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Modelling forest canopy trends with on-demand spatial simulation / Gordon M. Green in International journal of geographical information science IJGIS, vol 30 n° 1-2 (January - February 2016)
[article]
Titre : Modelling forest canopy trends with on-demand spatial simulation Type de document : Article/Communication Auteurs : Gordon M. Green, Auteur ; Sean C. Ahearn, Auteur Année de publication : 2016 Article en page(s) : pp 61 - 73 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web
[Termes IGN] champ aléatoire de Markov
[Termes IGN] forêt
[Termes IGN] image Terra-MODIS
[Termes IGN] modèle numérique de surface de la canopée
[Termes IGN] service web géographique
[Termes IGN] simulation numériqueRésumé : (auteur) Understanding trends in forest canopy cover at local, national, and global scales is important for many applications, including policymaking related to forest carbon sequestration. Globally consistent land-cover data sets derived from MODerate-resolution Imaging Spectroradiometer (MODIS) are now available for a period of more than 10 years, long enough to detect trends both in deforestation and in afforestation. However, methods of modelling land-cover change normally require specialized software and expertise, limiting the availability of this information. This barrier to access can be eliminated through the use of web services that construct models on demand based on user-specified regions of interest, so that parameters are inferred from, and relevant to, local conditions. In this paper we present a proof-of-concept system for building and running spatial Markov chain models of forest-cover change on demand, and demonstrate how the on-demand approach may be implemented for similar applications. Numéro de notice : A2016-010 Affiliation des auteurs : non IGN Thématique : FORET/GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2015.1066791 En ligne : http://dx.doi.org/10.1080/13658816.2015.1066791 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79331
in International journal of geographical information science IJGIS > vol 30 n° 1-2 (January - February 2016) . - pp 61 - 73[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 079-2016011 RAB Revue Centre de documentation En réserve L003 Disponible Effect of slope on treetop detection using a LiDAR Canopy Height Model / Anahita Khosravipour in ISPRS Journal of photogrammetry and remote sensing, vol 104 (June 2015)
[article]
Titre : Effect of slope on treetop detection using a LiDAR Canopy Height Model Type de document : Article/Communication Auteurs : Anahita Khosravipour, Auteur ; Tiejun Wang, Auteur ; Martin Isenburg, Auteur ; Kourosh Khoshelham, Auteur Année de publication : 2015 Article en page(s) : pp 44 - 52 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] houppier
[Termes IGN] modèle numérique de surface de la canopée
[Termes IGN] pente
[Termes IGN] Pinus mugo subsp. uncinata
[Termes IGN] Pinus sylvestris
[Termes IGN] semis de pointsRésumé : (auteur) Canopy Height Models (CHMs) or normalized Digital Surface Models (nDSM) derived from LiDAR data have been applied to extract relevant forest inventory information. However, generating a CHM by height normalizing the raw LiDAR points is challenging if trees are located on complex terrain. On steep slopes, the raw elevation values located on either the downhill or the uphill part of a tree crown are height-normalized with parts of the digital terrain model that may be much lower or higher than the tree stem base, respectively. In treetop detection, a highest crown return located in the downhill part may prove to be a “false” local maximum that is distant from the true treetop. Based on this observation, we theoretically and experimentally quantify the effect of slope on the accuracy of treetop detection. The theoretical model presented a systematic horizontal displacement of treetops that causes tree height to be systematically displaced as a function of terrain slope and tree crown radius. Interestingly, our experimental results showed that the effect of CHM distortion on treetop displacement depends not only on the steepness of the slope but more importantly on the crown shape, which is species-dependent. The influence of the systematic error was significant for Scots pine, which has an irregular crown pattern and weak apical dominance, but not for mountain pine, which has a narrow conical crown with a distinct apex. Based on our findings, we suggest that in order to minimize the negative effect of steep slopes on the CHM, especially in heterogeneous forest with multiple species or species which change their morphological characteristics as they mature, it is best to use raw elevation values (i.e., use the un-normalized DSM) and compute the height after treetop detection. Numéro de notice : A2015-700 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2015.02.013 En ligne : https://doi.org/10.1016/j.isprsjprs.2015.02.013 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78336
