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Quality assessment of geometric façade models reconstructed from TLS data / Tania Landes in Photogrammetric record, vol 27 n° 138 (June - August 2012)  

Public [article]  inPhotogrammetric record > vol 27 n° 138 (June - August 2012) . - pp 137 - 154 Titre : Quality assessment of geometric façade models reconstructed from TLS data Type de document : Article/Communication Auteurs : Tania Landes, Auteur ; Hakim Boulaassal, Auteur ; Pierre Grussenmeyer, Auteur Année de publication : 2012 Article en page(s) : pp 137 - 154 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] évaluation des données [Termes IGN] façade [Termes IGN] indicateur de qualité [Termes IGN] modèle 3D de l'espace urbain [Termes IGN] modèle géométrique du bâti [Termes IGN] qualité des données [Termes IGN] reconstruction 3D du bâti [Termes IGN] segmentation Résumé : (Auteur) Terrestrial laser scanner (TLS) data plays an important role in 3D modelling of urban scenes. Much research is carried out in the fields of pre-processing, segmentation and geometric reconstruction of laser data of building façades. However, the quality of 3D models obtained from this data is rarely assessed. This paper proposes a qualitative and quantitative assessment approach to evaluate the quality of 3D models of façades constructed with TLS data. Only segmentation and reconstruction operations are considered in this paper, because they cover the main steps in the 3D modelling process. Since every processing step produces an intermediate result, each one must be analysed and compared with an appropriate reference model. A new approach has been conceived to evaluate the precision of the segmentation results. It is based on the calculation of Boolean operators enabling the comparison of planar clusters produced by the segmentation. To evaluate the vector models resulting from the reconstruction step, a method based on quality indices is proposed. It is adapted not only for precision but also for accuracy calculations. The results show that the quality assessment approach is coherent and, moreover, easy to apply. Numéro de notice : A2012-303 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00674.x Date de publication en ligne : 10/04/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00674.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31749 [article]

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Modelling and compensating internal light scattering in time of flight range cameras / Wilfiried Karel in Photogrammetric record, vol 27 n° 138 (June - August 2012)  

Public [article]  inPhotogrammetric record > vol 27 n° 138 (June - August 2012) . - pp 155 - 174 Titre : Modelling and compensating internal light scattering in time of flight range cameras Type de document : Article/Communication Auteurs : Wilfiried Karel, Auteur ; Sajid Ghuffar, Auteur ; Norbert Pfeifer, Auteur Année de publication : 2012 Article en page(s) : pp 155 - 174 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] analyse comparative [Termes IGN] étalonnage de chambre métrique [Termes IGN] évaluation des paramètres [Termes IGN] propagation du signal [Termes IGN] temps de propagation Résumé : (Auteur) Time of flight range cameras simultaneously gather object distances for all pixels of a focal plane array by evaluating the round-trip time of an emitted signal. While ranging precisions typically amount to some centimeters, accuracies may be worse by an order of magnitude. Scattering is one of the sources of systematic errors, caused by the spreading of portions of the incident light over the sensor due to multiple reflections between the sensor, lens and optical filter. The present contribution analyses this phenomenon with respect to various capture parameters, with the objective of achieving a better understanding and a validation of assumptions. Subsequently, the authors derive both image space invariant and variant models for scattering, apply them to test scenes, and compare the results to each other and to those of existing methods. Numéro de notice : A2012-304 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00685.x Date de publication en ligne : 20/06/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00685.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31750 [article]

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GPU-based volumetric reconstruction and rendering of trees from multiple images / D. Vock in Photogrammetric record, vol 27 n° 138 (June - August 2012)  

Public [article]  inPhotogrammetric record > vol 27 n° 138 (June - August 2012) . - pp 175 - 194 Titre : GPU-based volumetric reconstruction and rendering of trees from multiple images Type de document : Article/Communication Auteurs : D. Vock, Auteur ; S. Gumhold, Auteur ; M. Spehr, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 175 - 194 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] arbre (flore) [Termes IGN] élément d'orientation externe [Termes IGN] élément d'orientation interne [Termes IGN] modélisation 3D [Termes IGN] reconstruction d'objet [Termes IGN] station graphique [Termes IGN] tomographie Résumé : (Auteur) This paper presents a new hardware-accelerated approach to the volumetric reconstruction of trees from photographs, based on the methods introduced by Reche-Martinez et al. The system applies an adapted computed tomography (CT) procedure that uses a set of oriented photographs with known interior and exterior camera parameters for creating a 3D model of a tree, while requiring considerably fewer images than standard CT. As tomographic reconstructions are complex tasks that result in time-consuming processes for high-resolution volumes, the hitherto existing methods are improved and modified to allow an ideal parallelisation of the computations on graphics hardware. The paper delivers a detailed insight into the complete process of the reconstruction, from the acquisition and preparation of the input data to the implementation of the final system on graphics processing hardware. Numéro de notice : A2012-305 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00683.x Date de publication en ligne : 20/06/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00683.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31751 [article]

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Capturing sail shape in a wind tunnel environment / M. Smith in Photogrammetric record, vol 27 n° 138 (June - August 2012)  

