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Integrating imaging spectroscopy and neural networks to map grass quality in the Kruger National Park, South Africa / Onisimo Mutanga in Remote sensing of environment, vol 90 n° 1 (15/03/2004)
[article]
Titre : Integrating imaging spectroscopy and neural networks to map grass quality in the Kruger National Park, South Africa Type de document : Article/Communication Auteurs : Onisimo Mutanga, Auteur ; Andrew K. Skidmore, Auteur Année de publication : 2004 Article en page(s) : pp 104 - 115 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Afrique du sud (état)
[Termes IGN] analyse comparative
[Termes IGN] azote
[Termes IGN] bande infrarouge
[Termes IGN] bande visible
[Termes IGN] erreur moyenne quadratique
[Termes IGN] herbe
[Termes IGN] image aérienne
[Termes IGN] image HYMAP
[Termes IGN] image hyperspectrale
[Termes IGN] régression linéaire
[Termes IGN] régression multiple
[Termes IGN] réseau neuronal artificiel
[Termes IGN] savaneRésumé : (Auteur) A new integrated approach, involving continuum-removed absorption features, the red edge position and neural networks, is developed and applied to map grass nitrogen concentration in an African savanna rangeland. Nitrogen, which largely determines the nutritional quality of grasslands, is commonly the most limiting nutrient for grazers. Therefore, the remote sensing of foliar nitrogen concentration in savanna rangelands is important for an improved understanding of the distribution and feeding patterns of wildlife. Continuum removal was applied on two absorption features located in the visible (R 550-757) and the SWIR (R 2015-2199) from an atmospherically corrected HYMAP MK1 image. A feature selection algorithm was used to select wavelength variables from the absorption features. Selected band depths from the absorption features as well as the red edge position (REP) were input into a backpropagation neural network. The best-trained neural network was used to map nitrogen concentration over the whole study area. Results indicate that the new integrated approach could explain 60% of the variation in savanna grass nitrogen concentration on an independent test data set, with a root mean square error (rmse) of 0. 13 (+ 8.3 0% of the mean observed nitrogen concentration). This result is better compared to the result obtained using multiple linear regression, which yielded an R of 38%, with a RMSE of 0.16 (+ 10.30% of the mean observed nitrogen concentration) on an independent test data set. The study demonstrates the potential of airborne hyperspectral data and neural networks to estimate and ultimately to map nitrogen concentration in the mixed species environments of Southern Africa. Numéro de notice : A2004-130 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.12.004 En ligne : https://doi.org/10.1016/j.rse.2003.12.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26657
in Remote sensing of environment > vol 90 n° 1 (15/03/2004) . - pp 104 - 115[article]Estimating fragmentation effects on simulated forest net primary productivity derived from satellite imagery / Nicholas C. Coops in International Journal of Remote Sensing IJRS, vol 25 n° 4 (February 2004)
[article]
Titre : Estimating fragmentation effects on simulated forest net primary productivity derived from satellite imagery Type de document : Article/Communication Auteurs : Nicholas C. Coops, Auteur ; J.D. White, Auteur ; N.A. Scott, Auteur Année de publication : 2004 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] canopée
[Termes IGN] carbone
[Termes IGN] écosystème forestier
[Termes IGN] forêt
[Termes IGN] image multibande
[Termes IGN] image SPOT-Végétation
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] Nouvelle-Zélande
[Termes IGN] production primaire netteRésumé : (Auteur) Conversion of native forests to agriculture and urban land leads to fragmentation of forested landscapes with significant consequences for habitat conservation and forest productivity. When quantifying land-cover patterns from airborne or spaceborne sensors, the interconnectedness of fragmented landscapes may vary depending on the spatial resolution of the sensor and the extent at which the landscape is being observed. This scale dependence can significantly affect calculation of remote sensing vegetation indices, such as the Normalized Difference Vegetation Index (NDVI) and its subsequent use to predict biophysical parameters such as the fraction of photosynthetically active radiation intercepted by forest canopies (fPAR). This means that simulated above-ground net primary productivity (NPPA) using canopy radiation interception models such as 3-PG (Physiological Principles for Predicting Growth), coupled with remote sensing observations, can yield different results in fragmented landscapes depending on the spatial resolution of the remotely sensed data. We compared the amount of forest fragmentation in 1 km SPOT-4 VEGETATION pixels using a simultaneously acquired 20m SPOT-4 multispectral (XS) image. We then predicted NPPA for New Zealand native forest ecosystems using the 3-PG model with satellite-derived estimates of the WAR obtained from the SPOT-4 VEGETATION sensor, using NDVI values with and without correction for fragmentation. We examined three methods to correct for sub-pixel fragmentation effects on NPPA. These included: (1) a simple conversion