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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Laserový projektor / Laser Projector

Svoboda, Pavel January 2015 (has links)
The aim of this thesis is to create a system, which draws the graphics with the help of a set laser project and eventually is able to synthetize several coloured rays and thus realise a multicolour drawing. The whole system is controlled by a Raspberry PI microcomputer and the data is sent to it from a PC via an Ethernet cable. The transmission of the projector device was identified and possible ways of improving the device were suggested. The results of this thesis allow creation of a multi-coloured vector picture, transferring it into the device and depiction on the project desktop. The whole device can therefore be used for example for the purpose of a presentation.
62

Aplikace SLAM algoritmů pro vozidlo s čtyřmi řízenými koly / Application of SLAM algorithms for 4WS vehicle

Najman, Jan January 2015 (has links)
This paper deals with the application of SLAM algorithms on experimental four wheel vehicle Car4. The first part shows the basic functioning of SLAM including a description of the extended Kalman filter, which is one of its main components. Then there is a brief list of software tools available to solve this problem in the environment of MATLAB and an overview of sensors used in this work. The second part presents methodology and results of the testing of individual sensors and their combinations to calculate odometry and scan the surrounding space. It also shows the process of applying SLAM algorithms on Car4 vehicle using the selected sensors and the results of testing of the entire system in practice.
63

Surface curvature of pelvic joints from three laser scanners: separating anatomy from measurement error.

Villa, C., Gaudio, D., Cattaneo, C., Buckberry, Jo, Wilson, Andrew S., Lynnerup, N. 16 April 2014 (has links)
Yes / Recent studies have reported that quantifying symphyseal and auricular surfaces curvature changes on 3D models acquired by laser scanners have a potential for age estimation. However, no tests have been carried out to evaluate the repeatability of the results between different laser scanners. 3D models of the two pelvic joints were generated using three laser scanners (Custom, Faro, Minolta). The surface curvature, the surface area and the distance between co-registered meshes were investigated. Close results were found for surface areas (differences between 0.3% and 2.4%) and for distance deviations (average < 20 μm, SD < 200 μm). The curvature values were found to be systematically biased between different laser scanners, but still showing similar trends with increasing phases / scores. Applying a smoothing factor to the 3D models, it was possible to separate anatomy from the measurement error of each instrument, so that similar curvature values could be obtained (p < 0.05) independent of the specific laser scanner. / The full text was made available at the end of the publisher's embargo: 31st March 2016
64

3D lazerinių matavimo sistemų ypatumai / Features of the 3D lasers measurement systems

Melaika, Stasys 16 June 2010 (has links)
Magistrantūros baigiamojo darbo tikslas yra išanalizuoti 3D lazerines matavimo sistemas, jų panaudojimą geodeziniams darbams ir palyginti su elektroniniu tacheometru. Atliekant tyrimą buvo panaudoti teoriniai bei praktiniai duomenys ir sisteminė analizė. Tyrimo objektas- stacionarus lazerinis skeneris Riegl LMS-Z420i. Pasirinktas prietaisas yra kol kas vienintelis toks Lietuvoje. Modernios technologijos su naujausiais techniniais sprendimais dėl savo produktyvumo gauna vis didesnę reikšmę geodezijoje. Todėl būtina žinoti jų veikimo principus ir panaudojimo galimybes. 3D lazerinės matavimų sistemos palyginti su elektroniniais tachometrais yra naujas dalykas. 3D lazerinės matavimų sistemos - tai įrenginiai, 3D skeneriai, kurie analizuoja realaus pasaulio objektą ir jo aplinką, siekiant surinkti duomenis apie jo formą ir jo išvaizdą (t.y. spalvą). Surinkti duomenys gali būti naudojami kurti skaitmeninius trimačius modeliu- tai informacija naudinga įvairioms programoms. Šie prietaisai yra plačiai naudojami topografiniuose darbuose, kalnakasyboje, fasadų matavimams, pastatų inventorizacijai, miestų modeliavimui. Taip pat ši technologija apima pramoninio dizaino, protezavimo, prototipų kūrimo, kokybės kontrolės tikrinimo funkcijas. Darbe išanalizuoti lazerinis skeneris Riegl LMS-Z420i, jo parametrai bei funkcijos, matavimo technologija ir palyginta matavimo sparta, tikslumas ir duomenų apdorojimas su elektroniniu tacheometru Sokkia set 5x. Atlikus palyginimą lazerinis skeneris... [toliau žr. visą tekstą] / Magister thesis is to analyze the 3D laser measurement systems, the use of geodetic work and compared with an electronic tachometer having. The study was theoretical and practical use of data and systematic analysis. The object of the stationary-laser scanner Riegl LMS-Z420i. The selected device is so far the only one in Lithuania. Modern technology with the latest technical solutions for its performance are receiving an increasing larger role in geodesy. Therefore, it is necessary to know the principles of operation and usability. 3D laser measurement system in relation to electronic tachometer is a new thing. 3D laser measurement system - a device, 3D scanners, which examines real-world object and its environment in order to collect data about its shape and its appearance (ie color). The data collected can be used to create digital three-dimensional model, this information is useful for various applications. These devices are widely used for topographical works, mining, facade measurements, building inventory, urban simulation. Also, this technology include industrial design, prosthetics, prototype development, quality control inspection functions. The paper analyzed a laser scanner Riegl LMS-Z420i, its parameters and functions, measurement techniques and compared the measurement speed, accuracy and data processing with an electronic tacheometer having Sokkia Set 5x. After a comparison of laser scanner Riegl LMS-Z420i has superior electronic tachometers Sokkia Set 5x.
65

