1,720,955 research outputs found
Contribution to mobile mapping : developpement and caracterisation of a terrestrial laser scanner-based system
No full textLa cartographie mobile est un sujet qui se démocratise et gagne en maturité avec la demande croissante des données tridimensionnelles urbaines et périurbaines. La présente thèse aborde la conception d’un système de cartographie mobile terrestre à faible coût avec la particularité d’avoir adapté un scanner laser terrestre pour une utilisation en mode mobile à faible vitesse. Notre objectif n’est pas de rivaliser en termes de performances avec les systèmes commerciaux mais plutôt de s’approprier les compétences scientifiques et technologiques qui permettront de proposer des solutions dans le domaine de cartographie mobile. Les opérations préalables à la mise en route du système, tel que la synchronisation et l’étalonnage sont exposées. Puis, des méthodes basées sur l’ajustement des modèles polynomiaux sont développées pour convenir aux différents trajets parcourus. Les données issues des différents capteurs (GPS/AHRS/TLS) sont testées et filtrées avant de les intégrer dans l’équation de géoréférencement direct. Il en résulte un nuage de points corrigé. Une étude exhaustive sur l’effet des erreurs de chaque capteur sur le nuage de points résultant est établie. La précision théorique est confrontée avec des jeux des données de référence pour valider l’analyse des erreurs.
Un appareil photo numérique calibré est intégré dans notre système en tant que capteur de navigation. Une solution photogrammétrique est proposée pour améliorer la précision de la trajectométrie préalablement calculée par l’intégration des données GPS/AHRS. Pour conclure la thèse, une ouverture vers la modélisation géométrique est proposée pour exploiter la géométrie et la précision des données laser terrestres fournies par le système. Le prototype développé permet de fournir des nuages de points d’une précision de l’ordre de 10 à 15cm à une distance moyenne de 20 m.Mobile mapping technology has been developing with the growing demand of three-dimensional urban and peri-urban data. This thesis approach is based on the design of a low cost terrestrial mobile mapping system with the adaptation of a Terrestrial Laser Scanner for low dynamics. Our goal is not to compete in performance with commercial systems but rather to appropriate scientific and technological skills which will help in proposing solutions in the field of mobile mapping. Necessary operational settings, such as synchronization and calibration are explained. Then, some methods based on the adjustment of polynomial models are developed according to the traveled paths. Data from various sensors (GPS/ AHRS/TLS) are filtered and tested before their integration by direct georeferencing equation in order to produce a correct point cloud. A comprehensive study on the influence of errors of each sensor on the resulting point cloud is established. The theoretical precision is compared with reference data in order to validate the error analyze. A digital calibrated camera is integrated in the system as a navigation sensor. A photogrammetric solution is proposed to improve the accuracy of the orientation and the position calculated by integrating GPS/ AHRS. At the end of this thesis, an approach towards automatic modeling is proposed to make use of the geometry and precision provided by the system. The designed prototype supplies point clouds whose precision is about 10 to15 cm at the average distance of 20 m
lCL: Iterative closest line A novel point cloud registration algorithm based on linear features
Get PDFThe problem of matching 3D TLS point clouds is a necessary stage which precedes any kind of modeling in order to perfect the object’s geometry and to control its accuracy. It has been studied extensively in many graphical and image-processing domains. However there is a lack of an adaptive study of this problem in the domain of laser scanning for architectural and urban purposes. Hence, our study aims to summarize the existing methods of point clouds registration.
We introduce a line-based matching method which is the so-called ICL (Iterative Closest Line). Some line extraction methods required by the ICL algorithm are also presented. We compare our method to the ICP (Iterative Closest Point) one as well, which is mostly applied in the domain of point cloud and range image registration. Our method is intended to handle the special case where both of the point clouds were obtained by means of as-built topographic terrestrial laser scanner, which means that they are georeferenced and to be affined by the co-registration
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
