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Adaptive stopping criterion for top-down segmentation of ALS point clouds in temperate coniferous forests / Nina Amiri in ISPRS Journal of photogrammetry and remote sensing, vol 141 (July 2018)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 141 (July 2018) . - pp 265 - 274 Titre : Adaptive stopping criterion for top-down segmentation of ALS point clouds in temperate coniferous forests Type de document : Article/Communication Auteurs : Nina Amiri, Auteur ; Przemyslaw Polewski, Auteur ; Marco Heurich, Auteur ; Peter Krzystek, Auteur ; Andrew K. Skidmore, Auteur Année de publication : 2018 Article en page(s) : pp 265 - 274 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Bavière (Allemagne) [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] inventaire forestier (techniques et méthodes) [Termes IGN] inventaire forestier local [Termes IGN] lasergrammétrie [Termes IGN] Pinophyta [Termes IGN] segmentation [Termes IGN] semis de points [Vedettes matières IGN] Inventaire forestier Mots-clés libres : Bavarian Forest National Park Résumé : (auteur) The development of new approaches to individual tree crown delineation for forest inventory and management is an important area of ongoing research. The increasing availability of high density ALS (Airborne Laser Scanning) point clouds offers the opportunity to segment the individual tree crowns and deduce their geometric properties with a high level of accuracy. Top-down segmentation methods such as normalized cut are established approaches for delineation of single trees in ALS point clouds. However, overlapping crowns and branches of nearby trees frequently cause over- and under-segmentation due to the difficulty of defining a single criterion for stopping the partitioning process. In this work, we investigate an adaptive stopping criterion based on the visual appearance of trees within the point clouds. We focus on coniferous trees due to their well-defined crown shapes in comparison to deciduous trees. This approach is based on modeling the coniferous tree crowns with elliptic paraboloids to infer whether a given 3D scene contains exactly one or more than one tree. For each processed scene, candidate tree peaks are generated from local maxima found within the point cloud. Next, paraboloids are fitted at the peaks using a random sample consensus procedure and classified based on their geometric properties. The decision to stop or continue partitioning is determined by finding a set of non-overlapping paraboloids. Experiments were performed on three plots from the Bavarian Forest National Park in Germany. Based on validation data from the field inventory, results show that our approach improves the segmentation quality by up to 10% across plots with different properties, such as average tree height and density. This indicates that the new adaptive stopping criterion for normalized cut segmentation is capable of delineating tree crowns more accurately than a static stopping criterion based on a constant Ncut threshold value. Numéro de notice : A2018-670 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2018.05.006 Date de publication en ligne : 29/05/2018 En ligne : https://doi.org/10.1016/j.isprsjprs.2018.05.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90405 [article]

Exemplaires(3)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-2018071	RAB	Revue	Centre de documentation	En réserve L003	Disponible
081-2018073	DEP-EXM	Revue	LASTIG	Dépôt en unité	Exclu du prêt
081-2018072	DEP-EAF	Revue	Nancy	Dépôt en unité	Exclu du prêt

Detection of fallen trees in ALS point clouds using a Normalized Cut approach trained by simulation / Przemyslaw Polewski in ISPRS Journal of photogrammetry and remote sensing, vol 105 (July 2015)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 105 (July 2015) . - pp 252 - 271 Titre : Detection of fallen trees in ALS point clouds using a Normalized Cut approach trained by simulation Type de document : Article/Communication Auteurs : Przemyslaw Polewski, Auteur ; Wei Yao, Auteur ; Marco Heurich, Auteur ; Peter Krzystek, Auteur ; Uwe Stilla, Auteur Année de publication : 2015 Article en page(s) : pp 252 - 271 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] arbre mort [Termes IGN] Bavière (Allemagne) [Termes IGN] détection automatique [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] inventaire forestier local [Termes IGN] parc naturel national [Termes IGN] semis de points Résumé : (auteur) Downed dead wood is regarded as an important part of forest ecosystems from an ecological perspective, which drives the need for investigating its spatial distribution. Based on several studies, Airborne Laser Scanning (ALS) has proven to be a valuable remote sensing technique for obtaining such information. This paper describes a unified approach to the detection of fallen trees from ALS point clouds based on merging short segments into whole stems using the Normalized Cut algorithm. We introduce a new method of defining the segment similarity function for the clustering procedure, where the attribute weights are learned from labeled data. Based on a relationship between Normalized Cut’s similarity function and a class of regression models, we show how to learn the similarity function by training a classifier. Furthermore, we propose using an appearance-based stopping criterion for the graph cut algorithm as an alternative to the standard Normalized Cut threshold approach. We set up a virtual fallen tree generation scheme to simulate complex forest scenarios with multiple overlapping fallen stems. This simulated data is then used as a basis to learn both the similarity function and the stopping criterion for Normalized Cut. We evaluate our approach on 5 plots from the strictly protected mixed mountain forest within the Bavarian Forest National Park using reference data obtained via a manual field inventory. The experimental results show that our method is able to detect up to 90% of fallen stems in plots having 30–40% overstory cover with a correctness exceeding 80%, even in quite complex forest scenes. Moreover, the performance for feature weights trained on simulated data is competitive with the case when the weights are calculated using a grid search on the test data, which indicates that the learned similarity function and stopping criterion can generalize well on new plots. Numéro de notice : A2015-703 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2015.01.010 En ligne : https://doi.org/10.1016/j.isprsjprs.2015.01.010 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78339 [article]