in ISPRS Journal of photogrammetry and remote sensing > vol 104 (June 2015) . - pp 44 - 52[article]Validation of canopy height profile methodology for small-footprint full-waveform airborne LiDAR data in a discontinuous canopy environment / Karolina D. Fieber in ISPRS Journal of photogrammetry and remote sensing, vol 104 (June 2015)
[article]
Titre : Validation of canopy height profile methodology for small-footprint full-waveform airborne LiDAR data in a discontinuous canopy environment Type de document : Article/Communication Auteurs : Karolina D. Fieber, Auteur ; Ian J. Davenport, Auteur ; Mihai A. Tanase, Auteur ; James M. Ferryman, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 144 - 157 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] Australie
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] forme d'onde pleine
[Termes IGN] hauteur des arbres
[Termes IGN] Leaf Area Index
[Termes IGN] modèle numérique de surface de la canopéeRésumé : (auteur) A Canopy Height Profile (CHP) procedure presented in Harding et al. (2001) for large footprint LiDAR data was tested in a closed canopy environment as a way of extracting vertical foliage profiles from LiDAR raw-waveform. In this study, an adaptation of this method to small-footprint data has been shown, tested and validated in an Australian sparse canopy forest at plot- and site-level. Further, the methodology itself has been enhanced by implementing a dataset-adjusted reflectance ratio calculation according to Armston et al. (2013) in the processing chain, and tested against a fixed ratio of 0.5 estimated for the laser wavelength of 1550 nm. As a by-product of the methodology, effective leaf area index (LAIe) estimates were derived and compared to hemispherical photography values. To assess the influence of LiDAR aggregation area size on the estimates in a sparse canopy environment, LiDAR CHPs and LAIes were generated by aggregating waveforms to plot- and site-level footprints (plot/site-aggregated) as well as in 5 m grids (grid-processed). LiDAR profiles were then compared to field biomass profiles generated based on field tree measurements. The correlation between field and LiDAR profiles was very high, with a mean R2 of 0.75 at plot-level and 0.86 at site-level for 55 plots and the corresponding 11 sites. Gridding had almost no impact on the correlation between LiDAR and field profiles (only marginally improvement), nor did the dataset-adjusted reflectance ratio. However, gridding and the dataset-adjusted reflectance ratio were found to improve the correlation between raw-waveform LiDAR and hemispherical photography LAIe estimates, yielding the highest correlations of 0.61 at plot-level and of 0.83 at site-level. This proved the validity of the approach and superiority of dataset-adjusted reflectance ratio of Armston et al. (2013) over a fixed ratio of 0.5 for LAIe estimation, as well as showed the adequacy of small-footprint LiDAR data for LAIe estimation in discontinuous canopy forests. Numéro de notice : A2015-702 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2015.03.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2015.03.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78338
in ISPRS Journal of photogrammetry and remote sensing > vol 104 (June 2015) . - pp 144 - 157[article]Retrieving surface variables by integrating ground measurements and earth observation data in forest canopies : a case study in Speuldersbos forest / Kitsiri Weligepolage (2015)
Titre : Retrieving surface variables by integrating ground measurements and earth observation data in forest canopies : a case study in Speuldersbos forest Type de document : Thèse/HDR Auteurs : Kitsiri Weligepolage, Auteur Editeur : Enschede [Pays Bas] : University of Twente Année de publication : 2015 Collection : ITC Dissertation num. 269 Importance : 148 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-90-365-3876-3 Note générale : bibliographie
University of Twente, Faculty of Geo-Information and Earth ObservationLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] aiguille
[Termes IGN] albedo
[Termes IGN] canopée
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] Fagus (genre)
[Termes IGN] hauteur des arbres
[Termes IGN] image AHS
[Termes IGN] image thermique
[Termes IGN] modèle numérique de surface de la canopée
[Termes IGN] Pinophyta
[Termes IGN] Pseudotsuga menziesii
[Termes IGN] réflectance végétale
[Termes IGN] rugosité
[Termes IGN] température au solRésumé : (auteur) The main objective of this study is to integrate tower-based measurements with ED data for estimating spatially and temporally distributed surface variables of a forest canopy for improved quantification of surface-atmosphere interactions. This study mainly focuses on three of the most important surface variables for estimating surface fluxes, namely the aerodynamic roughness, land surface albedo and land surface temperature.