between the broad 1 km scale NDVI values and the XS NDVI values; (2) utilisation of contextural information from XS NDVI pixels to derive a single coefficient to adjust the 1 km NDVI values; and (3) calculation of the degree of fragmentation within each VEGETATION 1 km pixel and reduce NDVI by an empirically derived amount based on the proportional areal coverage of forest in each pixel. Our results indicate that predicted NPPA derived from uncorrected 1 km VEGETATION pixels was significantly higher than estimates using adjusted NDVI values; all three methods reduced the predicted NPPA. In areas of the landscape with a large degree of forest defragmentation (such as forest boundaries) predictions of NPPa indicate that the fragmentation effect has implications for spatially extensive estimates of carbon uptake by forests. Numéro de notice : A2004-076 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000115094 En ligne : https://doi.org/10.1080/0143116031000115094 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26604
in International Journal of Remote Sensing IJRS > vol 25 n° 4 (February 2004)[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-04041 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Predicting in situ pasture quality in the Kruger National Park, South Africa, using continuum-removed absorption features / Onisimo Mutanga in Remote sensing of environment, vol 89 n° 3 (15/02/2004)
[article]
Titre : Predicting in situ pasture quality in the Kruger National Park, South Africa, using continuum-removed absorption features Type de document : Article/Communication Auteurs : Onisimo Mutanga, Auteur ; Andrew K. Skidmore, Auteur ; Herbert H.T. Prins, Auteur Année de publication : 2004 Article en page(s) : pp 393 - 408 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] Afrique du sud (état)
[Termes IGN] azote
[Termes IGN] biochimie
[Termes IGN] carbone
[Termes IGN] forêt tropicale
[Termes IGN] image hyperspectrale
[Termes IGN] parc naturel national
[Termes IGN] paturage
[Termes IGN] phosphore
[Termes IGN] potassium
[Termes IGN] prairie
[Termes IGN] réflectance végétale
[Termes IGN] régression linéaire
[Termes IGN] savane
[Termes IGN] spectroradiomètre
[Termes IGN] zone intertropicaleRésumé : (Auteur) The remote sensing of pasture quality as determined by nitrogen, phosphorous, potassium, calcium and magnesium concentration is critical for a better understanding of wildlife and livestock feeding patterns. Although remote sensing techniques have proved useful for assessing the concentration of foliar biochemicals under controlled laboratory conditions, more investigation is required to assess their capabilities in the field where inconsistent results have been obtained so far. We investigated the possibility of determining the concentration of in situ biochemicals in a savanna rangeland, using the spectral reflectance of five grass species. Canopy spectral measurements were taken in the field using a GER 3700 spectroradiometer. We tested the utility of using four variables derived from continuum-removed absorption features for predicting canopy nitrogen, phosphorous, potassium, calcium and magnesium concentration: (i) continuum-removed derivative reflectance (CRDR), (ii) band depth (BD), (iii) band depth ratio (BDR) and (iv) normalised band depth index (NBDI). Stepwise linear regression was used to select wavelengths from the absorption-feature-based variables. Univariate correlation analysis was also done between the first derivative reflectance and biochemicals. Using a training data set, the variables derived from continuum-removed absorption features could predict biochemicals with R2 values ranging from 0.43 to 0.80. Results were highest using CRDR data, which yielded R2 values of 0.70, 0.80, 0.64, 0.50 and 0.68 with root mean square errors (RMSE) of 0.01, 0.004, 0.03, 0.01 and 0.004 for nitrogen, phosphorous, potassium, calcium and magnesium, respectively. Predicting biochemicals on a test data set, using regression models developed from a training data set. resulted in R2 values ranging from 0. 15 to 0.70. The error of prediction (RSE) in the test data set was 0.08 (+ 10.25% of mean), 0.05 (+ 5.2% of mean), 0.02 (+ 11.11% of mean), 0.05 (+ 11.6% of mean) and 0.03 (+ 15% of mean) for nitrogen, potassium, phosphorous. calcium and magnesium, respectively, using CRDR. When data was partitioned into species groups, the R2 increased significantly to >0.80. With high-quality radiometric and geometric calibration of hyperspectral imagery, the techniques applied in this study (i.e. continuum removal on absorption features) may also be applied on data acquired by airborne and spacebome imaging spectrometers to predict and ultimateIy to map the concentration of macronutrients in tropical rangelands. Numéro de notice : A2004-020 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2003.11.001 En ligne : https://doi.org/10.1016/j.rse.2003.11.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26548
in Remote sensing of environment > vol 89 n° 3 (15/02/2004) . - pp 393 - 408[article]Automated subpixel photobathymetry and water quality mapping / R.L. Huguenin in Photogrammetric Engineering & Remote Sensing, PERS, vol 70 n° 1 (January 2004)
[article]
