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Three-Corner Hat for the assessment of the uncertainty of non-linear residuals of space-geodetic time series in the context of terrestrial reference frame analysis / Claudio Abbondanza in Journal of geodesy, vol 89 n° 4 (April 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 4 (April 2015) . - pp 313-329 Titre : Three-Corner Hat for the assessment of the uncertainty of non-linear residuals of space-geodetic time series in the context of terrestrial reference frame analysis Type de document : Article/Communication Auteurs : Claudio Abbondanza, Auteur ; Zuheir Altamimi , Auteur ; T.M. Chin, Auteur ; Richard S. Gross, Auteur ; Michael B. Heflin, Auteur ; J. W. Parker, Auteur ; X. Wu, Auteur Année de publication : 2015 Article en page(s) : pp 313-329 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] co-positionnement [Termes IGN] corrélation temporelle [Termes IGN] estimation de cohérence [Termes IGN] hauteur ellipsoïdale [Termes IGN] incertitude de position [Termes IGN] International Terrestrial Reference Frame [Termes IGN] série temporelle [Termes IGN] signal GPS Résumé : (auteur) We discuss the application of the Three-Corner Hat (TCH) to time series of space-geodetic station position residuals with the purpose of characterizing the uncertainties of GPS, VLBI, SLR, DORIS for the International Terrestrial Reference Frame (ITRF) determination. Adopting simulations, we show that, in the absence of time-correlated errors, TCH is able to fully recover the nominal uncertainties of groups of observations whose intrinsic precisions are remarkably dissimilar to one another, as is the case for the space-geodetic techniques. When time-correlated errors are predominant, as it happens with GPS, TCH is affected by the increased variance of the observations and its estimates are positively biased. TCH applied to 16 ITRF co-located sites confirms that GPS, albeit affected by time-correlated errors, is the most precise of the space-geodetic techniques. GPS median uncertainties are 1.1, 1.2 and 2.8 mm, for the north, east and height component, respectively. VLBI performs particularly well in the horizontal component, the median uncertainties being ≈2 mm. The height component is ∼3 times larger than the GPS one. SLR and DORIS median uncertainties exceed by far the 7 mm level on all of the three components. Comparing TCH results with station position repeatabilities, we find that the two metrics are in striking agreement for VLBI and DORIS, but not for SLR and GPS. The inconsistencies between TCH and station repeatabilities for co-located GPS and SLR point to the presence of either specific station-dependent biases or low-quality co-locations. Scaling factors derived adopting the ratio between TCH and median formal errors on the positions suggest the station position covariances have to be up-scaled for VLBI, SLR, DORIS and down-scaled for GPS. Numéro de notice : A2015-340 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0777-x date de publication en ligne : 18/11/2014 En ligne : https://doi.org/10.1007/s00190-014-0777-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76709 [article]

A multidimensional extension of the concept of coherence in polarimetric SAR interferometry / Jose Luis Alvarez-Perez in IEEE Transactions on geoscience and remote sensing, vol 53 n° 3 (March 2015)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 3 (March 2015) . - pp 1257 - 1270 Titre : A multidimensional extension of the concept of coherence in polarimetric SAR interferometry Type de document : Article/Communication Auteurs : Jose Luis Alvarez-Perez, Auteur Année de publication : 2015 Article en page(s) : pp 1257 - 1270 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] données polarimétriques [Termes IGN] estimation de cohérence [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] Pol-INSAR [Termes IGN] polarimétrie radar [Termes IGN] rayonnement électromagnétique [Termes IGN] tenseur Résumé : (Auteur) Interferometric synthetic aperture radar (InSAR) is a phase-based radar signal processing technique that has been addressed from a polarimetric point of view since the late 1990s, starting with Cloude and Papathanassiou's foundational work. Polarimeric InSAR (PolInSAR) has consolidated as an active field of research in parallel to non-PolInSAR. Regarding the latter, there have been a number of issues that were discussed in an earlier paper from which some other questions related to Cloude's PolInSAR come out naturally. In particular, they affect the usual understanding of coherence and statistical independence. Coherence involves the behavior of electromagnetic waves in at least a pair of points, and it is crucially related to the statistical independence of scatterers in a complex scene. Although this would seem to allow PolInSAR to overcome the difficulties involving the controversial confusion between statistical independence and polarization as present in PolSAR, Cloude's PolInSAR originally inherited the idea of separating physical contributors to the scattering phenomenon through the use of singular values and vectors. This was an assumption consistent with Cloude's PolSAR postulates that was later set aside. We propose the introduction of a multidimensional coherence tensor that includes PolInSAR's polarimetric interferometry matrix Ω12 as its 2-D case. We show that some important properties of the polarimetric interferometry matrix are incidental to its bidimensionality. Notably, this exceptional behavior in 2-D seems to suggest that the singular value decomposition (SVD) of Ω12 does not provide a physical insight into the scattering problem in the sense of splitting different scattering contributors. It might be argued that Cloude's PolInSAR in its current form does not rely on the SVD of Ω12 but on other underlying optimization schemes. The drawbacks of such ulterior developments and the failu- e of the maximum coherence separation procedure to be a consistent scheme for surface topography estimation in a two-layer model are discussed in depth in this paper. Nevertheless, turning back to the SVD of Ω12, the use of the singular values of a prewhitened version of Ω12 is consistent with a leading method of characterizing coherence in modern Optics. For this reason, the utility of the SVD of Ω12 as a means of characterizing coherence is analyzed here and extended to higher dimensionalities. Finally, these extensions of the concept of coherence to the multidimensional case are tested and compared with the 2-D case by numerically simulating the scattered electromagnetic field from a rough surface. Numéro de notice : A2015-138 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2336805 date de publication en ligne : 31/07/2014 En ligne : https://doi.org/10.1109/TGRS.2014.2336805 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75805 [article]

