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Real-time object detection with sub-pixel accuracy using the level set method / F. Burkert in Photogrammetric record, vol 26 n° 134 (June - August 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 134 (June - August 2011) . - pp 154 - 170 Titre : Real-time object detection with sub-pixel accuracy using the level set method Type de document : Article/Communication Auteurs : F. Burkert, Auteur ; Matthias Butenuth, Auteur ; M. Ulrich, Auteur Année de publication : 2011 Article en page(s) : pp 154 - 170 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] classification à base de connaissances [Termes IGN] détection d'objet [Termes IGN] détection de contours [Termes IGN] niveau de gris (image) [Termes IGN] précision infrapixellaire [Termes IGN] reconnaissance d'objets [Termes IGN] temps réel Résumé : (Auteur) This paper presents a method for object detection with sub-pixel accuracy in digital images satisfying real-time applications. The method uses an approximation of the level-set-based contour evolution, which applies only integer operations in a fast two-cycle algorithm to achieve real-time performance. Level-set-based contour evolution forms a part of the geometric active contour process, which combines image data and a priori geometric knowledge of an object to be evolved over an image towards the object border. The algorithm avoids the solution of partial differential equations. Instead only integer operations are applied and the contour evolution is performed by using a two-cycle algorithm. The proposed method for object detection with sub-pixel accuracy refines the pixel-accurate result of the level-set-based contour evolution algorithm by using a fast parabolic fitting mechanism. Sub-pixel accuracy of the resulting object contours is achieved by adjusting every contour point towards the nearby maximum of the image gradient. Real-time performance can be provided because the adjustment is performed only once after the contour evolution. Experimental results with images from industry, photogrammetry, remote sensing and medicine show the functionality and applicability of this method to several fields of work. In addition, the experiments are evaluated by applying quality measures for the geometric accuracy and the run time. Numéro de notice : A2011-238 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00633.x Date de publication en ligne : 06/06/2011 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00633.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31016 [article]

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TLS data denoising by range image processing / Eddy Smigiel in Photogrammetric record, vol 26 n° 134 (June - August 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 134 (June - August 2011) . - pp 171 - 189 Titre : TLS data denoising by range image processing Type de document : Article/Communication Auteurs : Eddy Smigiel, Auteur ; Emmanuel Alby, Auteur ; Pierre Grussenmeyer, Auteur Année de publication : 2011 Article en page(s) : pp 171 - 189 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] archéologie [Termes IGN] archéométrie [Termes IGN] données laser [Termes IGN] données localisées 2D [Termes IGN] données localisées 3D [Termes IGN] filtrage du bruit [Termes IGN] ondelette [Termes IGN] semis de points [Termes IGN] traitement d'image [Termes IGN] transformation en ondelettes Résumé : (Auteur) The work described in this paper deals with denoising of fine detail in terrestrial laser scanner (TLS) data for close-range applications. In contrast to other denoising methods described in the literature, the method described here puts the problem back into two dimensions. In the proposed method, data from each instrument station is processed by denoising the range image as a 2D function. Then, after denoising, the registration process is applied to obtain the final 3D point cloud. Two image denoising methods are tested. Wavelet analysis and a “non-local means” (NL-means) algorithm are applied to archaeological objects of sizes described as medium (around one cubic metre) and small (around one cubic decimetre). The rich relief of these objects proves the efficiency of the method on all kinds of surface shape. The experience shows that the NL-means method achieves good results: the standard deviation of 2 mm in the raw data is decreased to 1 mm. Besides, NL-means denoising requires very few parameters to be set (generally two) whilst wavelet denoising requires many. Hence, the extreme simplicity of the NL-means method makes it much more efficient and suitable for use by non-specialists. The method, which slightly modifies the standard production process and inherits the algorithmic complexity of the classical 2D image processing schemes, allows the range of applications of TLS to be extended to small and finely detailed objects. Numéro de notice : A2011-239 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00631.x Date de publication en ligne : 06/06/2011 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00631.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31017 [article]

