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Improving the assessment of ICESat water altimetry accuracy accounting for autocorrelation / Hani Abdallah in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 (November 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 (November 2011) . - pp 833 - 844 Titre : Improving the assessment of ICESat water altimetry accuracy accounting for autocorrelation Type de document : Article/Communication Auteurs : Hani Abdallah, Auteur ; Jean-Stéphane Bailly, Auteur ; Nicolas Baghdadi, Auteur ; Nicolas Lemarquand, Auteur Année de publication : 2011 Article en page(s) : pp 833 - 844 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] altimétrie satellitaire par laser [Termes IGN] autocorrélation spatiale [Termes IGN] données altimétriques [Termes IGN] données ICEsat [Termes IGN] Etats-Unis [Termes IGN] filtrage du rayonnement [Termes IGN] forme d'onde [Termes IGN] géostatistique [Termes IGN] Grands Lacs [Termes IGN] incertitude géométrique [Termes IGN] précision altimétrique [Termes IGN] ressources en eau Résumé : (Auteur) Given that water resources are scarce and are strained by competing demands, it has become crucial to develop and improve techniques to observe the temporal and spatial variations in the inland water volume. Due to the lack of data and the heterogeneity of water level stations, remote sensing, and especially altimetry from space, appear as complementary techniques for water level monitoring. In addition to spatial resolution and sampling rates in space or time, one of the most relevant criteria for satellite altimetry on inland water is the accuracy of the elevation data. Here, the accuracy of ICESat LIDAR altimetry product is assessed over the Great Lakes in North America. The accuracy assessment method used in this paper emphasizes on autocorrelation in high temporal frequency ICESat measurements. It also considers uncertainties resulting from both in situ lake level reference data. A probabilistic upscaling process was developed. This process is based on several successive ICESat shots averaged in a spatial transect accounting for autocorrelation between successive shots. The method also applies pre-processing of the ICESat data with saturation correction of ICESat waveforms, spatial filtering to avoid measurement disturbance from the land–water transition effects on waveform saturation and data selection to avoid trends in water elevations across space. Initially this paper analyzes 237 collected ICESat transects, consistent with the available hydrometric ground stations for four of the Great Lakes. By adapting a geostatistical framework, a high frequency autocorrelation between successive shot elevation values was observed and then modeled for 45% of the 237 transects. The modeled autocorrelation was therefore used to estimate water elevations at the transect scale and the resulting uncertainty for the 117 transects without trend. This uncertainty was 8 times greater than the usual computed uncertainty, when no temporal correlation is taken into account. This temporal correlation, corresponding to approximately 11 consecutive ICESat shots, could be linked to low transmitted ICESat GLAS energy and to poor weather conditions. Assuming Gaussian uncertainties for both reference data and ICESat data upscaled at the transect scale, we derived GLAS deviations statistics by averaging the results at station and lake scales. An overall bias of -4.6 cm (underestimation) and an overall standard deviation of 11.6 cm were computed for all lakes. Results demonstrated the relevance of taking autocorrelation into account in satellite data uncertainty assessment. Numéro de notice : A2011-471 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.09.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.09.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31365 [article]

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Improving the Wishart synthetic aperture radar image classifications through deterministic simulated annealing / F. Sanchez-Llado in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 (November 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 (November 2011) . - pp 845 - 857 Titre : Improving the Wishart synthetic aperture radar image classifications through deterministic simulated annealing Type de document : Article/Communication Auteurs : F. Sanchez-Llado, Auteur ; G. Pajares, Auteur ; C. Lopez-Martinez, Auteur Année de publication : 2011 Article en page(s) : pp 845 - 857 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] algorithme du recuit simulé [Termes IGN] classification dirigée [Termes IGN] données polarimétriques [Termes IGN] image radar moirée [Termes IGN] loi de Wishart Résumé : (Auteur) This paper proposes the use of Deterministic Simulated Annealing (DSA) for Synthetic Aperture Radar (SAR) image classification for cluster refinement. We use the initial classification provided by the maximum-likelihood classifier based on the complex Wishart distribution that is then supplied to the DSA optimization approach. The goal is to improve the classification results obtained by the Wishart approach. The improvement is verified by computing a cluster separability coefficient. During the DSA optimization process, for each iteration and for each pixel, two consistency coefficients are computed taking into account two kinds of relations between the pixel under consideration and its neighbors. Based on these coefficients and on the information coming from the pixel itself, it is re-classified. Several experiments are carried out to verify that the proposed approach outperforms the Wishart strategy. We try to improve the classification results by considering the spatial influences received by a pixel through its neighbors. Finally, a link about the contribution of DSA to thematic mapping is also established. Numéro de notice : A2011-472 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.09.007 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.09.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31366 [article]

