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Mapping with small UAS: A point cloud accuracy assessment / Charles K. Toth in Journal of applied geodesy, vol 9 n° 4 (December 2015)  

Public [article]  inJournal of applied geodesy > vol 9 n° 4 (December 2015) . - pp 213 - 226 Titre : Mapping with small UAS: A point cloud accuracy assessment Type de document : Article/Communication Auteurs : Charles K. Toth, Auteur ; Grzegorz Jóźków, Auteur ; Dorota A. Grejner-Brzezinska, Auteur Année de publication : 2015 Article en page(s) : pp 213 - 226 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] caractérisation [Termes descripteurs IGN] drone [Termes descripteurs IGN] géoréférencement direct [Termes descripteurs IGN] image optique [Termes descripteurs IGN] qualité des données [Termes descripteurs IGN] semis de points Résumé : (auteur) Interest in using inexpensive Unmanned Aerial System (UAS) technology for topographic mapping has recently significantly increased. Small UAS platforms equipped with consumer grade cameras can easily acquire high-resolution aerial imagery allowing for dense point cloud generation, followed by surface model creation and orthophoto production. In contrast to conventional airborne mapping systems, UAS has limited ground coverage due to low flying height and limited flying time, yet it offers an attractive alternative to high performance airborne systems, as the cost of the sensors and platform, and the flight logistics, is relatively low. In addition, UAS is better suited for small area data acquisitions and to acquire data in difficult to access areas, such as urban canyons or densely built-up environments. The main question with respect to the use of UAS is whether the inexpensive consumer sensors installed in UAS platforms can provide the geospatial data quality comparable to that provided by conventional systems. This study aims at the performance evaluation of the current practice of UAS-based topographic mapping by reviewing the practical aspects of sensor configuration, georeferencing and point cloud generation, including comparisons between sensor types and processing tools. The main objective is to provide accuracy characterization and practical information for selecting and using UAS solutions in general mapping applications. The analysis is based on statistical evaluation as well as visual examination of experimental data acquired by a Bergen octocopter with three different image sensor configurations, including a GoPro HERO3+ Black Edition, a Nikon D800 DSLR and a Velodyne HDL-32. In addition, georeferencing data of varying quality were acquired and evaluated. The optical imagery was processed by using three commercial point cloud generation tools. Comparing point clouds created by active and passive sensors by using different quality sensors, and finally, by different commercial software tools, provides essential information for the performance validation of UAS technology. Numéro de notice : A2015--010 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article En ligne : http://dx.doi.org/10.1515/jag-2015-0017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80762 [article]

Development, calibration and evaluation of a portable and direct georeferenced laser scanning system for kinematic 3D mapping / Erik Heinz in Journal of applied geodesy, vol 9 n° 4 (December 2015)  

Public [article]  inJournal of applied geodesy > vol 9 n° 4 (December 2015) . - pp 227 - 243 Titre : Development, calibration and evaluation of a portable and direct georeferenced laser scanning system for kinematic 3D mapping Type de document : Article/Communication Auteurs : Erik Heinz, Auteur ; Christian Eling, Auteur ; Markus Wieland, Auteur ; Lasse Klingbeil, Auteur ; Heiner Kuhlmann, Auteur Année de publication : 2015 Article en page(s) : pp 227 - 243 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes descripteurs IGN] étalonnage d'instrument [Termes descripteurs IGN] géoréférencement direct [Termes descripteurs IGN] système de numérisation mobile [Termes descripteurs IGN] télémètre laser [Termes descripteurs IGN] variance Résumé : (auteur) In recent years, kinematic laser scanning has become increasingly popular because it offers many benefits compared to static laser scanning. The advantages include both saving of time in the georeferencing and a more favorable scanning geometry. Often mobile laser scanning systems are installed on wheeled platforms, which may not reach all parts of the object. Hence, there is an interest in the development of portable systems, which remain operational even in inaccessible areas. The development of such a portable laser scanning system is presented in this paper. It consists of a lightweight direct georeferencing unit for the position and attitude determination and a small low-cost 2D laser scanner. This setup provides advantages over existing portable systems that employ heavy and expensive 3D laser scanners in a profiling mode. A special emphasis is placed on the system calibration, i. e. the determination of the transformation between the coordinate frames of the direct georeferencing unit and the 2D laser scanner. To this end, a calibration field is used, which consists of differently orientated georeferenced planar surfaces, leading to estimates for the lever arms and boresight angles with an accuracy of mm and one-tenth of a degree. Finally, point clouds of the mobile laser scanning system are compared with georeferenced point clouds of a high-precision 3D laser scanner. Accordingly, the accuracy of the system is in the order of cm to dm. This is in good agreement with the expected accuracy, which has been derived from the error propagation of previously estimated variance components. Numéro de notice : A2015--011 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article En ligne : http://dx.doi.org/ 10.1515/jag-2015-0011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80763 [article]

Ubiquitous user localization in LBS : The need for implementing ethical thinking in our research field / Guenther Retscher in Journal of applied geodesy, vol 9 n° 4 (December 2015)  

Public [article]  inJournal of applied geodesy > vol 9 n° 4 (December 2015) . - pp 264 - 278 Titre : Ubiquitous user localization in LBS : The need for implementing ethical thinking in our research field Type de document : Article/Communication Auteurs : Guenther Retscher, Auteur ; Franz Obex, Auteur Année de publication : 2015 Article en page(s) : pp 264 - 278 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] application informatique [Termes descripteurs IGN] éthique [Termes descripteurs IGN] géopositionnement [Termes descripteurs IGN] informatique ubiquitaire [Termes descripteurs IGN] protection de la vie privée [Termes descripteurs IGN] service fondé sur la position Résumé : (auteur) Location-based Services (LBS) influence nowadays every individual’s life due to the emerging market penetration of smartphones and other mobile devices. For smartphone Apps localization technologies are developed ranging from GNSS beyond to other alternative ubiquitous positioning methods as well as the use of the in-built inertial sensors, such as accelerometers, gyroscopes, magnetometer, barometer, etc. Moreover, signals-of-opportunity which are not intended for positioning at the first sight but are receivable in many environments such as in buildings and public spaces are more and more utilized for positioning and navigation. The use of Wi-Fi (Wireless Fidelity) is a typical example. These technologies, however, have become very powerful tools as the enable to track an individual or even a group of users. Most technical researchers imply that it is mainly about further enhancing technologies and algorithms including the development of new advanced Apps to improve personal navigation and to deliver location oriented information just in time to a single LBS user or group of users. The authors claim that there is a need that ethical and political issues have to be addressed within our research community from the very beginning. Although there is a lot of research going on in developing algorithms to keep ones data and LBS search request in private, researchers can no longer keep their credibility without cooperating with ethical experts or an ethical committee. In a study called InKoPoMoVer (Cooperative Positioning for Real-time User Assistance and Guidance at Multi-modal Public Transit Junctions) a cooperation with social scientists was initiated for the first time at the Vienna University of Technology, Austria, in this context. The major aims of this study in relation to ethical questions are addressed in this paper. Numéro de notice : A2015--012 Affiliation des auteurs : non IGN Thématique : INFORMATIQUE/POSITIONNEMENT Nature : Article En ligne : http://dx.doi.org/10.1515/jag-2015-0015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80764 [article]