Lidar strip adjustment with automatically reconstructed roof shapes / M. Rentsch in Photogrammetric record, vol 27 n° 139 (September - November 2012)  

Public [article]  inPhotogrammetric record > vol 27 n° 139 (September - November 2012) . - pp 272 - 292 Titre : Lidar strip adjustment with automatically reconstructed roof shapes Type de document : Article/Communication Auteurs : M. Rentsch, Auteur ; Peter Krzystek, Auteur Année de publication : 2012 Article en page(s) : pp 272 - 292 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] compensation par bloc [Termes IGN] densité des points [Termes IGN] données lidar [Termes IGN] erreur systématique [Termes IGN] étalonnage d'instrument [Termes IGN] lidar à retour d'onde complète [Termes IGN] ligne de visée [Termes IGN] photogrammétrie terrestre [Termes IGN] points homologues [Termes IGN] reconstruction 3D du bâti [Termes IGN] semis de points [Termes IGN] toit Résumé : (Auteur) In recent years, the performance of lidar systems has steadily improved due to an increase in the achievable point density. The main error sources affecting the quality of lidar-derived secondary products such as digital terrain models (DTMs) and digital surface models (DSMs) are the result of systematic errors coming from insufficient boresight calibration. The effects of boresight misalignments are visually recognised as discrepancies of the laser point clouds at selected objects (such as building roofs) in overlapping areas of neighbouring lidar strips. In this work, a strip adjustment method is presented that corrects the systematic errors of the laser point cloud using five strip parameters (three shifts plus two angular corrections for heading and roll). The strip adjustment procedure uses 2D and 3D tie elements and takes advantage of a new 3D measurement technique applied to building roofs. The strip adjustment method is applied to three different datasets, consisting of conventional first/last pulse and full-waveform data. The results show that systematic discrepancies are typical for datasets that have already been processed by the flight companies. These errors can be reduced by more than 70% by applying the new strip adjustment approach. Preliminary investigations indicate that a higher laser point density and the inclusion of intensity and pulse width within full-waveform lidar data lead to better results. Numéro de notice : A2012-462 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00690.x Date de publication en ligne : 18/09/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00690.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31908 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
106-2012031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Theoretische und experimentelle Genauigkeitsuntersuchungen für ein optisches Positionsmeßsystem zur hochgenauen Vermessung von bewegten Objekten / Peter Krzystek (1990)

Public Titre : Theoretische und experimentelle Genauigkeitsuntersuchungen für ein optisches Positionsmeßsystem zur hochgenauen Vermessung von bewegten Objekten Titre original : [Etude de la précision théorique et expérimentale d'un système optique de mesure de position pour une mesure de haute précision d'objets en mouvements] Type de document : Thèse/HDR Auteurs : Peter Krzystek, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 1990 Collection : DGK - C Sous-collection : Dissertationen num. 363 Importance : 110 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-9411-6 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie [Termes IGN] capteur optique [Termes IGN] chambre DTC [Termes IGN] erreur systématique [Termes IGN] étalonnage d'instrument [Termes IGN] interpolation bilinéaire [Termes IGN] modèle mathématique [Termes IGN] objet mobile [Termes IGN] photodiode [Termes IGN] précision géométrique (imagerie) Index. décimale : 30.03 Instruments de géodésie Numéro de notice : 59846 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=60645

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
59846-01	30.03	Livre	Centre de documentation	En réserve M-103	Disponible