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Using snakes for the registration of topographic road database objects to ALS features / J. Göpfert in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 (November 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 (November 2011) . - pp 858 - 871 Titre : Using snakes for the registration of topographic road database objects to ALS features Type de document : Article/Communication Auteurs : J. Göpfert, Auteur ; Franz Rottensteiner, Auteur ; Christian Heipke, Auteur Année de publication : 2011 Article en page(s) : pp 858 - 871 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] algorithme snake [Termes IGN] appariement de données localisées [Termes IGN] base de données routières [Termes IGN] contour [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] données topographiques [Termes IGN] modèle numérique de paysage [Termes IGN] objet géographique [Termes IGN] optimisation (mathématiques) [Termes IGN] réseau routier Résumé : (Auteur) For historical reasons many national mapping agencies store their topographic data in a dual system consisting of a Digital Landscape Model (DLM) and a Digital Terrain Model (DTM). The DLM contains 2D vector data representing objects on the Earth’s surface, such as roads and rivers, whereas the DTM is a 2.5D representation of the related height information, often acquired by Airborne Laser Scanning (ALS). Today, many applications require reliable 3D topographic data. Therefore, it is advantageous to convert the dual system into a 3D DLM. However, as a result of different methods of acquisition, processing, and modelling, the registration of the two data sets often presents difficulties. Thus, a straightforward integration of the DTM and DLM might lead to inaccurate and semantically incorrect 3D objects. $In this paper we propose a new method for the fusion of the two data sets that exploits parametric active contours (also called snakes), focusing on road networks. For that purpose, the roads from a DLM initialise the snakes, defining their topology and their internal energy, whereas ALS features exert external forces to the snake via the image energy. After the optimisation process the shape and position of the snakes should coincide with the ALS features. With respect to the robustness of the method several known modifications of snakes are combined in a consistent framework for DLM road network adaptation. One important modification redefines the standard internal energy and thus the geometrical model of the snake in order to prevent changes in shape or position not caused by significant features in the image energy. For this purpose, the initial shape is utilized creating template-like snakes with the ability of local adaptation. This is one crucial point towards the applicability of the entire method considering the strongly varying significance of the ALS features. Other concepts related to snakes are integrated which enable our method to model network and ribbon-like characteristics simultaneously. Additionally, besides ALS road features information about context objects, such as bridges and buildings, is introduced as part of the image energy to support the optimisation process. Meaningful examples are presented that emphasize and evaluate the applicability of the proposed method. Numéro de notice : A2011-473 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.08.008 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.08.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31367 [article]

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An approach to the radiometric aerotriangulation of photogrammetric images / David Hernandez-Lopez in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 (November 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 (November 2011) . - pp 883 - 893 Titre : An approach to the radiometric aerotriangulation of photogrammetric images Type de document : Article/Communication Auteurs : David Hernandez-Lopez, Auteur ; B. Felipe-Garcia, Auteur ; J. Gonzalez Piqueras, Auteur ; G. Villa Alcazar, Auteur Année de publication : 2011 Article en page(s) : pp 883 - 893 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] correction radiométrique [Termes IGN] distribution du coefficient de réflexion bidirectionnelle BRDF [Termes IGN] image aérienne [Termes IGN] modèle de transfert radiatif [Termes IGN] orientation externe [Termes IGN] orthoimage [Termes IGN] points homologues [Termes IGN] qualité radiométrique (image) [Termes IGN] zone homogène Résumé : (Auteur) Harnessing the radiometric information provided by photogrammetric flights could be useful in increasing the thematic applications of aerial images. The aim of this paper is to improve relative and absolute homogenization in aerial images by applying atmospheric correction and treatment of bidirectional effects. We propose combining remote sensing methodologies based on radiative transfer models and photogrammetry models, taking into account the three-dimensional geometry of the images (external orientation and Digital Elevation Model). The photogrammetric flight was done with a Z/I Digital Mapping Camera (DMC) with a Ground Sample Distance (GSD) of 45 cm. Spectral field data were acquired by defining radiometric control points in order to apply atmospheric correction models, obtaining calibration parameters from the camera and surface reflectance images. Kernel-driven models were applied to correct the anisotropy caused by the bidirectional reflectance distribution function (BRDF) of surfaces viewed under large observation angles with constant illumination, using the overlapping area between images and the establishment of radiometric tie points. Two case studies were used: 8-bit images with applied Lookup Tables (LUTs) resulting from the conventional photogrammetric workflow for BRDF studies and original 12-bit images (Low Resolution Color, LRC) for the correction of atmospheric and bidirectional effects. The proposed methodology shows promising results in the different phases of the process. The geometric kernel that shows the best performance is the Lidense kernel. The homogenization factor in 8-bit images ranged from 6% to 25% relative to the range of digital numbers (0–255), and from 18% to 35% relative to levels of reflectance (0–100) in the 12-bit images, representing a relative improvement of approximately 1–30%, depending on the band analyzed. Numéro de notice : A2011-474 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.09.011 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.09.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31368 [article]

