Centre de documentation
scientifique

Effects of forest structure and airborne laser scanning point cloud density on 3D delineation of individual tree crowns / Kaja Kandare in European journal of remote sensing, vol 49 n° 1 (2016)  

Public [article]  inEuropean journal of remote sensing > vol 49 n° 1 (2016) . - pp 337 - 359 Titre : Effects of forest structure and airborne laser scanning point cloud density on 3D delineation of individual tree crowns Type de document : Article/Communication Auteurs : Kaja Kandare, Auteur ; Hans Ole Ørka, Auteur ; Jonathan Cheung-Wai Chan, Auteur ; Michele Dalponte, Auteur Année de publication : 2016 Article en page(s) : pp 337 - 359 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] Alpes [Termes IGN] délimitation [Termes IGN] densité des points [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] forêt alpestre [Termes IGN] houppier [Termes IGN] Italie [Termes IGN] semis de points [Termes IGN] structure d'un peuplement forestier Résumé : (auteur) This paper presents a 3D delineation method for airborne laser scanning point cloud. The method is based on an unsupervised clustering technique applied on horizontal slices followed by vertical merging based on overlapping among clusters. On an Alpine forest dataset, we analysed the effects of different forest structures and point cloud densities on tree crown delineation. Forest structure affects mainly the omission error, which eases with homogeneous tree spacing and sizes, while on the commission error forest structure has only slight effect. Delineation accuracy increases with higher point densities where Mann-Whitney-Wilcoxon test shows that accuracy differences between thinned data and original data are statistically significant. Numéro de notice : A2016-829 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.5721/EuJRS20164919 En ligne : http://dx.doi.org/10.5721/EuJRS20164919 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82709 [article]

Assessing forest inventory information obtained from different inventory approaches and remote sensing data sources / Even Bergseng in Annals of Forest Science, vol 72 n° 1 (January 2015)  

Public [article]  inAnnals of Forest Science > vol 72 n° 1 (January 2015) . - pp 33 - 45 Titre : Assessing forest inventory information obtained from different inventory approaches and remote sensing data sources Type de document : Article/Communication Auteurs : Even Bergseng, Auteur ; Hans Ole Ørka, Auteur ; Erik Naesset, Auteur ; Terje Gobakken, Auteur Année de publication : 2015 Article en page(s) : pp 33 - 45 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] données multisources [Termes IGN] économie [Termes IGN] étude d'impact [Termes IGN] évaluation des données [Termes IGN] forêt boréale [Termes IGN] inventaire forestier (techniques et méthodes) [Termes IGN] inventaire forestier étranger (données) [Termes IGN] Norvège [Termes IGN] précision des données [Termes IGN] valeur économique Résumé : (auteur) Context : Evaluations of forest inventories usually end when accuracy and precision have been quantified. Aims : We aim to value the accuracy of information derived from different remote sensing sensors (airborne laser scanning, aerial multispectral and hyperspectral imagery) and four alternative forest inventory approaches. Methods : The approaches were (1) mean values or (2) diameter distributions both obtained by the area-based approach (ABA), (3) individual tree crown (ITC) segmentation and (4) an approach called semi-individual tree crown (SITC) segmentation. The estimated tree information was assessed and used to evaluate how erroneous inventory data affect economic value and loss due to suboptimal harvesting decisions. Field measured data used as reference come from 23 field plots collected in a study area in south-eastern Norway typical of managed boreal forests in Norway. Results : The accuracy of the forest inventory was generally in line with previous studies. Our results show that using mean values from the area-based approach may yield large economic losses, while adding a diameter distribution to the area-based approach yielded less loss than the individual tree crown methods. Adding information from imagery had little effect on the results. Conclusions : Taking inventory costs into account, diameter distributions from the area-based approach without additional information seems favourable. Numéro de notice : A2015-380 Affiliation des auteurs : non IGN Thématique : FORET/GEOMATIQUE Nature : Article DOI : 10.1007/s13595-014-0389-x Date de publication en ligne : 04/06/2014 En ligne : https://doi.org/10.1007/s13595-014-0389-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76865 [article]

Range and AGC normalization in airborne discrete-return LiDAR intensity data for forest canopies / Ilkka Korpela in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 4 (July - August 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 4 (July - August 2010) . - pp 369 - 379 Titre : Range and AGC normalization in airborne discrete-return LiDAR intensity data for forest canopies Type de document : Article/Communication Auteurs : Ilkka Korpela, Auteur ; Hans Ole Ørka, Auteur ; Juha Hyyppä, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 369 - 379 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] couvert forestier [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] espèce végétale [Termes IGN] Finlande [Termes IGN] forêt boréale [Termes IGN] lasergrammétrie [Termes IGN] Pinophyta [Termes IGN] précision de la classification [Termes IGN] signal laser Résumé : (Auteur) Recently, the intensity characteristics of discrete-return LiDAR sensors were studied for vegetation classification. We examined two normalization procedures affecting LiDAR intensity through the scanning geometry and the system settings, namely, range normalization and the effects of the automatic gain control (AGC) in the Optech ALTM3100 and Leica ALS50-II sensors. Range normalization corresponds to weighting of the observed intensities with the term (R/RRef)a , where R is the range, RRef is a mean reference range, and aset membership, variant[2,4] is the exponent that is, according to theory, dependent on the target geometry. LiDAR points belonging to individual tree crowns were extracted for 13 887 trees in southern Finland. The coefficient of variation (CV) of the intensity was analyzed for a range of values of exponent a. The tree species classification performance using 13 intensity variables was also used for sensitivity analysis of the effect of a. The results were in line with the established theory, since the optimal level of a was lower (a~2) for trees with large or clumped leaves and higher (a~3) for diffuse coniferous crowns. Different echo groups also showed varying responses. Single-return pulses that represented strong reflections had a lower optimal value of a than the first and all echoes in a pulse. The gain in classification accuracy from the optimal selection of the exponent was 2%–3%, and the optimum for classification was different from that obtained using the CV analysis. In the ALS50-II sensor, the combined and optimized AGC and R normalizations had a notably larger effect (6%–9%) on classification accuracy. Our study demonstrates the ambiguity of R normalization in vegetation canopies. Numéro de notice : A2010-297 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2010.04.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2010.04.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30491 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-2010041	SL	Revue	Centre de documentation	Revues en salle	Disponible