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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 Projets : 1-Pas de projet / Article en page(s) : pp 51 - 66 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] capteur aérien [Termes IGN] compensation par faisceaux [Termes IGN] correction [Termes IGN] création de zone intermédiaire [Termes IGN] distorsion d'image [Termes IGN] étalonnage en vol [Termes IGN] image captée par drone [Termes IGN] MicMac [Termes IGN] obturateur [Termes 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 Affiliation des auteurs : LASTIG MATIS+Ext (2012-2019) 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]

Exemplaires(3)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-2020021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
081-2020023	DEP-RECP	Revue	LASTIG	Dépôt en unité	Exclu du prêt
081-2020022	DEP-RECF	Revue	Nancy	Dépôt en unité	Exclu du prêt

Improving representation of land-use maps derived from object-oriented image classification / Wenxiu Gao in Transactions in GIS, vol 17 n° 3 (June 2013)  

Public [article]  inTransactions in GIS > vol 17 n° 3 (June 2013) . - pp 387 - 405 Titre : Improving representation of land-use maps derived from object-oriented image classification Type de document : Article/Communication Auteurs : Wenxiu Gao, Auteur ; Alfred Stein, Auteur ; Li Yang, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 387 - 405 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] carte d'occupation du sol [Termes IGN] classification orientée objet [Termes IGN] création de zone intermédiaire [Termes IGN] généralisation cartographique [Termes IGN] lissage de données [Termes IGN] polygone [Termes IGN] précision sémantique [Termes IGN] représentation cartographique [Termes IGN] similitude [Termes IGN] système d'information géographique Résumé : (Auteur) Object-oriented (OO) image analysis provides an efficient way to generate vector-format land-cover and land-use maps from remotely sensed images. Such image-derived vector maps, however, are generally presented with congested and twisted polygons with step-like boundaries. They include unclassified polygons and polygons with geometric conflicts such as unreadable small areas and narrow corridors. The complex and poorly readable representations usually make such maps not comply well with the Gestalt principle of cartography. This article describes a framework designed to improve the representation by resolving these problematic polygons. It presents a polygon similarity model integrating semantic, geometric and spectral characteristics of the image-derived polygons to eliminate small and unclassified polygons. In addition, an outward-inward-buffering approach is presented to resolve the narrow-corridor conflicts of a polygon and improve its overall appearance. A case study demonstrates that the implementation of the framework reduces the number of the polygons by 32% and the length of the polygon boundaries by 20%. At the same time, it does not cause distinct changes the distribution of land-use types (less than 0.05%) and the overall accuracy (decreased only 0.02%) as compared with the original image-derived land-use maps. We conclude that the presented framework and models effectively improve the overall representation of image-derived maps without distinct changes in their semantic characteristics and accuracy. Numéro de notice : A2013-290 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1467-9671.2012.01368.x Date de publication en ligne : 06/11/2012 En ligne : https://doi.org/10.1111/j.1467-9671.2012.01368.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32428 [article]

A new methodology for measuring coastline recession using buffering and non-linear least squares estimation / J. Heo in International journal of geographical information science IJGIS, vol 23 n°9-10 (september 2009)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 23 n°9-10 (september 2009) . - pp 1165 - 1177 Titre : A new methodology for measuring coastline recession using buffering and non-linear least squares estimation Type de document : Article/Communication Auteurs : J. Heo, Auteur ; J.H. Kim, Auteur ; J.W. Kim, Auteur Année de publication : 2009 Article en page(s) : pp 1165 - 1177 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG [Termes IGN] analyse comparative [Termes IGN] création de zone intermédiaire [Termes IGN] érosion côtière [Termes IGN] ligne de base [Termes IGN] littoral [Termes IGN] méthode des moindres carrés [Termes IGN] segmentation dynamique [Termes IGN] variabilité Résumé : (Auteur) Coastline recession is one of the best indicators of coastal erosion. Three methods for computing coastline recession - the baseline approach, the dynamic segmentation approach and the area-based approach - have been used, each of which has one or more drawbacks. To overcome these problems, a new methodology for measuring coastline recession is proposed, using buffering and non-linear least squares estimation. The proposed method was compared with the three existing methods with respect to two simulated cases and two real coastlines. Test results confirmed that the new method is more reliable than the three other methods, all of which are susceptible to variability of recession, scale, number of line segments, length of coastlines and direction of the baseline. The proposed method, incorporating two physically meaningful values - magnitude and variability of coastline recession according to the mean and standard deviation of coastline offsets, respectively - presents itself as an effective alternative method of assessing coastline recession. Copyright Taylor & Francis Numéro de notice : A2009-384 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810802035642 En ligne : https://doi.org/10.1080/13658810802035642 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30014 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-09061	RAB	Revue	Centre de documentation	En réserve L003	Disponible