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Optimising drone flight planning for measuring horticultural tree crop structure / Yu-Hsuan Tu in ISPRS Journal of photogrammetry and remote sensing, vol 160 (February 2020)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 160 (February 2020) . - pp 83 - 96 Titre : Optimising drone flight planning for measuring horticultural tree crop structure Type de document : Article/Communication Auteurs : Yu-Hsuan Tu, Auteur ; Stuart Phinn, Auteur ; Kasper Johansen, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 83 - 96 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes descripteurs IGN] correction d'image [Termes descripteurs IGN] détection d'arbres [Termes descripteurs IGN] distorsion d'image [Termes descripteurs IGN] étalonnage de chambre métrique [Termes descripteurs IGN] horticulture [Termes descripteurs IGN] image de drone [Termes descripteurs IGN] MicMac [Termes descripteurs IGN] obturateur [Termes descripteurs IGN] photogrammétrie aérienne [Termes descripteurs IGN] plan de vol [Termes descripteurs IGN] point d'appui [Termes descripteurs IGN] qualité d'image [Termes descripteurs IGN] Queensland (Australie) Résumé : (Auteur) In recent times, multi-spectral drone imagery has proved to be a useful tool for measuring tree crop canopy structure. In this context, establishing the most appropriate flight planning variable settings is an essential consideration due to their controls on the quality of the imagery and derived maps of tree and crop biophysical properties. During flight planning, variables including flight altitude, image overlap, flying direction, flying speed and solar elevation, require careful consideration in order to produce the most suitable drone imagery. Previous studies have assessed the influence of individual variables on image quality, but the interaction of multiple variables has yet to be examined. This study assesses the influence of several flight variables on measures of data quality in each processing step, i.e. photo alignment, point cloud densification, 3D model building, and ortho-mosaicking. The analysis produced a drone flight planning and image processing workflow that delivers accurate measurements of tree crops, including the tie point quality, densified point cloud density, and the measurement accuracy of height and plant projective cover derived from individual trees within a commercial avocado orchard. Results showed that flying along the hedgerow, at high solar elevation and with low image pitch angles improved the data quality. Optimal flying speed needs to be set to achieve the required forward overlap. The impacts of each image acquisition variable are discussed in detail and protocols for flight planning optimisation for three scenarios with different drone settings are suggested. Establishing protocols that deliver optimal image acquisitions for the collection of drone data over horticultural tree crops, will create greater confidence in the accuracy of subsequent algorithms and resultant maps of biophysical properties. Numéro de notice : A2020-044 Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2019.12.006 date de publication en ligne : 18/12/2019 En ligne : https://doi.org/10.1016/j.isprsjprs.2019.12.006 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94524 [article]

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A two-step approach for the correction of rolling shutter distortion in UAV photogrammetry / Yilin Zhou in ISPRS Journal of photogrammetry and remote sensing, vol 160 (February 2020)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 160 (February 2020) . - pp 51 - 66 Titre : A two-step approach for the correction of rolling shutter distortion in UAV photogrammetry Type de document : Article/Communication Auteurs : Yilin Zhou, Auteur ; Mehdi Daakir, Auteur ; Ewelina Rupnik , Auteur ; Marc Pierrot-Deseilligny , Auteur Année de publication : 2020 Article en page(s) : pp 51 - 66 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes descripteurs IGN] capteur aérien [Termes descripteurs IGN] compensation par faisceaux [Termes descripteurs IGN] correction [Termes descripteurs IGN] création de zone intermédiaire [Termes descripteurs IGN] distorsion d'image [Termes descripteurs IGN] étalonnage en vol [Termes descripteurs IGN] image de drone [Termes descripteurs IGN] MicMac [Termes descripteurs IGN] obturateur [Termes descripteurs IGN] photogrammétrie aérienne Résumé : (Auteur) The use of consumer grade unmanned aerial vehicles (UAV) is becoming more and more ubiquitous in photogrammetric applications. A large proportion of consumer grade UAVs are equipped with CMOS image sensor and rolling shutter. When imaging with a rolling shutter camera, the image sensor is exposed line by line, which can introduce additional distortions in image space since the UAV navigates at a relatively high speed during aerial acquisitions. In this paper, we propose (1) an approach to calibrate the readout time of rolling shutter camera, (2) a two-step method to correct the image distortion introduced by this effect. The two-step method makes assumption that during exposure, the change of camera orientation is negligible with respect to the change of camera position, which is often the case when camera is fixed on a stabilized mount. Firstly, the camera velocity is estimated from the results of an initial bundle block adjustment; then, one camera pose per scan-line of the image sensor is recovered and image observations are corrected. To evaluate the performance of the proposed method, four datasets of block and corridor configurations are acquired with the DJI Mavic 2 Pro and its original Hasselbald L1D-20c camera. The proposed method is implemented in MicMac, a free, open-source photogrammetric software; comparisons are carried out with other two mainstream software, AgiSoft MetaShape and Pix4D, which also have the functionality of rolling shutter effect correction. For block configuration datasets, the three software give comparable results. AgiSoft Metashape and Pix4D are sensitive to the flight configuration and encounter difficulties when processing datasets in corridor configurations. The proposed method shows good robustness both in block and corridor configurations, and is the only method that works in corridor configuration. After the application of the rolling shutter effect correction, the 3D accuracy is improved by 30–60% in block configuration and 15–25% in corridor configuration. A further improvement can be expected if a precise dating of image is available or if the camera positions can be directly extracted from GNSS data. Numéro de notice : A2020-018 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2019.11.020 date de publication en ligne : 16/12/2019 En ligne : https://doi.org/10.1016/j.isprsjprs.2019.11.020 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94456 [article]

