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Small-footprint laser scanning simulator for system validation, error assessment, and algorithm development / Antero Kukko in Photogrammetric Engineering & Remote Sensing, PERS, vol 75 n° 10 (October 2009)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 75 n° 10 (October 2009) . - pp 1177 - 1189 Titre : Small-footprint laser scanning simulator for system validation, error assessment, and algorithm development Type de document : Article/Communication Auteurs : Antero Kukko, Auteur ; Juha Hyyppä, Auteur Année de publication : 2009 Article en page(s) : pp 1177 - 1189 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] classification orientée objet [Termes IGN] détection de changement [Termes IGN] données lidar [Termes IGN] erreur systématique [Termes IGN] faisceau laser [Termes IGN] hauteur des arbres [Termes IGN] instrumentation Toposys [Termes IGN] modèle de simulation [Termes IGN] précision décimétrique [Termes IGN] semis de points [Termes IGN] signal laser [Termes IGN] télémétrie laser aéroporté Résumé : (Auteur) Airborne lidar systems have come to be extensively used in photogrammetry and mapping sciences. In this paper, a high-quality simulation approach and methods of smallfootprint lidar processing are presented and discussed, validated for tree height estimation, and demonstrated for scanning geometry effects analysis and mobile mapping. The simulation method implemented combines both spatial and radiometric components to produce realistic waveform and point cloud data for system performance analysis and for algorithm development for lidar data processing and mapping purposes. Waveform data generated by the simulator were shown to demonstrate the possibilities of such an approach in system and data verification. As the related empirical data are insufficient for effective research and exploitation in mapping purposes at the moment, the simulated waveform data are needed. A tree location accuracy of 15 cm and tree height underestimation of 0.33 m was found using the simulation model for the TopEye Mk II laser scanner, compared to the artificial forest model reference data. Modeling of light interaction on object surfaces and characteristics of scanning systems provide an opportunity to simulate laser data acquisition of well-defined objects under controlled conditions. By eliminating different sources of error case-by-case, we can improve the knowledge obtained merely from the experimental studies. Data validation in the scanning geometry simulations was carried out by comparing the simulated first echo data to the environment model and, separately, to the first echo data from an independent TopoSys II flight strip that was not used for the environment model computation. The mean differences reveal that the simulator slightly overestimates the object elevations. Deviation between the real TopoSys point cloud and the environmental model was 2 to 3 times larger than that obtained for the simulated Optech and TopoSys data sets. We believe that the developed simulation and modeling is an efficient tool for determining the most reasonable set of flight parameters for any current mapping task, for analyzing change detection possibilities of repeated laser surveys, and for studying and verifying future lidar systems and concepts. However, this requires high-quality modeling of the system and extensive knowledge of the interaction between the laser beam and the object, which should be further developed in the coming years. Copyright ASPRS Numéro de notice : A2009-419 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.75.10.1177 En ligne : https://doi.org/10.14358/PERS.75.10.1177 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30050 [article]