In chapter 2, a framework is presented for estimating aerodynamic roughness parameters: the momentum roughness length (z0) and the displacement height (do) of a coniferous forest stand using remote sensing data. The specific objective of the study is to make use of high resolution Terrestrial Laser Scanning (TLS) data together with Airborne Laser Scanning (ALS) data to digitally map the upper canopy surface in order to generate high resolution digital Canopy Height Models (CHMs). The digital CHMs were subsequently used to extract surface geometric parameters of the upper canopy surface. Eventually the surface geometric parameters were used as input variables in the selected morphometric models to estimate aerodynamic roughness parameters. It was observed that the estimated values of zo and do depend very much on the selected model. Comparison of model estimated roughness parameters against the literature values for similar surface types has shown that the technique can be successfully applied to estimate forest surface roughness by tuning some of the model parameters to resemble the forest structure of the study area.
Chapter 3 describes the use of these two aerodynamic methods to estimate momentum roughness length and displacement height of Douglas fir forest using simultaneous micrometeorological and flux measurements. When the flux-gradient method was used to objectively determine zo and do, corrections for roughness sub-layer effects proved to be important. A new iterative method is employed to solve the set of equations when the corrections were made. In the absence of experimentally determined roughness sub-layer height, the corrections of Harman and Finnigan (2007) yielded the best overall estimates of aerodynamic parameters. Comparison with results of over 25 other studies has shown that the results obtained in this work fit the general trend rather well. Two quadratic relationships are proposed to predict do and ha based on the observed mean tree height. These simple relationships can be easily incorporated to large scale land surface models, provided that spatially distributed tree height information is available. The flux-variance technique is shown to be robust even when measurements are made in the roughness sub-layer. However the technique cannot be objectively used to estimate zo and do as no explicit method exists to select the exact value for coefficient C1.
A detailed investigation of stand level surface albedo variability of a patchwork forest is presented in chapter 4. The top of the canopy reflectance in the visible and near-infrared domain retrieved from airborne and satellite imageries were integrated to estimate spatially distributed surface albedo while the tower-based radiation measurements in the solar-reflective region were used to obtain the temporal variation of surface albedo over a needleleaf forest canopy. The diurnal variation of surface albedo is consistent with the previous findings for needleleaf forest canopies. The spatial mean surface albedo values estimated from remote sensing data for needleleaf (pure Douglas fir), broadleaf (pure Beech) and mixed forest classes are 0.09, 0.13 and 0.11 respectively. Both visual characteristics and descriptive statistics indicate that with increased pixel size, the spatial variability of albedo progressively decreases. The semivariogram analysis was more insightful to perceive the nature and causes of albedo spatial variability in different forest classes in relation to sensor spatial resolution.