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Métrologie 100% automatique par photogrammétrie aéroportée légère et GPS de précision permanent et embarqué, application au suivi de digues / Yilin Zhou (2019)

Public Titre : Métrologie 100% automatique par photogrammétrie aéroportée légère et GPS de précision permanent et embarqué, application au suivi de digues Type de document : Thèse/HDR Auteurs : Yilin Zhou, Auteur ; Marc Pierrot-Deseilligny , Directeur de thèse Editeur : Champs/Marne : Université Paris-Est Marne-la-Vallée UPEM Année de publication : 2019 Importance : 181 p. Format : 21 x 30 cm Note générale : bibliographie Thèse de Doctorat de l'Université Paris-Est, Spécialité : Sciences et Technologies de l'Information Géographique Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes descripteurs IGN] angle nadiral [Termes descripteurs IGN] digue [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] effet thermique [Termes descripteurs IGN] étalonnage de chambre métrique [Termes descripteurs IGN] image aérienne [Termes descripteurs IGN] image aérienne oblique [Termes descripteurs IGN] image de drone [Termes descripteurs IGN] modélisation 3D [Termes descripteurs IGN] obturateur [Termes descripteurs IGN] photogrammétrie métrologique [Termes descripteurs IGN] point d'appui [Termes descripteurs IGN] réseau fluvial Résumé : (auteur) The development of unmanned aerial vehicle (UAV) platform makes it nowadays a valuable source of data for inspection, surveillance, mapping and 3D modeling issues. UAV photogrammetry opens various new applications in close-range aerial domain and introduces a low-cost alternative to classical manned vehicle photogrammetry. Corridor mapping, one of the fields with substantial importance for UAV photo-grarnmetry, is largely demanded in the surveillance and management of infrastructure assets — highways, railways, waterways and pipelines. Due to the special geometry of the scene, corridor mapping is one case that needs taking precautions. Errors accumu-late easily on the longer dimension of the scene and a bowl effect is often observed; the flatness of the scene introduces strong correlations between parameters to be determi-ned, these two factors together, make it more difficult to obtain high accuracy results in corridor configuration than in classical ones. This thesis is a research project initiated by the CNR, a river concessionary, which has the responsibility of the maintenance and surveillance of its hydraulic facilities, more particularly the dikes. The objective is to apply UAV photogrammetry, which is faster, cheaper and offers a 3D dense reconstruction of the scene, to the monitoring of dikes. While maintaining a high surveying accuracy, a reduced field work, i.e. the number of ground control points (GCPs) is expected. In the first place, simulations are carried out to gain an insight of several problems of corridor mapping that impact the final accuracy. Then, thorough investigations are conducted on three aspects that interest us the most. The first study focuses on the aerial acquisition geometry, discussions are given on the influence of oblique images, nadir images of different flight heights as well as the possibility of an in-flight camera calibration and its application on unfavourable acquisition geometry. The second study aims to improve the acquisition performance for high-end metric cameras. The image deformation introduced by camera temperature variation is investigated and modelled. A method for the correction of this thermal effect is proposed, its performance is eva-luated on both terrestrial and aerial datasets of corridor configuration. The last study interests in the rolling shutter effect for consumer-grade cameras, which is commonly seen in UAV platforms on the market. Two methods are presented to calibrate the camera readout time, a property that is often not given by camera manufacturers. A two-step method is proposed for the correction of rolling shutter effect, its performance is evaluated in both block and corridor configurations. Note de contenu : 1- Introduction en français 2- Introduction 3- State of the art 4- Simulation and analysis 5- Study of aerial acquisition geometry 6- Study of thermal effect 7- Study of rolling shutter effect 8- Conclusion and perspective Numéro de notice : 25522 Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Sciences et Technologies de l'Information Géographique : Paris-Est : 2019 Organisme de stage : Lastig (IGN) Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94383

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Hemispherical sky radiance measurement using a fish-eye camera / Manchun Lei (2018)    