Assessment of the influence of flying altitude and scan angle on biophysical vegetation products derived from airborne laser scanning / F. Morsdorf in International Journal of Remote Sensing IJRS, vol 29 n° 5 (March 2008)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 29 n° 5 (March 2008) . - pp 1387 - 1406 Titre : Assessment of the influence of flying altitude and scan angle on biophysical vegetation products derived from airborne laser scanning Type de document : Article/Communication Auteurs : F. Morsdorf, Auteur ; O. Frey, Auteur ; E. Meier, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 1387 - 1406 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] altitude du capteur [Termes IGN] angle d'incidence [Termes IGN] angle de visée [Termes IGN] couvert végétal [Termes IGN] données laser [Termes IGN] hauteur des arbres [Termes IGN] instrumentation Toposys [Termes IGN] Leaf Area Index [Termes IGN] modèle numérique de terrain [Termes IGN] parc naturel [Termes IGN] plan de vol [Termes IGN] signal laser [Termes IGN] Suisse [Termes IGN] télémétrie laser aéroporté Résumé : (Auteur) Airborne Laser Scanning (ALS) has been established as a valuable tool for the estimation of biophysical vegetation properties such as tree height, crown width, fractional cover and leaf area index (LAI). It is expected that the conditions of data acquisition, such as viewing geometry and sensor configuration influence the value of these parameters. In order to gain knowledge about these different conditions, we test for the sensitivity of vegetation products for viewing geometry, namely flying altitude and scanning (incidence) angle. Based on two methodologies for single tree extraction and derivation of fractional cover and LAI previously developed and published by our group, we evaluate how these variables change with either flying altitude or scanning angle. These are the two parameters which often need to be optimized towards the best compromise between point density and area covered with a single flight line, in order to reduce acquisition costs. Our test-site in the Swiss National Park was sampled with two nominal flying altitudes, 500 and 900 m above ground. Incidence angle and local incidence angle were computed based on the digital terrain model using a simple backward geocoding procedure. We divided the raw laser returns into several different incident angle classes based on the flight path data; the TopoSys Falcon II system used in this study has a maximum scan angle of + 7.15°. We compared the derived biophysical properties from each of these classes with field measurements based on tachymeter measurements and hemispherical photographs, which were geolocated using differential GPS. It was found that with increasing flying height the well-known underestimation of tree height increases. A similar behaviour can be observed for fractional cover; its respective values decrease with higher flying height. The minimum distance between first and last echo increases from 1.2 metres for 500 m AGL to more than 3 metres for 900 m AGL, which does alter return statistics. The behaviour for incidence angles is not so evident, probably due to the small scanning angle of the system used. fCover seems to be most affected by incidence angles, with significantly higher differences for locations further away from nadir. As expected, incidence angle appears to be of higher importance for vegetation density parameters than local incidence angle. Numéro de notice : A2008-081 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160701736349 En ligne : https://doi.org/10.1080/01431160701736349 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29076 [article]

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Change detection techniques for canopy height growth measurements using airborne laser scanner data / X. Yu in Photogrammetric Engineering & Remote Sensing, PERS, vol 72 n° 12 (December 2006)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 72 n° 12 (December 2006) . - pp 1339 - 1348 Titre : Change detection techniques for canopy height growth measurements using airborne laser scanner data Type de document : Article/Communication Auteurs : X. Yu, Auteur ; Juha Hyyppä, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 1339 - 1348 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] analyse diachronique [Termes IGN] détection de changement [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] forêt boréale [Termes IGN] hauteur des arbres [Termes IGN] houppier [Termes IGN] instrumentation Toposys [Termes IGN] modèle numérique de surface [Termes IGN] objet géographique ponctuel [Termes IGN] Pinus sylvestris [Termes IGN] semis de points Résumé : (Auteur) This paper analyzes the potential of airborne laser scanner data for measuring individual tree height growth in a boreal forest using 82 sample trees of Scots pine. Point clouds (10 points/m2, beam size 40 cm) illuminating 50 percent of the treetops were acquired in September 1998 and May 2003 with the Toposys 83 kHz lidar system. The reference height and height growth of pines were measured with a tacheometer in the field. Three different types of features were extracted from the point clouds representing each tree; they were the difference between the highest z values, the difference between the DSMs of the tree crown, and the differences between the 85th, 90th and 95th percentiles of the canopy height histograms corresponding to the crown. The best correspondence with the field measurements was achieved with an R2 value of 0.68 and a RMSE of 43 cm. The results indicate that it is possible to measure the growth of an individual tree with multi-temporal laser surveys. We also demonstrated a new algorithm for tree-to-tree matching. It is needed in operational growth estimation based on individual trees, especially in dense spruce forests. The method is based on minimizing the distances between treetops in the N- dimensional data space. The experiments showed that the use of the location (derived from laser data) and height of the trees were together adequate to provide reliable tree-to-tree matching. In the future, a fourth dimension (the crown area) should also be included in the matching. Copyright ASPRS Numéro de notice : A2006-543 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.72.12.1339 En ligne : https://doi.org/10.14358/PERS.72.12.1339 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28266 [article]