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Photogrammetric processing of low-altitude images acquired by unpiloted aerial vehicles / Y. Zhang in Photogrammetric record, vol 26 n° 134 (June - August 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 134 (June - August 2011) . - pp 190 - 211 Titre : Photogrammetric processing of low-altitude images acquired by unpiloted aerial vehicles Type de document : Article/Communication Auteurs : Y. Zhang, Auteur ; J. Xiong, Auteur ; L. Hao, Auteur Année de publication : 2011 Article en page(s) : pp 190 - 211 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] aérotriangulation numérique [Termes IGN] altitude du capteur [Termes IGN] compensation par faisceaux [Termes IGN] drone [Termes IGN] modélisation 3D [Termes IGN] orientation du capteur [Termes IGN] point d'appui [Termes IGN] SIFT (algorithme) [Termes IGN] traitement parallèle [Termes IGN] trajectoire (véhicule non spatial) Résumé : (Auteur) Low-altitude images acquired by unpiloted aerial vehicles have the advantages of high overlap, multiple viewing angles and very high ground resolution. These kinds of images can be used in various applications that need high accuracy or fine texture. A novel approach is proposed for parallel processing of low-altitude images acquired by unpiloted aerial vehicles, which can automatically fly according to predefined flight routes under the control of an autopilot system. The general overlap and relative rotation angles between two adjacent images are estimated by overall matching with an improved scale-invariant feature transform (SIFT) operator. Precise conjugate points and relative orientation parameters are determined by a pyramid-based least squares image matching strategy and the relative orientation process. Bundle adjustment is performed with automatically matched conjugate points and interactively measured ground control points. After this aerial triangulation process the high-resolution images can be used to advantage in obtaining precise spatial information products such as digital surface models, digital orthophotomaps and 3D city models. A parallel processing strategy is introduced in this paper to improve the computational time of the photogrammetric process. Experimental results show that the proposed approaches are effective for processing low-altitude images, and have high potential for the acquisition of spatial information at large mapping scales, with rapid response and precise modelling in three dimensions. Numéro de notice : A2011-240 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00641.x Date de publication en ligne : 06/06/2016 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00641.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31018 [article]

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Integration of panoramic hyperspectral imaging with terrestrial lidar data / T. Kurz in Photogrammetric record, vol 26 n° 134 (June - August 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 134 (June - August 2011) . - pp 212 - 228 Titre : Integration of panoramic hyperspectral imaging with terrestrial lidar data Type de document : Article/Communication Auteurs : T. Kurz, Auteur ; S. Buckley, Auteur ; John Howell, Auteur Année de publication : 2011 Article en page(s) : pp 212 - 228 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] compensation par faisceaux [Termes IGN] conflation [Termes IGN] données lidar [Termes IGN] géologie locale [Termes IGN] image hyperspectrale [Termes IGN] image panoramique [Termes IGN] image terrestre [Termes IGN] orientation externe [Termes IGN] rayonnement infrarouge Résumé : (Auteur) In many close-range applications it is essential to obtain information about the geometry of the target surface as well as its chemical composition. In this study, close-range hyperspectral imaging was integrated with terrestrial laser scanning to provide mineral and chemical information for geological field studies. The spectral data was collected with the HySpex SWIR-320m sensor, which operates in the infrared spectrum between the wavelengths of 1·3 and 2·5 um. This sensor permits surfaces to be imaged with high spectral resolution, allowing detailed classification and analysis to be carried out. Photogrammetric processing of the hyperspectral imagery was achieved using an existing geometric model for rotating linear-array-based panoramic cameras. Bundle block adjustment of multiple images resulted in the registration of the spectral images in the lidar coordinate system, with a precision of around one image pixel. Although the image and control point network was not optimised for photogrammetric processing, it was possible to recover the exterior camera orientations, as well as additional camera calibration parameters. With the known image orientations, 3D lidar models could be textured with hyperspectral classifications, and the quality of the registration determined. The integration of the hyperspectral image products with the terrestrial lidar data enabled data interpretation and evaluation in a real-world coordinate system, and provided a reliable means of linking material and geometric information. Numéro de notice : A2011-241 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00632.x Date de publication en ligne : 06/06/2011 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00632.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31019 [article]

