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Error analysis of weekly station coordinates in the DORIS network / Simon D.P. Williams in Journal of geodesy, vol 80 n° 8-11 (November 2006)
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[article]
Titre : Error analysis of weekly station coordinates in the DORIS network Type de document : Article/Communication Auteurs : Simon D.P. Williams, Auteur ; