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Towards operational marker-free registration of terrestrial lidar data in forests / Jean-François Tremblay in ISPRS Journal of photogrammetry and remote sensing, vol 146 (December 2018)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 146 (December 2018) . - pp 430 - 435 Titre : Towards operational marker-free registration of terrestrial lidar data in forests Type de document : Article/Communication Auteurs : Jean-François Tremblay, Auteur ; Martin Béland, Auteur Année de publication : 2018 Article en page(s) : pp 430 - 435 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] analyse comparative [Termes IGN] canopée [Termes IGN] cible réfléchissante [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] Etats-Unis [Termes IGN] forêt [Termes IGN] inventaire forestier (techniques et méthodes) [Termes IGN] matrice de covariance [Termes IGN] modèle numérique de terrain [Termes IGN] Québec (Canada) [Termes IGN] semis de points Résumé : (auteur) Terrestrial laser scanning (TLS) often makes use of multiple scans in forests to allow for a complete view of a given area. Combining measurements from multiple locations requires accurate co-registration of the scans to a common reference coordinate system, which currently relies on markers, an often cumbersome process in forests. Existing algorithms for achieving marker-free registration of TLS scans in forests promise to significantly decrease field work time, but are not yet operational and their results have not been validated against traditional methods. Here we present a new implementation of an existing approach which runs in parallel mode and is able to process TLS data acquired over large forest areas. To validate our algorithm, point cloud registration matrices (translation and rotation) derived from our algorithm were compared to those obtained using reflective markers in multiple forest types. The results show that our approach can be used operationally in forests with relatively clear understory, and it provides accuracy similar to that obtained from using reflective markers. Furthermore, we identified factors that can lead to this approach falling short of providing acceptable results in terms of accuracy. Numéro de notice : A2018-542 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2018.10.011 Date de publication en ligne : 02/11/2018 En ligne : https://doi.org/10.1016/j.isprsjprs.2018.10.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91566 [article]

Exemplaires(3)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-2018131	RAB	Revue	Centre de documentation	En réserve L003	Disponible
081-2018133	DEP-EXM	Revue	LASTIG	Dépôt en unité	Exclu du prêt
081-2018132	DEP-EAF	Revue	Nancy	Dépôt en unité	Exclu du prêt

Eccentricity in images of circular and spherical targets and its impact on spatial intersection / Thomas Luhmann in Photogrammetric record, vol 29 n° 148 (December 2014 - February 2015)  

Public [article]  inPhotogrammetric record > vol 29 n° 148 (December 2014 - February 2015) . - pp 417– 433 Titre : Eccentricity in images of circular and spherical targets and its impact on spatial intersection Type de document : Article/Communication Auteurs : Thomas Luhmann, Auteur Année de publication : 2014 Article en page(s) : pp 417– 433 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] cible réfléchissante [Termes IGN] déformation géométrique [Termes IGN] espace image [Termes IGN] modèle géométrique de prise de vue [Termes IGN] modélisation 3D [Termes IGN] projection perspective Résumé : (Auteur) A behaviour of perspective projection which causes eccentricity in the image measurement of circular and spherical targets is discussed. While it is commonly known that flat circular targets can have a significant displacement of the elliptical image centre with respect to the true circle centre, it can also be shown that a similar effect also exists for spherical targets. Both types of target images exhibit elliptical characteristics. If measurement methods such as best-fitting ellipses are used to detect the target, the calculated ellipse centre does not correspond to the desired target centre in 3D space. This paper firstly discusses the use and measurement of circular and spherical targets. It then describes the geometrical projection model in order to demonstrate the eccentricity in image space which, based on numerical simulations, is further quantified and investigated. Finally, the resulting effect in 3D space is estimated for stereo- and multi-image intersections. It is shown that the eccentricity is larger than usually assumed, and must be compensated for in high-accuracy applications. Furthermore, spherical targets do not display better results than circular targets. Numéro de notice : A2014-648 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12084 Date de publication en ligne : 16/12/2014 En ligne : https://doi.org/10.1111/phor.12084 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75094 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
106-2014041	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Multi-view 3D circular target reconstruction with uncertainty analysis / Bahman Soheilian in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol II-3 (September 2014)    