Contribution à la reconstruction 3D de bâtiments à partir de nuage de points de scanner laser terrestre / A contribution to 3D building reconstruction from terrestrial laser scanner points cloud

Bennis, Abdelhamid 02 October 2015 (has links)
La rénovation et la réhabilitation énergétique du parc de bâtiment est un des grands défis identifiés pour les décennies à venir. Devant cet impératif d'une rénovation d'ampleur du parc construit, les solutions techniques utilisant des ossatures rapportées sont employées de plus en plus fréquemment car elles permettent de combiner performance thermique, renouvellement esthétique et ajouts fonctionnels. Une des difficultés dans l'amélioration et l'automatisation des projets de rénovation est liée à la connaissance de la géométrie du bâti existant. Des plans de l'état existant ne sont pas toujours disponibles, et dans le cas échéant, ne sont pas forcément exacts en raison de modifications apportées au bâti et non documentées ou d'écarts initiaux entre les plans et la réalisation. Après une étude bibliographique des méthodes existantes détaillées dans le chapitre 1. Les travaux menés dans le cadre d'une collaboration entre le CRITT Bois et le CRAN ont permis de développer une méthode automatique de reconstruction 3D du modèle de bâtiments à partir de nuages de points obtenus par scanner LASER terrestre. La méthode proposée se décompose en trois phases principales. La première phase détaillée dans le deuxième chapitre, consiste à segmenter le nuage de points en plusieurs plans représentants les façades du bâtiment. L'exploitation de la colorimétrie durant la phase de segmentation du nuage de points permet une réduction importante de la complexité de l'algorithme de segmentation géométrique. L'approche consiste à effectuer dans un premier temps une classification préalable du nuage de points en se basant sur les informations colorimétriques de chaque point. Puis, dans un second temps, il s'agit d'effectuer une segmentation géométrique du nuage de points en utilisant un algorithme de segmentation robuste (RANSAC). Le chapitre 3 présente la deuxième phase qui consiste à modéliser le pas d'échantillonnage de la surface à partir duquel on définit le seuil d'extraction des points de contours. Le but étant d'améliorer la fiabilité d'extraction des points de contours, ainsi que l'approximation de l'erreur sur le modèle. Le chapitre 4 détaille les principales étapes de la reconstruction d'un modèle filaire. Dans un premier temps les régions définies par les points de contours sont classées en Régions d'Irrégularités (RI), Régions d'Eléments Architecturaux (REA) comme les fenêtres et Régions de Façade (RF) représentées par les contours extérieurs de la façade. La deuxième étape consiste à modéliser les différentes régions, par un maillage de Delaunay pour les RI, et des polyèdres pour les RF et REA. La dernière étape calcule une approximation de l'erreur sur le modèle. Les tests de fiabilité de la méthode ont été réalisés sur des chantiers réels conduits par des industriels de la construction et de la rénovation. Il en ressort que la qualité de la reconstruction 3D reste fortement dépendante des facteurs d'acquisition ainsi que de la surface numérisée. L'approximation de l'erreur de modélisation permet ainsi de prévoir à l'avance les erreurs sur le modèle CAO. / The renovation and the improvement of the energy efficiency of existing housing stock is one of big challenges identified for coming decades. In front of this imperative, timber based elements for building renovation are more and more used due to their substantial improvement of the building insulation, aesthetic renewal and functional additions. However, this technology faces some difficulties, one of them is the improvement of the renovation projects automation, which is bound to the knowledge of the existing built geometry. The plans representing the existing state of the building are not always available, and if so, they may be not exact, because the modifications made on the building are usually undocumented. After a literature review of existing methods which are detailed the first chapter. The work within the framework of cooperation between the CRITTBois and CRAN have allowed to develop an automatic method for 3D building CAD model reconstruction from point clouds acquired by a terrestrial LASER scanner. The proposed method is composed of three main phases. The first one detailed in the second chapter, consists in segmenting the point cloud into planar patches representing the building facades. To decrease the segmentation algorithm complexity, the colorimetric information is also considered. The approach consists in making a colorimetric classification of the point cloud in a first step, then a geometrical segmentation of the point cloud using a robust segmentation algorithm (RANSAC). The third chapter presents the second phase of our approach consists in surface sampling steps modeling and boundary point extraction. Here, we consider a local threshold defined according to the approximated surface sampling steps. The aim of considering local threshold is to improve the reliability of the boundary point extraction algorithm and approximating the CAD model error. The last chapter presents the main three steps of the boundary model reconstruction method. The first step consists in classifying the regions defined by their boundary points into three types of regions: Irregularity Region (IR), Architectural Element Region (AER) as windows, and Facades Regions (FR) which represent the building facades defined by their outer boundaries. The second step consists in modeling these regions considering a Delaunay triangulation for the IR and a polyhedral model for the AER and the FR. The third step consists in making an approximation of the error in the model. The method reliability tests were conducted on real projects; they were performed by industrial construction and renovation professionals. The tests show that the quality of the 3D reconstruction remains strongly dependent to the acquisition factors and the scanned surface properties. Also, the approximation of the modeling error can predict in advance the errors on the CAD model.
66

