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Improved GPS-based single-frequency orbit determination for the CYGNSS spacecraft using GipsyX / Alex V. Conrad in Navigation : journal of the Institute of navigation, vol 70 n° 1 (Spring 2023)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 70 n° 1 (Spring 2023) . - n° 565 Titre : Improved GPS-based single-frequency orbit determination for the CYGNSS spacecraft using GipsyX Type de document : Article/Communication Auteurs : Alex V. Conrad, Auteur ; Penina Axelrad, Auteur ; Bruce J. Haines, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 565 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] données GRACE [Termes IGN] étalonnage d'instrument [Termes IGN] mesurage de phase [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] récepteur monofréquence [Termes IGN] trajet multiple Résumé : (auteur) This paper presents methods for the precise orbit determination (POD) of a satellite in the CYGNSS constellation based on available single-frequency GPS code and carrier measurements. The contributions include the development and evaluation of procedures for single-frequency POD with GipsyX, improvement of CYGNSS orbit knowledge, and an assessment of its final accuracy. Ionospheric effects are mitigated using the GRAPHIC processing method, and spacecraft multipath effects are calibrated with an azimuth/elevation-dependent antenna calibration map. The method is demonstrated using comparable data from the GRACE mission, from which we infer the expected accuracy of the CYGNSS results. Processing more than 170 days of data from each mission, a 1σ CYGNSS orbit accuracy of 2.8 cm radial, 2.4 cm cross-track, and 6 cm in-track is demonstrated. We expect that achieving this level of performance will expand the set of future scientific investigations that can be undertaken using satellites equipped with single-frequency GNSS. Numéro de notice : A2023-141 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.565 Date de publication en ligne : 20/10/2022 En ligne : https://doi.org/10.33012/navi.565 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102708 [article]

3D browsing of wide-angle fisheye images under view-dependent perspective correction / Mingyi Huang in Photogrammetric record, vol 37 n° 178 (June 2022)  

Public [article]  inPhotogrammetric record > vol 37 n° 178 (June 2022) . - pp 185 - 207 Titre : 3D browsing of wide-angle fisheye images under view-dependent perspective correction Type de document : Article/Communication Auteurs : Mingyi Huang, Auteur ; Jun Wu, Auteur ; Zhiyong Peng, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 185 - 207 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] classification par réseau neuronal convolutif [Termes IGN] correction d'image [Termes IGN] distorsion d'image [Termes IGN] étalonnage d'instrument [Termes IGN] image hémisphérique [Termes IGN] objectif très grand angulaire [Termes IGN] panorama sphérique [Termes IGN] perspective [Termes IGN] processeur graphique [Termes IGN] projection orthogonale [Termes IGN] projection perspective Résumé : (auteur) This paper presents a novel technique for 3D browsing of wide-angle fisheye images using view-dependent perspective correction (VDPC). First, the fisheye imaging model with interior orientation parameters (IOPs) is established. Thereafter, a VDPC model for wide-angle fisheye images is proposed that adaptively selects correction planes for different areas of the image format. Finally, the wide-angle fisheye image is re-projected to obtain the visual effect of browsing in hemispherical space, using the VDPC model and IOPs of the fisheye camera calibrated using the ideal projection ellipse constraint. The proposed technique is tested on several downloaded internet images with unknown IOPs. Results show that the proposed VDPC model achieves a more uniform perspective correction of fisheye images in different areas, and preserves the detailed information with greater flexibility compared with the traditional perspective projection conversion (PPC) technique. The proposed algorithm generates a corrected image of 512 × 512 pixels resolution at a speed of 58 fps when run on a pure central processing unit (CPU) processor. With an ordinary graphics processing unit (GPU) processor, a corrected image of 1024 × 1024 pixels resolution can be generated at 60 fps. Therefore, smooth 3D visualisation of a fisheye image can be realised on a computer using the proposed algorithm, which may benefit applications such as panorama surveillance, robot navigation, etc. Numéro de notice : A2022-518 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12410 Date de publication en ligne : 10/05/2022 En ligne : https://doi.org/10.1111/phor.12410 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101068 [article]

