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An automatic workflow for orientation of historical images with large radiometric and geometric differences / Ferdinand Maiwald in Photogrammetric record, vol 36 n° 174 (June 2021)  

Public [article]  inPhotogrammetric record > vol 36 n° 174 (June 2021) . - pp 77 - 103 Titre : An automatic workflow for orientation of historical images with large radiometric and geometric differences Type de document : Article/Communication Auteurs : Ferdinand Maiwald, Auteur ; Hans-Gerd Maas, Auteur Année de publication : 2021 Article en page(s) : pp 77 - 103 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] appariement de formes [Termes IGN] artefact [Termes IGN] classification par réseau neuronal convolutif [Termes IGN] extraction de traits caractéristiques [Termes IGN] image ancienne [Termes IGN] plus proche voisin, algorithme du [Termes IGN] réalité augmentée [Termes IGN] réalité virtuelle [Termes IGN] reconstruction 3D [Termes IGN] scène urbaine [Termes IGN] SIFT (algorithme) [Termes IGN] structure-from-motion Résumé : (auteur) This contribution proposes a workflow for a completely automatic orientation of historical terrestrial urban images. Automatic structure from motion (SfM) software packages often fail when applied to historical image pairs due to large radiometric and geometric differences causing challenges with feature extraction and reliable matching. As an innovative initialising step, the proposed method uses the neural network D2-Net for feature extraction and Lowe’s mutual nearest neighbour matcher. The principal distance for every camera is estimated using vanishing point detection. The results were compared to three state-of-the-art SfM workflows (Agisoft Metashape, Meshroom and COLMAP) with the proposed workflow outperforming the other SfM tools. The resulting camera orientation data are planned to be imported into a web and virtual/augmented reality (VR/AR) application for the purpose of knowledge transfer in cultural heritage. Numéro de notice : A2021-471 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12363 Date de publication en ligne : 06/06/2021 En ligne : https://doi.org/10.1111/phor.12363 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97925 [article]

Geometric calibration of satellite laser altimeters based on waveform matching / Shaoning Li in Photogrammetric record, vol 36 n° 174 (June 2021)  

Public [article]  inPhotogrammetric record > vol 36 n° 174 (June 2021) . - pp 104 - 123 Titre : Geometric calibration of satellite laser altimeters based on waveform matching Type de document : Article/Communication Auteurs : Shaoning Li, Auteur ; Chaokui Li, Auteur ; Guo Zhang, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 104 - 123 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] données ICEsat [Termes IGN] étalonnage géométrique [Termes IGN] forme d'onde pleine [Termes IGN] Geoscience Laser Altimeter System [Termes IGN] lidar à retour d'onde complète [Termes IGN] modèle numérique de surface [Termes IGN] point d'appui [Termes IGN] précision altimétrique [Termes IGN] signal laser [Termes IGN] télémétrie laser Résumé : (auteur) This study proposes a new geometric calibration method for satellite laser altimeters based on waveform matching to solve the problems of poor initial pointing accuracy and a lack of control data. This non-real-time method obtains ground control points without a fixed calibration field. First, a large area with stepped surfaces is chosen from the laser altimetry coverage. Then, the laser echo waveforms are simulated using digital surface model (DSM) data of the stepped features. The real echo waveform attempts to match the simulated echo waveforms through a waveform matching model using a global constraint. Next, the control points of the laser altimeter are obtained through waveform matching. Finally, a geometric calibration model for laser altimeters is proposed to compensate for laser pointing and ranging errors. Two experiments were conducted to verify the calibration method using ICESat/GLAS data and airborne large-footprint laser data. Experimental results confirm that the method is feasible and results in an improvement in the elevation accuracy for the airborne altimeter from 2 to 0.5 m. Numéro de notice : A2021-473 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12362 Date de publication en ligne : 07/05/2021 En ligne : https://doi.org/10.1111/phor.12362 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97926 [article]

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] Acquisition d'image(s) et de donnée(s) [Termes IGN] appariement de formes [Termes IGN] auto-étalonnage [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 Thématique : IMAGERIE 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]