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Automated calibration of smartphone cameras for 3D reconstruction of mechanical pipes / Reza Maalek in Photogrammetric record, vol 36 n° 174 (June 2021)  

Public [article]  inPhotogrammetric record > vol 36 n° 174 (June 2021) . - pp 124 - 146 Titre : Automated calibration of smartphone cameras for 3D reconstruction of mechanical pipes Type de document : Article/Communication Auteurs : Reza Maalek, Auteur ; Derek D. Lichti, Auteur Année de publication : 2021 Article en page(s) : pp 124 - 146 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] appariement de formes [Termes IGN] autoétalonnage [Termes IGN] canalisation [Termes IGN] compensation par faisceaux [Termes IGN] ellipse [Termes IGN] étalonnage d'instrument [Termes IGN] reconstruction 3D [Termes IGN] structure-from-motion [Termes IGN] téléphone intelligent [Termes IGN] triangulation Résumé : (auteur) This paper outlines a new framework for the calibration of optical instruments, in particular smartphone cameras, using highly redundant circular black-and-white target fields. New methods were introduced for (i) matching targets between images; (ii) adjusting the systematic eccentricity error of target centres; and (iii) iteratively improving the calibration solution through a free-network self-calibrating bundle adjustment. The proposed method effectively matched circular targets in 270 smartphone images, taken within a calibration laboratory, with robustness to type II errors (false negatives). The proposed eccentricity adjustment, which requires only camera projective matrices from two views, behaved comparably to available closed-form solutions, which require additional a priori object-space target information. Finally, specifically for the case of mobile devices, the calibration parameters obtained using the framework were found to be superior compared to in situ calibration for estimating the 3D reconstructed radius of a mechanical pipe (approximately 45% improvement on average). Numéro de notice : A2021-512 Affiliation des auteurs : non IGN Nature : Article DOI : 10.1111/phor.12364 date de publication en ligne : 06/06/2021 En ligne : https://doi.org/10.1111/phor.12364 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97929 [article]

Georeferencing with self-calibration for airborne full-waveform Lidar data using digital elevation model / Qinghua Li in Photogrammetric Engineering & Remote Sensing, PERS, vol 87 n° 1 (January 2021)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 87 n° 1 (January 2021) . - pp 43 - 52 Titre : Georeferencing with self-calibration for airborne full-waveform Lidar data using digital elevation model Type de document : Article/Communication Auteurs : Qinghua Li, Auteur ; Jie Shan, Auteur Année de publication : 2021 Article en page(s) : pp 43 - 52 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] autoétalonnage [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] étalonnage de capteur (imagerie) [Termes IGN] forme d'onde pleine [Termes IGN] géoréférencement [Termes IGN] modèle géométrique de prise de vue [Termes IGN] modèle numérique de surface [Termes IGN] optimisation (mathématiques) [Termes IGN] point d'appui [Termes IGN] synchronisation Résumé : (Auteur) Precise georeferencing of airborne full-waveform lidar is a complex process. On one hand, no ground control points are visible due to heavy canopy. While on the other hand, precise georeferencing relies on ground control. As an alternative, we propose to use an available digital elevation model (DEM ) as control. The mathematical framework minimizes the difference between the lidar DEM and the reference DEM. Our solution consists of two steps: initial optimization to find reliable ground points through iterative filtering and georeferencing, and fine optimization to achieve precise georeferencing and lidar system calibration. Through this approach, the wave-form-derived DEM can best fit the reference DEM, with a mean of 0.937 m and standard deviation of 0.792 m, while the time-synchronization offset and boresight angles are simultaneously determined, i.e., self-calibrated. This development provides a novel georeferencing approach with self-calibration for lidar data without using conventional ground control points. Numéro de notice : A2021-056 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.87.1.43 date de publication en ligne : 01/01/2021 En ligne : https://doi.org/10.14358/PERS.87.1.43 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96766 [article]

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Geometric modelling and calibration of a spherical camera imaging system / Derek D. Lichti in Photogrammetric record, vol 35 n° 170 (June 2020)  