Intelligent 3D seam tracking and adaptable weld process control for robotic TIG welding

Manorathna, Prasad January 2015 (has links)
Tungsten Inert Gas (TIG) welding is extensively used in aerospace applications, due to its unique ability to produce higher quality welds compared to other shielded arc welding types. However, most TIG welding is performed manually and has not achieved the levels of automation that other welding techniques have. This is mostly attributed to the lack of process knowledge and adaptability to complexities, such as mismatches due to part fit-up. Recent advances in automation have enabled the use of industrial robots for complex tasks that require intelligent decision making, predominantly through sensors. Applications such as TIG welding of aerospace components require tight tolerances and need intelligent decision making capability to accommodate any unexpected variation and to carry out welding of complex geometries. Such decision making procedures must be based on the feedback about the weld profile geometry. In this thesis, a real-time position based closed loop system was developed with a six axis industrial robot (KUKA KR 16) and a laser triangulation based sensor (Micro-Epsilon Scan control 2900-25).
67

Novel methods for 3-D semi-automatic mapping of fracture geometry at exposed rock faces

Feng, Quanhong January 2001 (has links)
To analyse the influence of fractures on hydraulic andmechanical behaviour of fractured rock masses, it is essentialto characterise fracture geometry at exposed rock faces. Thisthesis describes three semi-automatic methods for measuring andquantifying geometrical parameters of fractures, and aims tooffer a novel approach to the traditional mapping methods. Three techniques, i.e. geodetic total station, close-rangephotogrammetry and 3-D laser scanner, are used in this studyfor measurement of fracture geometry. The advantages of thesetechniques compared with the traditional method are: i)fracture geometry is quantified semi-automatically in threedimensions; ii) fracture measurements are obtained withoutphysically touching the rock face; iii) the accuracy offracture measurements is improved comparing with thetraditional method; iv) both quantitative and spatial analysisof fracture geometry is possible; v) it offers a way todigitally record the rock surface in three dimensions and invisual format as a database for other applications. The common approach for fracture mapping by using the noveltechniques comprises three main steps: i) capturing 3-Dco-ordinates of target points; ii) quantifying geometricalparameters of fractures from the recorded co-ordinates; iii)documenting the results of fracture mapping. The details ofcapturing 3-D co-ordinates of target points are introduced. Anew algorithm is developed for computing orientation offracture planes. A multiple approach for documenting thefracture mapping results is presented. Application of thesetechniques for measuring and quantifying the geometricalparameters of fractures, such as orientation, trace length andsurface roughness, are demonstrated. The presented methods can greatly improve the quality offracture measurements and avoid the drawbacks inherent intraditional methods. However, it can not replace the humancapacity to filter out and interpret the large amount ofgeometrical information displayed on the rock faces. Themethods may offer an assistance to engineers or geologists inobtaining as much information as possible about the geometryand orientation of rock fractures for rock engineeringapplications. <b>Keywords:</b>3-D laser scanner, close-range photogrammetry,engineering geology, fracture geometry, fracture mapping, rockengineering, rock faces, rock mechanics, three-dimension, totalstation.
68

Approaches to Mobile Robot Localization in Indoor Environments

Jensfelt, Patric January 2001 (has links)
QC 20100621
69

An Approach to 3D Building Model Reconstruction from Airborne Laser Scanner Data Using Parameter Space Analysis and Fusion of Primitives / Eine Methode zur Rekonstruktion von 3D Gebäudemodellen aus Flugzeuglaserscannerdaten unter der Verwendung von Parameterräumen und der Fusion von Primitiven

Hofmann, Alexandra 05 August 2005 (has links) (PDF)
