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Initial analysis and visualization of waveform laser scanner data / Johanna Töpel (2005)

Public Titre : Initial analysis and visualization of waveform laser scanner data Type de document : Mémoire Auteurs : Johanna Töpel, Auteur Editeur : Linköping [Suède] : Linköping Institute of Technology Année de publication : 2005 Importance : 63 p. Format : 21 x 30 cm Note générale : bibliographie Master’s Thesis in Automatic Control Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] algorithme espérance-maximisation [Termes IGN] canopée [Termes IGN] classification orientée objet [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] faisceau laser [Termes IGN] forêt [Termes IGN] forme d'onde [Termes IGN] forme d'onde pleine [Termes IGN] impulsion laser [Termes IGN] semis de points [Termes IGN] signal laser [Termes IGN] visualisation 3D Résumé : (auteur) Conventional airborne laser scanner systems output the three-dimensional coordinates of the surface location hit by the laser pulse. Data storage capacity and processing speeds available today has made it possible to digitally sample and store the entire reflected waveform, instead of only extracting the coordinates. Research has shown that return waveforms can give even more detailed insights into the vertical structure of surface objects, surface slope, roughness and reflectivity than the conventional systems. One of the most important advantages with registering the waveforms is that it gives the user the possibility to himself define the way range is calculated in post-processing. In this thesis different techniques have been tested to visualize a waveform data set in order to get a better understanding of the waveforms and how they can be used to improve methods for classification of ground objects. A pulse detection algorithm, using the EM algorithm, has been implemented and tested. The algorithm output position and width of the echo pulses. One of the results of this thesis is that echo pulses reflected by vegetation tend to be wider than those reflected by for example a road. Another result is that up till five echo pulses can be detected compared to two echo pulses that the conventional system detects. Note de contenu : Introduction 1- Registred waveform 2- Lidar data 3- Documentation of waveforms 4- Vizualisation 5- Pulse detection 6- Extracted points 7- Discussion Numéro de notice : 21710 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Mémoire masters divers Organisme de stage : Swedish Defence Research Agency FOI Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90997