Finally a theoretical basis for directional LST estimation from top of the atmosphere radiance measurements is presented along with a spatio-temporal analysis of remotely sensed LST and concurrently carried out ground-based radiation together with contact temperature measurements in a Douglas fir forest. For the analysis we used remotely sensed TIR data from Airborne Hyperspectral Scanner to estimate spatially distributed LST of forested area. The AHS sensor, with 10 thermal bands covering the range between 8 and 13pm of the electromagnetic spectrum is an example of the new generation of airborne sensors with multispectral thermal infrared capabilities. The data acquired from the AHS sensors provided the opportunity to retrieve the directional LST of the forest canopy with a very high spatial resolution for both nadir and oblique view angles. Also the concurrent tower-based temperature measurements provided limited ground truth for a spatio-temporal analysis of surface temperature in an area covered with Douglas fir trees. The method adopted here for concurrent determination of LST and LSE is the widely-used TES algorithm together with the MODTRAN4 preprocessor for calculating the required atmospheric contributions. AHS derived average temperature values are generally in good agreement with the tower based component temperature measured at 24 m level whereas the component temperatures (trunk) measured at 17 m are consistently higher. It may be noted that in comparison with off-nadir radiometric temperature the TES method provides average LST with RMSE around 1.9K while the corresponding value with respect to component temperature measured at 24 m is around 1.4 K.Note de contenu : 1- Introduction
2- Estimation of canopy aerodynamic roughness using morphometric methods
3- Effects of sub-layer corrections on the roughness parametrization of a Douglas fir forest
4- Effects of spatial resolution on estimating surface albedo
5- Retrieving directional temperature using multiplatform thermal data
6- Conclusion and recommendationsNuméro de notice : 14944 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Thèse étrangère Note de thèse : PhD : Geo-Information and Earth Observation : University of Twente : 2015 En ligne : https://research.utwente.nl/en/publications/retrieving-surface-variables-by-inte [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77060 Documents numériques
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14944 Retrieving surface variablesAdobe Acrobat PDF Individual tree segmentation over large areas using airborne LiDAR point cloud and very high resolution optical imagery / Yuchu Qin (2014)
Titre : Individual tree segmentation over large areas using airborne LiDAR point cloud and very high resolution optical imagery Type de document : Article/Communication Auteurs : Yuchu Qin, Auteur ; António Ferraz , Auteur ; Clément Mallet , Auteur ; Corina Iovan , Auteur Editeur : New York : Institute of Electrical and Electronics Engineers IEEE Année de publication : 2014 Conférence : IGARSS 2014, International Geoscience And Remote Sensing Symposium 13/07/2014 18/07/2014 Québec Québec - Canada Proceedings IEEE Importance : pp 800 - 803 Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] algorithme de décalage moyen
[Termes IGN] arbre (flore)
[Termes IGN] chaîne de traitement
[Termes IGN] détection d'arbres
[Termes IGN] diamètre des arbres
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] France (administrative)
[Termes IGN] image à très haute résolution
[Termes IGN] image optique
[Termes IGN] inventaire forestier (techniques et méthodes)
[Termes IGN] modèle numérique de surface de la canopée
[Termes IGN] peuplement forestier
[Termes IGN] segmentation d'image
[Termes IGN] semis de points
[Termes IGN] Ventoux, MontRésumé : (auteur) Timely and accurate measurements of forest parameters are critical for ecosystem studies, sustainable forest resources management, monitoring and planning. This paper presents a processing chain for individual tree segmentation over large areas with airborne LiDAR 3D point cloud and very high resolution (VHR) optical imagery. The proposed processing chain consists of forest stand level delineation with optical imagery, individual tree segmentation with Canopy Height Model (CHM) derived from LiDAR point cloud, rough characterization of trees at forest stand level, and point clustering of individual tree with an Adaptive Mean Shift 3D (AMS3D) algorithm. The processing chain is developed with the expectation of supporting operational forest inventory at individual tree level. Experiment is conducted using LiDAR data acquired in Ventoux region, France. Results suggest that the proposed processing chain can be successfully adopted for individual tree characterization over large areas with different forest stands. Numéro de notice : C2014-025 Affiliation des auteurs : LASTIG MATIS+Ext (2012-2019) Thématique : IMAGERIE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1109/IGARSS.2014.6946545 Date de publication en ligne : 06/11/2014 En ligne : http://dx.doi.org/10.1109/IGARSS.2014.6946545 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92034 Documents numériques
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Individual tree segmentation ... - pdf auteurAdobe Acrobat PDF A photogrammetric workflow for the creation of a forest canopy height model from small unmanned aerial system imagery / Jonathan Lisein in Forests, vol 4 n° 4 (december 2013)PermalinkSingle tree detection from airborne laser scanning data using a marked point process based method / Junjie Zhang in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol II-3 W1 (May 2013)PermalinkMulti-level filtering segmentation to measure individual tree parameters based on Lidar data: Application to a mountainous forest with heterogeneous stands / Cédric Vega in International journal of applied Earth observation and geoinformation, vol 13 n° 4 (August 2011)PermalinkCanopy surface topography in a French Guiana forest and the folded forest theory / P. Birnbaum in Plant ecology, vol 153 n° 1-2 (April 2001)Permalink