Titre : Automated subpixel photobathymetry and water quality mapping Type de document : Article/Communication Auteurs : R.L. Huguenin, Auteur ; M.H. Wang, Auteur ; R. Biehl, Auteur ; S. Stoodley, Auteur ; J.N. Rogers, Auteur Année de publication : 2004 Article en page(s) : pp 111 - 123 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] bathymétrie
[Termes IGN] carbone
[Termes IGN] carte thématique
[Termes IGN] chlorophylle
[Termes IGN] classification
[Termes IGN] image Ikonos
[Termes IGN] image multibande
[Termes IGN] lac
[Termes IGN] Massachusetts (Etats-Unis)
[Termes IGN] pollution des eaux
[Termes IGN] précision infrapixellaire
[Termes IGN] profondeur
[Termes IGN] qualité des eaux
[Termes IGN] sédiment
[Termes IGN] turbidité océaniqueRésumé : (Auteur) New photobathymetry and water quality software is described here that utilizes subpixel analysis software (Subpixel Classifier) with an autonomous image calibration procedure and analytic retrieval algorithm to simultaneously retrieve and report bottom depth and the concentrations of suspended chlorophyll, suspended sediments, and colored dissolved organic carbon on a perpixel basis from four-band multispectral image data. From the derived composition, the QSC2 (Quantitative Shoreline Characterization, Version 2.0) software also computes and reports water column visibility parameters (vertical and horizontal subsurface sighting ranges and turbidity, each at four wavelength band passes, plus Secchi depth as a scalar) as well as depth and turbidity confidence. Qsc2 compensates for the effects of the atmosphere, sun and sky reflections from the water surface, subpixel contributions from exposed land, and variations in the bottom material properties. All information is derived automatically from the pixel data alone. The performance of the Qsc2 software was demonstrated using a four-band Ikonos image of Plymouth, Massachusetts. Accuracies of the image-derived compositions, water clarity, and depths were assessed using field and laboratory measurements for eight representative lakes in the scene. The means of the differences of the field-measured and image-derived suspended chlorophyll and colored dissolved organic carbon concentrations for the eight lakes were 1.82 ug/l and 4.34 mgC/1, respectively. The image-derived concentrations of suspended sediments were all below the threshold of detection for the field samples (5 mg/1), in agreement with the field data. The mean of the differences between field-measured and image-derived Secchi depths was 0.76 m. The mean depth difference was 0.57 m. Numéro de notice : A2004-005 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.70.1.111 En ligne : https://doi.org/10.14358/PERS.70.1.111 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26533
in Photogrammetric Engineering & Remote Sensing, PERS > vol 70 n° 1 (January 2004) . - pp 111 - 123[article]Sites pollués en France / Frédéric Ogé (2004)
Titre : Sites pollués en France : enquête sur un scandale sanitaire Type de document : Monographie Auteurs : Frédéric Ogé, Auteur ; Pierre Simon, Auteur Editeur : Paris : Librio Année de publication : 2004 Collection : Santé num. 662 Importance : 94 p. Format : 13 x 20 cm ISBN/ISSN/EAN : 978-2-290-34296-1 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Environnement
[Termes IGN] France métropolitaine
[Termes IGN] plomb
[Termes IGN] pollution des sols
[Termes IGN] risque sanitaire
[Termes IGN] risque technologique
[Termes IGN] site polluéRésumé : (Editeur) Le constat est sévère : la France compte plus de 300.000 sites potentiellement pollués. Combien d'écoles, de foyers, de lieux publics sont encore aujourd'hui construits sur des sites contaminés ? Ce guide aide à prendre conscience, pour réagir : Où sont les sites ? Comment savoir si un terrain est sain ? Que faire en cas de doute ? Quelles sont les entreprises polluantes ? Vous trouverez ici une source d'informations précieuse et fiable pour mieux connaître les risques et les recours possibles. L'ouvrage contient aussi 7 cartes de grandes villes françaises, 22 fiches détaillées par région, des conseils de prévention et de protection et des contacts utiles. Numéro de notice : 13252 Affiliation des auteurs : non IGN Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54936 Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 13252-01 50.00 Livre Centre de documentation Environnement Disponible 13252-02 50.00 Livre Centre de documentation Environnement Disponible Analysis of hyperspectral data for estimation of temperate forest canopy nitrogen concentration: Comparison between an Airborne (AVIRIS) and a spaceborne (Hyperion) sensor / M.L. Smith in IEEE Transactions on geoscience and remote sensing, vol 41 n° 6 (June 2003)PermalinkPermalinkEvaluation 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)PermalinkApprofondissement des techniques de diagnostique des propriétés spectrales d'une culture / Laure Chandelier (2002)PermalinkÉlaboration d'un modèle de minéralisation de l'azote du sol / J. Drivon (2002)PermalinkChemistry of the upper and lower atmosphere / B.J. Finlayson-Pitts (2001)PermalinkDiagnostic de territoire et contrats territoriaux d'exploitation / M. Ducau (2001)PermalinkCharacterising the temporal variability of the global carbon cycle / I.G. Enting (1999)PermalinkPurging the past / G. Buttner in GIS Europe, vol 7 n° 6 (01/06/1998)PermalinkContribution à la mise en place d'un outil de cartographie pour réseaux de stations de mesures / V. Puybonnieux-Texier (1996)Permalink