Public [article]  inPhotogrammetric record > vol 27 n° 138 (June - August 2012) . - pp 195 - 209 Titre : Capturing sail shape in a wind tunnel environment Type de document : Article/Communication Auteurs : M. Smith, Auteur ; J. Paton, Auteur ; H. Morvan, Auteur ; N. Korras, Auteur Année de publication : 2012 Article en page(s) : pp 195 - 209 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] étalonnage de chambre métrique [Termes IGN] modèle numérique de surface [Termes IGN] photogrammétrie terrestre [Termes IGN] stéréophotogrammétrie [Termes IGN] test de performance Résumé : (Auteur) Validation is an important part of computer-based numerical modelling and can be very difficult to achieve. Comparisons with results from practical trials are often used; in this research, photogrammetry has proved to be an excellent method of creating a benchmark model from experimental results against which the computer generated numerical model can be compared. The wind tunnel experimental environment is challenging with practical limitations imposed by space and airflow capabilities. There are few documented cases where stereo-photogrammetry has been used in wind tunnel sail modelling and the results from this research have shown it has played a prominent role in validating an innovative method of modelling fluid–structure interaction. This paper presents the photogrammetric work undertaken to validate a fluid–structure interaction (FSI) solution by measuring the shape of a close reaching asymmetric spinnaker in a wind tunnel at The University of Nottingham. There is particular focus on the data capture in the wind tunnel and the photogrammetric analysis. Numéro de notice : A2012-306 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00684.x Date de publication en ligne : 20/06/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00684.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31752 [article]

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Parameterising internal camera geometry with focusing distance / E. Sanz-Ablanedo in Photogrammetric record, vol 27 n° 138 (June - August 2012)  

Public [article]  inPhotogrammetric record > vol 27 n° 138 (June - August 2012) . - pp 210 - 226 Titre : Parameterising internal camera geometry with focusing distance Type de document : Article/Communication Auteurs : E. Sanz-Ablanedo, Auteur ; Jim H. Chandler, Auteur ; R. Wackrow, Auteur Année de publication : 2012 Article en page(s) : pp 210 - 226 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] étalonnage de chambre métrique [Termes IGN] étalonnage géométrique [Termes IGN] longueur focale [Termes IGN] orientation interne [Termes IGN] photogrammétrie terrestre Résumé : (Auteur) A study on the variation of internal camera geometry (principal distance, principal point position and lens distortion parameters) with different focus distances has been conducted. Results demonstrate that variations of parameters are continuous and predictable, allowing a new way to describe internal camera geometry. The classical constant parameters, c, x p , y p , K 1 , K 2 , P 1 and P 2 , are replaced by continuous functions, c(y), x p (y), y p(y), K 1 (y), K 2 (y), P 1 (y) andP 2 (y), where y is a variable describing the focus position. Incorporation of y as a metadata tag (for example, Exif header) of a photograph jointly with a parameterised definition of camera geometry would allow full use of the autofocus camera function; enabling maximum effective depth of field, better match of the plane of focus with the object’s position and higher reliability. Additionally, conducted tests suggest the parameterised definition of internal geometry could help to locate and correct linear dependences between adjusted parameters, potentially improving the precision and accuracy of calibration. Numéro de notice : A2012-307 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00677.x Date de publication en ligne : 20/06/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00677.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31753 [article]

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Exploiting HD camcorders for close-up human movement applications / A. Chong in Photogrammetric record, vol 27 n° 138 (June - August 2012)  

Public [article]  inPhotogrammetric record > vol 27 n° 138 (June - August 2012) . - pp 227 - 237 Titre : Exploiting HD camcorders for close-up human movement applications Type de document : Article/Communication Auteurs : A. Chong, Auteur Année de publication : 2012 Article en page(s) : pp 227 - 237 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie terrestre [Termes IGN] acquisition d'images [Termes IGN] caméra vidéo numérique [Termes IGN] médecine humaine [Termes IGN] santé [Termes IGN] utilisateur Résumé : (Auteur) Lately, the cost of HD video camcorders has decreased greatly and the inclusion of an internal hard disk in many models has eased the bother of downloading video clips from cumbersome tape devices. These factors have increased their potential as 3D recording devices and measurement tools for the health monitoring of patients by practitioners. This investigation determined: (1) the 3D measurement quality of off-the-shelf high definition camcorders for human-movement-related medical applications; (2) the suitability of a low-cost LED synchronisation device for multi-camcorder tracking; and (3) the suitability of these imaging sensors for practitioners. The results show that a four-camcorder system is capable of measuring a 3D distance in a static setting to better than 0·050 mm; it can track a moving calibrated square-wave signal of 0·5 and 1 Hz to better than 0·3 and 0·2 mm, respectively. Using a calibrated scale bar mounted on a moving human leg, the error produced as a result of frame disparity using a low-cost LED frame-synchronising device was under 0·3 mm for a four-, three- and two-camcorder configuration. Numéro de notice : A2012-308 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2012.00673.x Date de publication en ligne : 27/03/2012 En ligne : https://doi.org/10.1111/j.1477-9730.2012.00673.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31754 [article]

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