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Calibrating and validating multispectral 3D imaging systems at a permanent test site: case study with an Intergraph DMC / Eija Honkavaara in Photogrammetric record, vol 26 n° 134 (June - August 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 134 (June - August 2011) . - pp 229 - 249 Titre : Calibrating and validating multispectral 3D imaging systems at a permanent test site: case study with an Intergraph DMC Type de document : Article/Communication Auteurs : Eija Honkavaara, Auteur ; K. Nurminen, Auteur ; Lauri Markelin, Auteur ; J. Suomalainen, Auteur ; Risto Ilves, Auteur Année de publication : 2011 Article en page(s) : pp 229 - 249 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] capteur multibande [Termes IGN] chambre DTC [Termes IGN] DMC [Termes IGN] étalonnage de chambre métrique [Termes IGN] Finlande [Termes IGN] modèle numérique de surface [Termes IGN] qualité géométrique (image) [Termes IGN] qualité radiométrique (image) [Termes IGN] test de performance Résumé : (Auteur) Novel photogrammetric sensors open up new possibilities for measuring the radiometric and geometric properties of the Earth’s surface. To ensure optimal use of these complex, rapidly developing, diverse systems, it is becoming crucial to have a means of calibrating and validating complete imaging systems, and even production lines, in operational conditions. This paper presents a calibration and validation methodology based on a permanent test site (Sjökulla) and demonstrates its use in a calibration and validation campaign for a large-format photogrammetric imaging system, the Intergraph DMC. The major objective of the campaign was to perform acceptance testing of the new camera system procured by the National Land Survey of Finland. The evaluation proved the high geometric and radiometric performance of the imaging system and demonstrated the potential of spectrodirectional photogrammetric 3D imaging. The usability aspects of test site calibration and validation from the point of view of a mapping organisation were also considered. Numéro de notice : A2011-242 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00634.x Date de publication en ligne : 06/06/2019 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00634.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31020 [article]

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Georeferencing performance of THEOS satellite imagery / S. Liu in Photogrammetric record, vol 26 n° 134 (June - August 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 134 (June - August 2011) . - pp 250 - 262 Titre : Georeferencing performance of THEOS satellite imagery Type de document : Article/Communication Auteurs : S. Liu, Auteur ; Clive Simpson Fraser, Auteur ; C. Zhang, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 250 - 262 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] géoréférencement direct [Termes IGN] image à très haute résolution [Termes IGN] image Theos [Termes IGN] ligne de visée [Termes IGN] Melbourne [Termes IGN] modèle géométrique de prise de vue [Termes IGN] orientation du capteur [Termes IGN] point d'appui [Termes IGN] THEOS Résumé : (Auteur) This paper reports on the application of a generic physical sensor orientation model for evaluation of the georeferencing performance of 2 m resolution imagery from the Thailand Earth Observation System (THEOS) satellite. Within the generic sensor orientation model, orbit and attitude data are employed to describe the satellite trajectory, which is further modelled by splines. The satellite orbit and sensor attitude errors are then compensated via sensor orientation adjustment using a modest number of ground control points (GCPs), resulting in improved georeferencing. The generic sensor model and the integration of the THEOS orientation parameters into the model are first described. The presence of errors in the satellite line-of-sight data, which result in imprecise sensor interior orientation are then discussed. Such errors can be effectively accounted for through modelling via a cubic polynomial, leading to sub-pixel georeferencing accuracy. An account is then given of an experimental evaluation of THEOS georeferencing conducted in a well-established testfield near Melbourne, Australia. The results demonstrate that sub-pixel 2D geopositioning accuracy is readily achievable with single THEOS images and within strips of up to three images, with as few as six GCPs to effect an orbit adjustment. However, accuracy decreases to near the 2-pixel level over a strip length of five images. Numéro de notice : A2011-243 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00634.x Date de publication en ligne : 06/06/2011 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00634.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31021 [article]

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