Public contenu dans Conférence Française de Photogrammétrie et de Télédétection, 25 - 28 juin 2018, Marne-la-Vallée / Clément Mallet (2018)   Titre : Hemispherical sky radiance measurement using a fish-eye camera Type de document : Article/Communication Auteurs : Manchun Lei , Auteur ; Ewelina Rupnik , Auteur ; Jean-Pierre Piasco, Auteur ; Lâmân Lelégard , Auteur ; Olivier Martin , Auteur ; Jean Philippe Souchon, Auteur ; Christophe Meynard, Auteur Congrès : CFPT 2018, Conférence Française de Photogrammétrie et de Télédétection (25 - 28 juin 2018; Champs/Marne, Marne-la-Vallée, France), Commanditaire Editeur : Saint-Mandé : Institut national de l'information géographique et forestière - IGN Année de publication : 2018 Projets : 1-Pas de projet / Importance : 3 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes descripteurs IGN] chambre de prise de vue numérique [Termes descripteurs IGN] étalonnage géométrique [Termes descripteurs IGN] étalonnage radiométrique [Termes descripteurs IGN] image hémisphérique [Termes descripteurs IGN] image numérique [Termes descripteurs IGN] objectif grand angulaire Résumé : (auteur) The objective of this work is to perform sky radiance angular distribution measurement using a fish-eye camera. The imaging system provides hemispherical high dynamic range (HDR) sky radiance images at high spatial resolution and radiometric sensibility, which can be used as complementary information for urban remote sensing application such as shaded surface reflectance retrieval. This communication presents the instrument, the radiometric and geometric calibration in detail. Numéro de notice : C2018-012 Thématique : IMAGERIE Nature : Poster nature-HAL : Poster-avec-CL DOI : sans date de publication en ligne : 25/06/2018 En ligne : https://rfiap2018.ign.fr/sites/default/files/ARTICLES/CFPT2018/Posters/CFPT2018_ [...] Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90383

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Experiences with the QDaedalus system for astrogeodetic determination of deflections of the vertical / Markus Hauk in Survey review, vol 49 n° 355 (October 2017)  

Public [article]  inSurvey review > vol 49 n° 355 (October 2017) . - pp 294 - 301 Titre : Experiences with the QDaedalus system for astrogeodetic determination of deflections of the vertical Type de document : Article/Communication Auteurs : Markus Hauk, Auteur ; C. Hirt, Auteur ; C. Ackermann, Auteur Année de publication : 2017 Article en page(s) : pp 294 - 301 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] astronomie géodésique [Termes descripteurs IGN] Bavière (Allemagne) [Termes descripteurs IGN] chambre zénithale [Termes descripteurs IGN] champ de pesanteur local [Termes descripteurs IGN] détecteur à transfert de charge [Termes descripteurs IGN] déviation de la verticale [Termes descripteurs IGN] tachéomètre Résumé : (Auteur) This paper explores the astrogeodetic deflection of the vertical (VD) determination with a light-weight tachymeter-based measurement system called ‘QDaedalus’ developed at ETH Zurich. A description of the relevant components of the system is given to show the set-up and operation. The measuring process including CCD-tachymeter calibration and the astronomical data processing are summarised. The paper then analyses the achievable accuracy of VDs based on new measurement data acquired in Bavaria over several nights. Our measurements were executed atop a pillar on the roof of the TUM and at six stations in the Bavarian Alps (Estergebirge) with highly accurate VDs from previous digital zenith camera measurements available. Our comparisons indicate an accuracy level of 0.15–0.20 arc-seconds for VDs measured with QDaedalus. As a conclusion, our results show that the QDaedalus system is a promising sensor for accurate local astronomical gravity field surveys when a zenith camera is not available. Numéro de notice : A2017-552 Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1171960 En ligne : https://doi.org/10.1080/00396265.2016.1171960 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86613 [article]

Automatic measurement of control points for aerial image orientation / Adilson Berveglieri in Photogrammetric record, vol 32 n° 158 (June - july 2017)  

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Improved wide-angle, fisheye and omnidirectional camera calibration / Steffen Urban in ISPRS Journal of photogrammetry and remote sensing, vol 108 (October 2015)  

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Accuracy analysis of a dual camera system with an asymmetric photogrammetric configuration / Bo Wu in Photogrammetric Engineering & Remote Sensing, PERS, vol 81 n° 3 (March 2015)

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Métrologie par photogrammétrie aéroportée légère : application au suivi d'évolution de digues / Vincent Tournadre (2015)  

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Du photon au pixel / Henri Maître (2015)

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Assessing the potential for leaf-off LiDAR data to model canopy closure in temperate deciduous forests / Jason R. Parent in ISPRS Journal of photogrammetry and remote sensing, vol 95 (September 2014)

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Projets créatifs avec Raspberry Pi / Donald Norris (2014)

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Calibration de caméra par acquisition de type panoramique / Bertrand Cannelle in Revue Française de Photogrammétrie et de Télédétection, n° 194 (Mai 2011)

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Éléments de technologie pour comprendre la photographie / Michel De Ferrières (2011)

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