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Multi-view dense matching supported by triangular meshes / D. Butalov in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 (November 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 (November 2011) . - pp 907 - 918 Titre : Multi-view dense matching supported by triangular meshes Type de document : Article/Communication Auteurs : D. Butalov, Auteur ; P. Wernerus, Auteur ; Christian Heipke, Auteur Année de publication : 2011 Article en page(s) : pp 907 - 918 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] appariement d'images [Termes IGN] appariement dense [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] maillage par triangles [Termes IGN] précision infrapixellaire [Termes IGN] reconstruction 3D [Termes IGN] semis de points [Termes IGN] séquence d'images [Termes IGN] tessellation Résumé : (Auteur) We present a new procedure to compute dense 3D point clouds from a sequential set of images. This procedure is considered as a second step of a three-step algorithm for 3D reconstruction from image sequences, whose first step consists of image orientation and the last step is shape reconstruction. We assume that the camera matrices as well as a sparse set of 3D points are available and we strive for obtaining a dense and reliable 3D point cloud. Three novel ideas are presented: (1) for sparse tracking and triangulation, the search space for correspondences is reduced to a line segment by means of known camera matrices and disparity ranges are provided by triangular meshes from the already available points; (2) triangular meshes from extended sets of points are used for dense matching, because these meshes help to reconstruct points in weakly textured areas and present a natural way to obtain subpixel accuracy; (3) two non-local optimization methods, namely, 1D dynamic programming along horizontal lines and semi-global optimization were employed for refinement of local results obtained from an arbitrary number of images. All methods were extensively tested on a benchmark data set and an infrared video sequence. Both visual and quantitative results demonstrate the effectiveness of our algorithm. Numéro de notice : A2011-475 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.06.006 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.06.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31369 [article]

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A bundle adjustment approach with inner constraints for the scaled orthographic projection / F. Keith in ISPRS Journal of photogrammetry and remote sensing, vol 66 n° 6 (November 2011)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 66 n° 6 (November 2011) . - pp 919 - 926 Titre : A bundle adjustment approach with inner constraints for the scaled orthographic projection Type de document : Article/Communication Auteurs : F. Keith, Auteur ; F. Blonquist, Auteur ; R. Pack, Auteur Année de publication : 2011 Article en page(s) : pp 919 - 926 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] compensation par faisceaux [Termes IGN] contrainte d'intégrité [Termes IGN] ligne de visée [Termes IGN] projection orthographique Résumé : (Auteur) Bundle adjustment is a method for simultaneously calculating both the interior and exterior orientation parameters of a set of images, and the object-space coordinates of the observed points. In the case of long focal length lenses and narrow field-of-view (FOV) imaging situations, collinearity based (perspective projection) algorithms may result in linear dependencies between parameters that cause solution instability. The use of a scaled orthographic projection model based on linear algebraic formulations was therefore adopted to reduce this risk. Using quaternions, a new mathematical model is derived that includes the partial derivatives as well as the inner constraint equations for a scaled orthographic bundle adjustment. The model was then tested using two image sets of a single, small vessel (about 6 m length) with a cube target of known dimensions at two distinct ranges; perspective solutions were also calculated for comparison. RMS residual errors of 0.74–0.78 pixels associated with the new method compare favorably to a residual error range of 0.59–0.74 pixels using a perspective bundle adjustment of the same target points. Relative precisions (as a ratio of target size) of between 1:1650 and 1:750 have been achieved at ranges of 375 m and 850 m, respectively, given comparisons with the known cube dimensions. A third image dataset consisting of a network of 16 images was solved with a 1:2200 relative precision showing the new method can successfully handle high redundancy. For the experiments that were conducted, the new method was found to produce less precise results than the perspective bundle solution for a FOV of 0.50–0.65° where the object fills 5–8% of the image. However, it was found to match the precision of the perspective model (with an uncalibrated camera) for a FOV of 0.20–0.30° where the object of interest fills only 1–2% of the full image. Numéro de notice : A2011-476 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.07.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.07.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31370 [article]

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