Public [article]  inISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences > vol II-3 (September 2014) . - pp 143 - 148 Titre : Multi-view 3D circular target reconstruction with uncertainty analysis Type de document : Article/Communication Auteurs : Bahman Soheilian , Auteur ; Mathieu Brédif , Auteur Année de publication : 2014 Conférence : PCV 2014, ISPRS Technical Commission 3 Symposium Photogrammetric Computer vision 05/09/2014 07/09/2014 Zurich Suisse OA ISPRS Annals Article en page(s) : pp 143 - 148 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] cible réfléchissante [Termes IGN] cône [Termes IGN] incertitude des données [Termes IGN] matrice de covariance [Termes IGN] modèle de Gauss-Helmert [Termes IGN] programmation par contraintes [Termes IGN] propagation d'erreur [Termes IGN] reconstruction 3D Résumé : (auteur) The paper presents an algorithm for reconstruction of 3D circle from its apparition in n images. It supposes that camera poses are known up to an uncertainty. They will be considered as observations and will be refined during the reconstruction process. First, circle apparitions will be estimated in every individual image from a set of 2D points using a constrained optimization. Uncertainty of 2D points are propagated in 2D ellipse estimation and leads to covariance matrix of ellipse parameters. In 3D reconstruction process ellipse and camera pose parameters are considered as observations with known covariances. A minimal parametrization of 3D circle enables to model the projection of circle in image without any constraint. The reconstruction is performed by minimizing the length of observation residuals vector in a non linear Gauss-Helmert model. The output consists in parameters of the corresponding circle in 3D and their covariances. The results are presented on simulated data. Numéro de notice : A2014-774 Affiliation des auteurs : LASTIG MATIS (2012-2019) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/isprsannals-II-3-143-2014 Date de publication en ligne : 07/09/2014 En ligne : http://dx.doi.org/10.5194/isprsannals-II-3-143-2014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78722 [article]

Documents numériques

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Assessing lidar accuracy with hexagonal retro-reflective targets / Roberto Canavosio-Zuzelski in Photogrammetric Engineering & Remote Sensing, PERS, vol 79 n° 7 (July 2013)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 79 n° 7 (July 2013) . - pp 663 - 670 Titre : Assessing lidar accuracy with hexagonal retro-reflective targets Type de document : Article/Communication Auteurs : Roberto Canavosio-Zuzelski, Auteur ; James Hogarty, Auteur ; Craig Rodarmel, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 663 - 670 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] analyse comparative [Termes IGN] cible réfléchissante [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] instabilité du vecteur (télédétection) [Termes IGN] Lidar [Termes IGN] ligne de visée [Termes IGN] points homologues [Termes IGN] précision du positionnement Résumé : (Auteur) Airborne lidar systems have the potential to produce extremely accurate terrain information at high spatial densities. However, to meet stringent accuracy requirements and minimize systematic errors, proper calibration of the lidar system is required. "Boresighting" is a technique used to correct for some of these systematic errors and improve the spatial alignment of lidar passes. One challenge with boresighting is the mensuration accuracy to which a known point can be located in overlapping low density lidar strips. To address this issue, a raised Hexagonal Retro-Reflective Lidar ground Target (hrrt) is introduced. The target was optimized for precise mensuration at low point densities. The mensuration model is based on a least squares hexagon fitting approach and is proven to produce mensuration accuracies of 5 cm horizontal and 4 cm vertical (1-sigma) at ~2 pts/m2. To demonstrate a practical application, the hrrt's are used as tie points in a rigorous boresight adjustment to compute lidar strip misalignment parameters (roll, pitch, heading, and range bias). The adjustment results show that accurate boresight parameters are recovered along with their associated uncertainties. Numéro de notice : A2013-395 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.79.7.663 En ligne : https://doi.org/10.14358/PERS.79.7.663 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32533 [article]