Calibration of a light hemispherical radiance field imaging system / Manchun Lei in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol V-1-2022 (2022 edition)  

Public [article]  inISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences > vol V-1-2022 (2022 edition) . - pp 195 - 202 Titre : Calibration of a light hemispherical radiance field imaging system Type de document : Article/Communication Auteurs : Manchun Lei , Auteur ; Christian Thom , Auteur ; Christophe Meynard , Auteur ; Jean-Michaël Muller , Auteur Année de publication : 2022 Projets : 1-Pas de projet / Article en page(s) : pp 195 - 202 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] étalonnage géométrique [Termes IGN] étalonnage radiométrique [Termes IGN] image hémisphérique [Termes IGN] modèle géométrique de prise de vue [Termes IGN] radiance [Termes IGN] zone urbaine Résumé : (auteur) A light hemispherical radiance field imaging system based on fish-eye camera was developed for the measurement of the surface incident radiance in an urban environment, which is often affected by radiometric heterogeneity problems. A linear radiometric model and a polynomial fish-eye lens model are used. A temperature-dependent dark level model is proposed to improve the dark correction for high dynamic range photography. This paper describes the calibration procedure for spectral and geometrical radiance field measurements and presents the results of the calibration. The spectral radiometric calibration error is 2.07%, 1.34%, and 0.98% for blue, green, and red bands, respectively. The mean geometrical calibration error is 2.037 pixels. Numéro de notice : A2022-438 Affiliation des auteurs : UGE-LASTIG (2020- ) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/isprs-annals-V-1-2022-195-2022 Date de publication en ligne : 17/05/2022 En ligne : https://doi.org/10.5194/isprs-annals-V-1-2022-195-2022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100750 [article]

Estimating forest attributes in airborne laser scanning based inventory using calibrated predictions from external models / Ana de Lera Garrido in Silva fennica, vol 56 n° 2 (April 2022)  

Public [article]  inSilva fennica > vol 56 n° 2 (April 2022) . - n° 10695 Titre : Estimating forest attributes in airborne laser scanning based inventory using calibrated predictions from external models Type de document : Article/Communication Auteurs : Ana de Lera Garrido, Auteur ; Terje Gobakken, Auteur ; Hans Ole Ørka, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 10695 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] étalonnage [Termes IGN] hauteur des arbres [Termes IGN] inventaire forestier étranger (données) [Termes IGN] modèle de simulation [Termes IGN] modélisation spatio-temporelle [Termes IGN] Norvège [Termes IGN] parcelle forestière [Termes IGN] placette d'échantillonnage [Termes IGN] semis de points [Termes IGN] volume en bois Résumé : (auteur) Forest management inventories assisted by airborne laser scanner data rely on predictive models traditionally constructed and applied based on data from the same area of interest. However, forest attributes can also be predicted using models constructed with data external to where the model is applied, both temporal and geographically. When external models are used, many factors influence the predictions’ accuracy and may cause systematic errors. In this study, volume, stem number, and dominant height were estimated using external model predictions calibrated using a reduced number of up-to-date local field plots or using predictions from reparametrized models. We assessed and compared the performance of three different calibration approaches for both temporally and spatially external models. Each of the three approaches was applied with different numbers of calibration plots in a simulation, and the accuracy was assessed using independent validation data. The primary findings were that local calibration reduced the relative mean difference in 89% of the cases, and the relative root mean squared error in 56% of the cases. Differences between application of temporally or spatially external models were minor, and when the number of local plots was small, calibration approaches based on the observed prediction errors on the up-to-date local field plots were better than using the reparametrized models. The results showed that the estimates resulting from calibrating external models with 20 plots were at the same level of accuracy as those resulting from a new inventory. Numéro de notice : A2022-367 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14214/sf.10695 Date de publication en ligne : 25/04/2022 En ligne : https://doi.org/10.14214/sf.10695 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100589 [article]