Public [article]  inPhotogrammetric record > vol 35 n° 170 (June 2020) . - pp 123 - 142 Titre : Geometric modelling and calibration of a spherical camera imaging system Type de document : Article/Communication Auteurs : Derek D. Lichti, Auteur ; David Jarron, Auteur ; Wynand Tredoux, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 123 - 142 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] acquisition d'images [Termes IGN] autoétalonnage [Termes IGN] chambre 3D [Termes IGN] colinéarité [Termes IGN] distorsion radiale [Termes IGN] instrument de photogrammétrie [Termes IGN] modélisation géométrique de prise de vue [Termes IGN] orientation relative [Termes IGN] reconstruction 3D [Termes IGN] système de numérisation mobile Résumé : (auteur) The Ladybug5 is an integrated, multi‐camera system that features a near‐spherical field of view. It is commonly deployed on mobile mapping systems to collect imagery for 3D reality capture. This paper describes an approach for the geometric modelling and self‐calibration of this system. The collinearity equations of the pinhole camera model are augmented with five radial lens distortion terms to correct the severe barrel distortion. Weighted relative orientation stability constraints are added to the self‐calibrating bundle adjustment solution to enforce the angular and positional stability between the Ladybug5’s six cameras. Centimetre‐level 3D reconstruction accuracy can be achieved, with image‐space precision and object‐space accuracy improved by 92% and 93% , respectively, relative to a two‐term lens distortion model. Sub‐pixel interior orientation stability and millimetre‐level relative orientation stability were also demonstrated over a 10‐month period. Numéro de notice : A2020-401 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/phor.12315 date de publication en ligne : 29/06/2020 En ligne : https://doi.org/10.1111/phor.12315 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95438 [article]

Method for real-time self-calibrating GLONASS code inter-frequency bias and improvements on single point positioning / Liang Chen in GPS solutions, vol 22 n° 4 (October 2018)  

Public [article]  inGPS solutions > vol 22 n° 4 (October 2018) Titre : Method for real-time self-calibrating GLONASS code inter-frequency bias and improvements on single point positioning Type de document : Article/Communication Auteurs : Liang Chen, Auteur ; Min Li, Auteur ; Zhigang Hu, Auteur ; et al., Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] autoétalonnage [Termes IGN] données GLONASS [Termes IGN] données GPS [Termes IGN] erreur systématique [Termes IGN] positionnement ponctuel précis [Termes IGN] temps réel Mots-clés libres : code inter-frequency bias (cIFB) Résumé : (Auteur) Utilization of frequency-division multiple access (FDMA) leads to GLONASS pseudorange and carrier phase observations suffering from variable levels inter-frequency bias (IFB). The bias related with carrier phase can be absorbed by ambiguities. However, the unequal code inter-frequency bias (cIFB) will degrade the accuracy of pseudorange observations, which will affect positioning accuracy and convergence of precise point positioning (PPP) when including GLONASS satellites. Based on observations made on un-differenced (UD) ionospheric-free combinations, GLONASS cIFB parameters are estimated as a constant to achieve GLONASS cIFB real-time self-calibration on a single station. A total of 23 stations, with different manufacturing backgrounds, are used to analyze the characteristics of GLONASS cIFB and its relationship with variable receiver hardware. The results show that there is an obvious common trend in cIFBs estimated using broadcast ephemeris for all of the different manufacturers, and there are unequal GLONASS inter-satellite cIFB that match brand manufacture. In addition, a particularly good consistency is found between self-calibrated receiver-dependent GLONASS cIFB and the IFB products of the German Research Centre for Geosciences (GFZ). Via a comparative experiment, it is also found that the algorithm of cIFB real-time self-calibration not only corrects receiver-dependent cIFB, but can moreover eliminate satellite-dependent cIFB, providing more stable results and further improving global navigation satellite system (GNSS) point positioning accuracy. The root mean square (RMS) improvements of single GLONASS standard point positioning (SPP) reach up to 54.18 and 53.80% in horizontal and vertical direction, respectively. The study’s GLONASS cIFB self-estimation can realize good self-consistency between cIFB and stations, working to further promote convergence efficiency relative to GPS + GLONASS PPP. An average improvement percentage of 19.03% is observed, realizing a near-consistent accuracy with GPS + GLONASS fusion PPP. Numéro de notice : A2018-378 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-018-0774-2 date de publication en ligne : 17/08/2018 En ligne : https://doi.org/10.1007/s10291-018-0774-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90782 [article]