Within this work an approach was developed, which utilises airborne laser scanner data in order to generate 3D building models. These 3D building models may be used for technical and environmental planning. The approach has to follow certain requirements such as working automatically and robust and being flexible in use but still practicable. The approach starts with small point clouds containing one building at the time extracted from laser scanner data set by applying a pre-segmentation scheme. The laser scanner point cloud of each building is analysed separately. A 2.5D-Delaunay triangle mesh structure (TIN) is calculated into the laser scanner point cloud. For each triangle the orientation parameters in space (orientation, slope and perpendicular distance to the barycentre of the laser scanner point cloud) are determined and mapped into a parameter space. As buildings are composed of planar features, primitives, triangles representing these features should group in parameter space. A cluster analysis technique is utilised to find and outline these groups/clusters. The clusters found in parameter space represent plane objects in object space. Grouping adjacent triangles in object space - which represent points in parameter space - enables the interpolation of planes in the ALS points that form the triangles. In each cluster point group a plane in object space is interpolated. All planes derived from the data set are intersected with their appropriate neighbours. From this, a roof topology is established, which describes the shape of the roof. This ensures that each plane has knowledge on its direct adjacent neighbours. Walls are added to the intersected roof planes and the virtual 3D building model is presented in a file written in VRML (Virtual Reality Macro Language). Besides developing the 3D building model reconstruction scheme, this research focuses on the geometric reconstruction and the derivation of attributes of 3D building models. The developed method was tested on different data sets obtained from different laser scanner systems. This study will also show, which potential and limits the developed method has when applied to these different data sets. / In der vorliegenden Arbeit wird eine neue Methode zur automatischen Rekonstruktion von 3D Gebäudemodellen aus Flugzeuglaserscannerdaten vorgestellt. Diese 3D Gebäudemodelle können in technischer und landschaftsplanerischer Hinsicht genutzt werden. Bezüglich der zu entwickelnden Methode wurden Regelungen und Bedingungen erstellt, die eine voll automatische und robuste Arbeitsweise sowie eine flexible und praktikable Nutzung gewährleisten sollten. Die entwickelte Methode verwendet Punktwolken, welche mittels einer Vorsegmentierung aus dem gesamten Laserscannerdatensatz extrahiert wurden und jeweils nur ein Gebäude beinhalten. Diese Laserscannerdatenpunktwolken werden separat analysiert. Eine 2,5D-Delaunay-Dreiecksvermaschung (TIN) wird in jede Punktwolke gerechnet. Für jedes Dreieck dieser Vermaschung werden die Lageparameter im Raum (Ausrichtung, Neigungsgrad und senkrechter Abstand der Ebene des Dreiecks zum Schwerpunkt der Punktwolke) bestimmt und in einen Parameterraum aufgetragen. Im Parameterraum bilden diejenigen Dreiecke Gruppen, welche sich im Objektraum auf ebenen Flächen befinden. Mit der Annahme, dass sich ein Gebäude aus ebenen Flächen zusammensetzt, dient die Identifizierung von Clustern im Parameterraum der Detektierung dieser Flächen. Um diese Gruppen/Cluster aufzufinden wurde eine Clusteranalysetechnik genutzt. Über die detektierten Cluster können jene Laserscannerpunkte im Objektraum bestimmt werden, die eine Dachfläche formen. In die Laserscannerpunkte der somit gefundenen Dachflächen werden Ebenen interpoliert. Alle abgeleiteten Ebenen gehen in den entwickelten Rekonstruktionsalgorithmus ein, der eine Topologie zwischen den einzelnen Ebenen aufbaut. Anhand dieser Topologie erhalten die Ebenen ?Kenntnis? über ihre jeweiligen Nachbarn und können miteinander verschnitten werden. Der fertigen Dachgestalt werden Wände zugefügt und das komplette 3D Gebäudemodell wird mittels VRML (Virtual Reality Macro Language) visualisiert. Diese Studie bezieht sich neben der Entwicklung eines Schemas zu automatischen Gebäuderekonstruktion auch auf die Ableitung von Attributen der 3D Gebäudemodellen. Die entwickelte Methode wurde an verschiedenen Flugzeuglaserscannerdatensätzen getestet. Es wird gezeigt, welche Potentiale und Grenzen die entwickelte Methode bei der Bearbeitung dieser verschiedenen Laserscannerdatensätze hat.
70