Digital Lagerichtige orthophotos und Lidar-hohenmodelle / U. Lohr in GIS Geo-Informations-Systeme, vol 2003 n° 3 (März 2003)

Public [article]  inGIS Geo-Informations-Systeme > vol 2003 n° 3 (März 2003) . - pp 26 - 29 Titre : Digital Lagerichtige orthophotos und Lidar-hohenmodelle Titre original : Digital true ortho-images and Lidar digital surface models Type de document : Article/Communication Auteurs : U. Lohr, Auteur Année de publication : 2003 Article en page(s) : pp 26 - 29 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Orthophotographie, orthoimage [Termes IGN] bâtiment [Termes IGN] correction géométrique [Termes IGN] données lidar [Termes IGN] image à haute résolution [Termes IGN] image aérienne [Termes IGN] image RVB [Termes IGN] instrumentation Toposys [Termes IGN] modèle numérique de surface [Termes IGN] orthoimage intégrale [Termes IGN] système d'information géographique Résumé : (Auteur) With increasing use of geographic information sytems (GIS) true ortho-projections gain more and more importance. True ortho-images are geometrically correct and can be overlayed and intersected with GIS date sources of all kind. A complete true ortho-computation requires a detailed digital surface model as input, which can be collected by the airborne laser scanning approach. The sensor package of TopoSys GmbH allows for a simultaneaous collection of high resolution height and multispectral image data. Using the image data of the TopoSys linear array scanner true orthophotos in RGB and infrared are derived through processing of the LIDAR digital surface model. Numéro de notice : A2003-027 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22324 [article]

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Réalisation de modèles numériques de terrain par levé laser aéroporté / M. Le Masson (2001)

Public Titre : Réalisation de modèles numériques de terrain par levé laser aéroporté Type de document : Mémoire Auteurs : M. Le Masson, Auteur Editeur : Champs-sur-Marne : Ecole nationale des sciences géographiques ENSG Année de publication : 2001 Importance : 34 p. Format : 21 x 30 cm Note générale : Bibliographie Rapport de projet pluridisciplinaire, IT2 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] données laser [Termes IGN] GPS-INS [Termes IGN] instrumentation Toposys [Termes IGN] lasergrammétrie [Termes IGN] modèle numérique de surface [Termes IGN] modèle numérique de terrain [Termes IGN] photodiode [Termes IGN] positionnement par GPS [Termes IGN] système d'information géographique [Termes IGN] télémétrie laser aéroporté Index. décimale : PROJET Mémoires : Rapports de projet - stage des ingénieurs de 2e année Résumé : (Auteur) Ce rapport est un tour d'horizon du levé laser aéroporté... vu de l'intérieur. Il traite successivement des enjeux, des techniques, de la pratique et des applications du levé laser. Note de contenu : : 1. ENVIRONNEMENT DU LEVE LASER 1.1.La troisième dimension 1.2.Le marché du levé laser 1.3.Les forces en présence 1.4.Biographie de Toposys 2. PRINCIPES DU LEVE LASER AEROPORTE 2.1. Mesurer une distance avec un laser -.Les différents types de Laser -.Méthodes de mesure -.Techniques de balayage 2.2.Le système Toposys -.Architecture -.Caractéristiques -.Précision -.Les composantes du système 3. PRATIQUER LE LEVE LASER AEROPORTE 3.1.Mission aérienne -.Préparation du plan de vol -.Le jour du vol... 3.2.Traitement -.Traitement des données brutes -.Réalisation de modèles numériques 4. APPLICATIONS 4.1.Illustrations générales -.NINE en milieu urbain -.Gestion des ressources naturelles 4.2. Une utilisation spécique : Integrated Helicopter Corridor Mapping Conclusion Bibliographie Table des illustrations Numéro de notice : 13006 Affiliation des auteurs : IGN (1940-2011) Thématique : IMAGERIE Nature : Mémoire de projet pluridisciplinaire Organisme de stage : TopoSys (Allemagne) Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=49868

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