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Automatic pyramidal intensity-based laser scan matcher for 3D modeling of large scale unstructured environments / Daniela Craciun (2008)  

Public Titre : Automatic pyramidal intensity-based laser scan matcher for 3D modeling of large scale unstructured environments Type de document : Article/Communication Auteurs : Daniela Craciun , Auteur ; Nicolas Paparoditis , Auteur ; Francis Schmitt, Auteur Editeur : New-York : IEEE Computer society Année de publication : 2008 Projets : 2-Pas d'info accessible - article non ouvert / Conférence : CRV 2008, 5th Canadian Conference on Computer and Robot Vision 28/05/2008 30/05/2008 Windsor Ontario - Canada Proceedings IEEE Importance : pp 18 - 25 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] algorithme ICP [Termes IGN] alignement des données [Termes IGN] appariement de données localisées [Termes IGN] chaîne de traitement [Termes IGN] corrélation automatique de points homologues [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] estimation de cohérence [Termes IGN] grotte [Termes IGN] image panoramique [Termes IGN] image terrestre [Termes IGN] lever souterrain [Termes IGN] modèle 3D du site [Termes IGN] site archéologique Résumé : (auteur) We are developing a vision-based system for photorealistic 3D modeling of previously unknown, complex and unstructured underground environments. Nowadays, laser range finders allow us to build 3D maps of the environment by taking multiple scans from different viewpoints. The scans are usually aligned via two post-processing steps: first, a coarse alignment is provided by an operator and second, a fine solution is computed via Iterative ClosestPoint algorithm. In this paper we describe an automatic on line scan matcher system which replaces the two post-processing steps of the existing methods. The scan matcher is powered by a pyramidal pairwise matching of 2D intensity panoramic views using a dense correlation procedure via quaternions. The proposed method does not rely on feature extraction providing thus an environment-independent solution for the scan matching task. The pyramidal structure provides a fast and accurate scan alignment in a coarse to fine approach. The scan matcher allows us to automatically build in situ 3D mosaics by integrating multiple partially overlapping scans based on a topological inference criterion which improves the global matching consistency. Tests on real data from two prehistoric caves are presented and a performance evaluation is given. Numéro de notice : C2008-026 Affiliation des auteurs : MATIS+Ext (1993-2011) Thématique : IMAGERIE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1109/CRV.2008.35 En ligne : https://doi.org/10.1109/CRV.2008.35 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97388

Precision of points computed from intersections of lines or planes / P. Cederholm in Surveying and land information science, vol 64 n° 3 (01/09/2004)

Public [article]  inSurveying and land information science > vol 64 n° 3 (01/09/2004) . - pp 163 - 170 Titre : Precision of points computed from intersections of lines or planes Type de document : Article/Communication Auteurs : P. Cederholm, Auteur Année de publication : 2004 Article en page(s) : pp 163 - 170 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] estimation de cohérence [Termes IGN] intersection de ligne [Termes IGN] lasergrammétrie [Termes IGN] méthode des moindres carrés [Termes IGN] positionnement par GPS [Termes IGN] précision géométrique (imagerie) [Termes IGN] semis de points Résumé : (Auteur) Not all points are directly accessible when doing detail surveys with GPS. This paper suggests a method for estimating these points. The points are computed from intersections of lines that are surveyed with GPS. The lines are computed by least squares estimation. Further, the suggested method estimates the precision of the points. When using laser scanning a similar problem appears. A laser scanner captures a 3D point cloud, not the points of real interest. The suggested method can be used to compute three-dimensional coordinates of the intersection of three planes estimated from the point cloud. The method can also be used to predict the precision of the points prior to a survey. An example is given. Numéro de notice : A2004-602 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27118 [article]

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Speckle filtering and coherence estimation of polarimetric SAR interferometry data for forest applications / Jong-Sen Lee in IEEE Transactions on geoscience and remote sensing, vol 41 n° 10 (October 2003)

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 41 n° 10 (October 2003) . - pp 2254 - 2263 Titre : Speckle filtering and coherence estimation of polarimetric SAR interferometry data for forest applications Type de document : Article/Communication Auteurs : Jong-Sen Lee, Auteur ; S.R. Cloude, Auteur ; K.P. Papathanassiou, Auteur ; M.R. Grunes, Auteur ; I.H. Woodhouse, Auteur Année de publication : 2003 Article en page(s) : pp 2254 - 2263 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] bande L [Termes IGN] estimation de cohérence [Termes IGN] filtre de déchatoiement [Termes IGN] image radar moirée [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] matrice [Termes IGN] Pol-INSAR Numéro de notice : A2003-353 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26433 [article]

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Coherent radar performance estimation / J.L. Kurtz (1993)

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