Novel methods for 3-D semi-automatic mapping of fracture geometry at exposed rock faces

Feng, Quanhong January 2001 (has links)
<p>To analyse the influence of fractures on hydraulic andmechanical behaviour of fractured rock masses, it is essentialto characterise fracture geometry at exposed rock faces. Thisthesis describes three semi-automatic methods for measuring andquantifying geometrical parameters of fractures, and aims tooffer a novel approach to the traditional mapping methods.</p><p>Three techniques, i.e. geodetic total station, close-rangephotogrammetry and 3-D laser scanner, are used in this studyfor measurement of fracture geometry. The advantages of thesetechniques compared with the traditional method are: i)fracture geometry is quantified semi-automatically in threedimensions; ii) fracture measurements are obtained withoutphysically touching the rock face; iii) the accuracy offracture measurements is improved comparing with thetraditional method; iv) both quantitative and spatial analysisof fracture geometry is possible; v) it offers a way todigitally record the rock surface in three dimensions and invisual format as a database for other applications.</p><p>The common approach for fracture mapping by using the noveltechniques comprises three main steps: i) capturing 3-Dco-ordinates of target points; ii) quantifying geometricalparameters of fractures from the recorded co-ordinates; iii)documenting the results of fracture mapping. The details ofcapturing 3-D co-ordinates of target points are introduced. Anew algorithm is developed for computing orientation offracture planes. A multiple approach for documenting thefracture mapping results is presented. Application of thesetechniques for measuring and quantifying the geometricalparameters of fractures, such as orientation, trace length andsurface roughness, are demonstrated.</p><p>The presented methods can greatly improve the quality offracture measurements and avoid the drawbacks inherent intraditional methods. However, it can not replace the humancapacity to filter out and interpret the large amount ofgeometrical information displayed on the rock faces. Themethods may offer an assistance to engineers or geologists inobtaining as much information as possible about the geometryand orientation of rock fractures for rock engineeringapplications.</p><p><b>Keywords:</b>3-D laser scanner, close-range photogrammetry,engineering geology, fracture geometry, fracture mapping, rockengineering, rock faces, rock mechanics, three-dimension, totalstation.</p>

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