflectance Type de document : Article/Communication Auteurs : F. Mark Danson, Auteur ; P. Bowyer, Auteur Année de publication : 2004 Article en page(s) : pp 309 - 321 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] combustible
[Termes IGN] humidité de l'air
[Termes IGN] incendie de forêt
[Termes IGN] indice de végétation
[Termes IGN] Leaf Area Index
[Termes IGN] réflectance spectrale
[Termes IGN] réflectance végétale
[Termes IGN] risque naturel
[Termes IGN] teneur en eau de la végétationRésumé : (Auteur) Fuel moisture content (FMC) is used in forest fire danger models to characterise the moisture status of the foliage. FMC expresses the amount of water in a leaf relative to the amount of dry matter and differs from measures of leaf water content which express the amount of water in a leaf relative to its area. FMC is related to both leaf water content and leaf dry matter content, and the relationships between FMC and remotely sensed reflectance will therefore be affected by variation in both leaf biophysical properties. This paper uses spectral reflectance data from the Leaf Optical Properties EXperiment (LOPEX) and modelled data from the Prospect leaf reflectance model to examine the relationships between FMC, leaf equivalent water thickness (EWT) and a range of spectral vegetation indices (VI) designed to estimate leaf and canopy water content. Significant correlations were found between FMC and all of the selected vegetation indices for both modelled and measured data, but statistically stronger relationships were found with leaf EWT; overall, the water index (WI) was found to be most strongly correlated with FMC. The accuracy of FMC estimation was very low when the global range of FMC was examined, but for a restricted range of 0- 100%, FMC was estimated with a root-mean-square error (RMSE) of 15% in the model simulations and 51% with the measured data. The paper shows that the estimation of live FMC from remotely sensed vegetation indices is likely to be problematic when there is variability in both leaf water content and leaf dry matter content in the target leaves. Estimating FMC from remotely sensed data at the canopy level is likely to be further complicated by spatial and temporal variations in leaf area index (LAI). Further research is required to assess the potential of canopy reflectance model inversion to estimate live fuel moisture content where a priori information on vegetation properties may be used to constrain the inversion process. Numéro de notice : A2004-383 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.03.017 En ligne : https://doi.org/10.1016/j.rse.2004.03.017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26910
in Remote sensing of environment > vol 92 n° 3 (30 August 2004) . - pp 309 - 321[article]Leaf Area Index measurements in a tropical moist forest: a case study from Costa Rica / M. Kalacska in Remote sensing of environment, vol 91 n° 2 (30/05/2004)
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Titre : Leaf Area Index measurements in a tropical moist forest: a case study from Costa Rica Type de document : Article/Communication Auteurs : M. Kalacska, Auteur ; G.A. Sanchez-Azofeifa, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 134 - 152 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] canopée
[Termes IGN] Costa Rica
[Termes IGN] forêt tropicale
[Termes IGN] indice de végétation
[Termes IGN] Leaf Area Index
[Termes IGN] méthode des moindres carrés
[Termes IGN] régression linéaireRésumé : (Auteur) The role of tropical forests in sustainable development mechanisms and payments for environmental services is becoming increasingly important. Therefore, there is a greater need for accurate and detailed information about their biophysical characteristics (e.g., Leaf area index-LAI) along different stages of ecological succession. Remote sensing offers the possibility of providing relatively accurate estimations of such biophysical characteristics at a reasonable cost for most regional projects. The objectives of this study are to (1) document the variability of LAI in different stages of secondary growth in a tropical moist forest, (2) estimate LAI from spectral vegetation indices (SVIs), and (3) link LAI to the estimation of other canopy physiognomic characteristics. We found that segregation of LAI measurements by successional stage (early, intermediate, late) contributed to a better definition of the relationship between LAI and the SVIs. In addition, we conclude that the propagation of errors of precision through the SVI formulas must be taken into consideration along with intra-site and radiometric variability when uncertainty terms are calculated. From a linear regression analysis, we found that there is only a minimal difference between the nonparametric Theil-Sen and classical least-squares regressions. We also found that not only does the Lorentzian cumulative transition function describe the relationship between LAI and the SVIs, it also provides an estimate of the range of LAI values to which each index is sensitive. Numéro de notice : A2004-241 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.02.011 En ligne : https://doi.org/10.1016/j.rse.2004.02.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26768
in Remote sensing of environment > vol 91 n° 2 (30/05/2004) . - pp 134 - 152[article]Wavelet transform applied to EO-1 hyperspectral data for forest LAI and crown closure mapping / R. Pu in Remote sensing of environment, vol 91 n° 2 (30/05/2004)PermalinkEvaluation of the MODIS LAI at coniferous forest site in Finland / Y. Wang in Remote sensing of environment, vol 91 n° 1 (15/05/2004)PermalinkUsing Lidar and effective LAI data to evaluate Ikonos and Landsat 7 ETM+ vegetation cover estimates in a ponderosa pine forest / X. Chen in Remote sensing of environment, vol 91 n° 1 (15/05/2004)PermalinkAirborne measurement of hot spot reflectance signatures / F. Camacho-De Coca in Remote sensing of environment, vol 90 n° 1 (15/03/2004)PermalinkComparisons of land cover and LAI estimates derived from ETM+ and MODIS for four sites in North America: a quality assessment of 2000/2001 provisional MODIS / W.B. Cohen in Remote sensing of environment, vol 88 n° 3 (15/12/2003)PermalinkTraining a neural network with a canopy reflectance model to estimate crop leaf area index / F. Mark Danson in International Journal of Remote Sensing IJRS, vol 24 n° 23 (December 2003)PermalinkSchätzung von Vegetationsparametern aus multispektralen Fernerkundungsdaten / F. Kurz (2003)PermalinkEvaluation of narrowband and broadband vegetation indices for determining optimal hyperspectral wavebands for agricultural crop characterization / Prasad S. Thenkabail in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 6 (June 2002)PermalinkInversion du modèle de transfert radiatif DART [discrete anisotropic radiative transfer] / P. Esteve (1998)PermalinkApport de la modélisation du transfert radiatif pour l'étude des écosystèmes forestiers par télédétection / V. Pinel (1997)Permalink