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Comparison of spectral indices obtained using multiple spectroradiometers / K.L. Castro-Esau in Remote sensing of environment, vol 103 n° 3 (15 August 2006)  

Public [article]  inRemote sensing of environment > vol 103 n° 3 (15 August 2006) . - pp 276 - 288 Titre : Comparison of spectral indices obtained using multiple spectroradiometers Type de document : Article/Communication Auteurs : K.L. Castro-Esau, Auteur ; G.A. Sanchez-Azofeifa, Auteur ; B. Rivard, Auteur Année de publication : 2006 Article en page(s) : pp 276 - 288 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] analyse comparative [Termes IGN] éclairement lumineux [Termes IGN] indice de végétation [Termes IGN] réflectance spectrale [Termes IGN] réflectance végétale [Termes IGN] spectromètre imageur Résumé : (Auteur) To determine the degree of comparability between three spectrometers (Analytical Spectral Devices FieldSpec Pro FR (FR), Analytical Spectral Devices HandHeld (HH), and UniSpec Spectral Analysis System (UN)), leaf spectra of three species (Cafea arabica, Lantana camara, Eriobotrya japonica), recorded from each instrument, were compared using two illumination, viewing, and field of view (FOV) scenarios. Scenario 1 eliminated differences due to illumination, viewing, and FOV conditions. Scenario 2 represented a ‘typical’ illumination and viewing set-up for each instrument. Six vegetation indices were computed from the raw spectra as well as spectra (1) interpolated to 1-nm intervals (the sampling interval of the FR) and (2) interpolated to 3.3 nm (the sampling interval of the UN). The spectra measured from the three instruments differed in both shape and amplitude, more so for scenario 2 than scenario 1. In many cases, indices obtained using one instrument differed significantly from the same indices obtained using the other two instruments (but the same leaves), regardless of scenario. The severity of these differences varied between indices. Interpolation was generally ineffective in ‘matching’ the spectra from the various instruments. Care should be exercised when comparing indices generated from spectra measured from different instruments. Copyright Elsevier Numéro de notice : A2006-332 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2005.01.019 En ligne : https://doi.org/10.1016/j.rse.2005.01.019 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28056 [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)  

Public [article]  inRemote sensing of environment > vol 91 n° 2 (30/05/2004) . - pp 134 - 152 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 linéaire Résumé : (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 [article]