Evaluating the 3D integrity of underwater structure from motion workflows / Ian M. Lochhead in Photogrammetric record, vol 37 n° 177 (March 2022)  

Public [article]  inPhotogrammetric record > vol 37 n° 177 (March 2022) . - pp 35 - 60 Titre : Evaluating the 3D integrity of underwater structure from motion workflows Type de document : Article/Communication Auteurs : Ian M. Lochhead, Auteur Année de publication : 2022 Article en page(s) : pp 35 - 60 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] auscultation d'ouvrage [Termes IGN] chaîne de traitement [Termes IGN] étalonnage d'instrument [Termes IGN] fond marin [Termes IGN] image sous-marine [Termes IGN] modélisation 3D [Termes IGN] Pacifique nord [Termes IGN] récif corallien [Termes IGN] semis de points [Termes IGN] semis de points clairsemés [Termes IGN] structure-from-motion Résumé : (auteur) Structure from motion (SfM) is an accessible and non-intrusive method of three-dimensional (3D) data capture popular for tropical coral reef surveying. In the north-east Pacific Ocean, where there are many environmentally sensitive benthic organisms whose morphology and function are equally important, SfM surveys are less commonly studied. Temperate waters pose unique challenges to SfM workflows, which must be systematically unpacked to understand their impact on data quality and veracity. This uncertainty raises broader questions concerning SfM as a spatial data-acquisition and ecological characterisation method in temperate waters, and whether a systematic workflow assessment reveals vital relationships between SfM implementation parameters, 3D data products and their implications for underwater SfM surveys. This paper, the second of two empirical assessments, reports on a series of wet-lab and dryland tests quantifying the impact that temperate waters, underwater cameras, and photograph quantity and configuration have on SfM accuracy. These tests provided crucial accuracy benchmarks informing subsequent field-based surveys and revealed that underwater SfM workflows can generate highly accurate 3D models in temperate waters. Numéro de notice : A2022-253 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : doi.org/10.1111/phor.12399 Date de publication en ligne : 07/03/2022 En ligne : https://doi.org/10.1111/phor.12399 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100216 [article]

Exploiting light directionality for image-based 3D reconstruction of non-collaborative surfaces / Ali Karami in Photogrammetric record, vol 37 n° 177 (March 2022)  

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Validating a new GNSS-based sea level instrument (CalNaGeo) at Senetosa Cape / Pascal Bonnefond in Marine geodesy, vol 45 n° 2 (March 2022)  

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Calibration radiométrique et géométrique d'une caméra fish-eye pour la mesure de l'hémisphère de luminance incidente / Manchun Lei (2022)    

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Multi-frequency quadrifilar helix antennas for cm-accurate GNSS positioning / Lambert Wanninger in Journal of applied geodesy, vol 16 n° 1 (January 2022)  

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Photogrammetric 3D mobile mapping of rail tracks / Philipp Glira in ISPRS Journal of photogrammetry and remote sensing, vol 183 (January 2022)  

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Recursive Gauss-Helmert model with equality constraints applied to the efficient system calibration of a 3D laser scanner / Sören Vogel in Journal of applied geodesy, vol 16 n° 1 (January 2022)  

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UAVs for the environmental sciences / Annette Eltner (2022)  

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Application of a hand-held LiDAR scanner for the urban cadastral detail survey in digitized cadastral area of Taiwan urban city / Shih-Hong Chio in Remote sensing, vol 13 n° 24 (December-2 2021)  

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Semi-automatic reconstruction of object lines using a smartphone’s dual camera / Mohammed Aldelgawy in Photogrammetric record, Vol 36 n° 176 (December 2021)  

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Sentinel-6A precise orbit determination using a combined GPS/Galileo receiver / Oliver Montenbruck in Journal of geodesy, vol 95 n° 10 (October 2021)  

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