Self-calibration of omnidirectional multi-cameras including synchronization and rolling shutter / Thanh-Tin Nguyen in Computer Vision and image understanding, vol 162 (September 2017)  

Public [article]  inComputer Vision and image understanding > vol 162 (September 2017) . - pp 166 - 184 Titre : Self-calibration of omnidirectional multi-cameras including synchronization and rolling shutter Type de document : Article/Communication Auteurs : Thanh-Tin Nguyen, Auteur ; Maxime Lhuillier, Auteur Année de publication : 2017 Article en page(s) : pp 166 - 184 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] autoétalonnage [Termes IGN] compensation par faisceaux [Termes IGN] image vidéo [Termes IGN] séquence d'images [Termes IGN] structure-from-motion [Termes IGN] synchronisation Résumé : (auteur) 360° and spherical cameras become popular and are convenient for applications like immersive videos. They are often built by fixing together several fisheye cameras pointing in different directions. However their complete self-calibration is not easy since the consumer fisheyes are rolling shutter cameras which can be unsynchronized. Our approach does not require a calibration pattern. First the multi-camera model is initialized thanks to assumptions that are suitable to an omnidirectional camera without a privileged direction: the cameras have the same setting and are roughly equiangular. Second a frame-accurate synchronization is estimated from the instantaneous angular velocities of each camera provided by monocular structure-from-motion. Third both inter-camera poses and intrinsic parameters are refined using multi-camera structure-from-motion and bundle adjustment. Last we introduce a bundle adjustment that estimates not only the usual parameters but also a sub-frame-accurate synchronization and the rolling shutter. We experiment using videos taken by consumer cameras mounted on a helmet and moving along trajectories of several hundreds of meters or kilometers, and compare our results to ground truth. Numéro de notice : A2017-562 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.cviu.2017.08.010 En ligne : https://doi.org/10.1016/j.cviu.2017.08.010 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86643 [article]

Camera self-calibration with lens distortion from a single image / Dan Liu in Photogrammetric Engineering & Remote Sensing, PERS, vol 82 n° 5 (May 2016)  

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Improved area-based deformation analysis of a radio telescope’s main reflector based on terrestrial laser scanning / Christoph Holst in Journal of applied geodesy, vol 9 n° 1 (March 2015)  

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In-flight photogrammetric camera calibration and validation via complementary lidar / A.S. Gneeniss in ISPRS Journal of photogrammetry and remote sensing, vol 100 (February 2015)  

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

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Multi-feature based boresight self-calibration of a terrestrial mobile mapping system / Ting On Chan in ISPRS Journal of photogrammetry and remote sensing, vol 82 (August 2013)

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Geometric analysis and self-calibration of ADS40 imagery / Sara Gonzalez in Photogrammetric record, vol 28 n° 142 (June - August 2013)  

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Automatic camera calibration in close range photogrammetry / Clive Simpson Fraser in Photogrammetric Engineering & Remote Sensing, PERS, vol 79 n° 4 (April 2013)  

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Accuracy assessment of commercial self-calibrating bundle adjustment routines applied to archival aerial photography / Manuel Angel Aguilar in Photogrammetric record, vol 28 n° 141 (March - May 2013)  

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Correlation analysis of camera self-calibration in close range photogrammetry / Rongfu Tang in Photogrammetric record, vol 28 n° 141 (March - May 2013)  

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Inner constraints for planar features / Derek D. Lichti in Photogrammetric record, vol 28 n° 141 (March - May 2013)  

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