Centre de documentation
scientifique

Angular reflectance of leaves with a dual-wavelength terrestrial lidar and its implications for leaf-bark separation and leaf moisture estimation / Steven Hancock in IEEE Transactions on geoscience and remote sensing, vol 55 n° 6 (June 2017)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 55 n° 6 (June 2017) . - pp 3084 - 3090 Titre : Angular reflectance of leaves with a dual-wavelength terrestrial lidar and its implications for leaf-bark separation and leaf moisture estimation Type de document : Article/Communication Auteurs : Steven Hancock, Auteur ; Rachel Gaulton, Auteur ; F. Mark Danson, Auteur Année de publication : 2017 Article en page(s) : pp 3084 - 3090 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] angle d'incidence [Termes IGN] données lidar [Termes IGN] écorce [Termes IGN] indice de diversité [Termes IGN] longueur d'onde [Termes IGN] réflectance de surface [Termes IGN] réflectance végétale [Termes IGN] teneur en eau de la végétation Résumé : (Auteur) A new generation of multiwavelength lidars offers the potential to measure the structure and biochemistry of vegetation simultaneously, using range resolved spectral indices to overcome the confounding effects in passive optical measurements. However, the reflectance of leaves depends on the angle of incidence, and if this dependence varies between wavelengths, the resulting spectral indices will also vary with the angle of incidence, complicating their use in separating structural and biochemical effects in vegetation canopies. The Salford Advanced Laser Canopy Analyser (SALCA) dual-wavelength terrestrial laser scanner was used to measure the angular dependence of reflectance for a range of leaves at the wavelengths used by the new generation of multiwavelength lidars, 1063 and 1545 nm, as used by SALCA, DWEL, and the Optech Titan. The influence of the angle of incidence on the normalized difference index (NDI) of these wavelengths was also assessed. The reflectance at both wavelengths depended on the angle of incidence and could be well modelled as a cosine. The change in the NDI with the leaf angle of incidence was small compared with the observed difference in the NDI between fresh and dry leaves and between leaf and bark. Therefore, it is concluded that angular effects will not significantly impact leaf moisture retrievals or prevent leaf/bark separation for the wavelengths used in the new generation of 1063- and 1545-nm multiwavelength lidars. Numéro de notice : A2017-474 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2652140 En ligne : http://dx.doi.org/10.1109/TGRS.2017.2652140 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86399 [article]

Lidar mapping of canopy gaps in continuous cover forests : a comparison of canopy height model and point cloud based techniques / Rachel Gaulton in International Journal of Remote Sensing IJRS, vol 31 n° 5 (March 2010)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 31 n° 5 (March 2010) . - pp 1193 - 1211 Titre : Lidar mapping of canopy gaps in continuous cover forests : a comparison of canopy height model and point cloud based techniques Type de document : Article/Communication Auteurs : Rachel Gaulton, Auteur ; T.J. Malthus, Auteur Année de publication : 2010 Conférence : Silvilaser 2008, 8th international conference on Lidar applications in forest assessment and inventory 17/09/2008 19/09/2008 Edimbourg Royaume-Uni Proceedings Taylor&Francis Article en page(s) : pp 1193 - 1211 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] canopée [Termes IGN] couvert forestier [Termes IGN] données lidar [Termes IGN] hauteur des arbres [Termes IGN] semis de points [Termes IGN] surveillance forestière [Termes IGN] système d'information géographique Résumé : (Auteur) In continuous cover forest systems, canopy gaps are created by management activities with an aim of encouraging natural regeneration and of increasing structural heterogeneity. Light Detection and Ranging (LiDAR) may provide a more accurate means to assess gap distribution than ground survey, allowing more effective monitoring. This paper presents a new approach to gap delineation, based on identifying gaps directly from the point cloud and avoiding the need for interpolation of returns to a canopy height model (CHM). Areas of canopy are identified through local maxima identification, filtering and clustering of the point cloud, with gaps subsequently delineated in a GIS environment. When compared to field surveyed gap outlines, the algorithm has an overall accuracy of 88% for data with a high LiDAR point density (11.4 returns per m2) and accuracy of up to 77% for lower density data (1.2 returns per m2). The method provides an increase in overall and Producer's accuracy of 4 and 8% respectively, over a method based on the use of a CHM. The estimation of total gap area is improved by, on average, 16% over the CHM based approach. Results indicate that LiDAR data can be used accurately to delineate gaps in managed forests, potentially allowing more accurate and spatially explicit modelling of understorey light conditions. Copyright Taylor & Francis Numéro de notice : A2010-251 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160903380565 En ligne : https://doi.org/10.1080/01431160903380565 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30445 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-2010031	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt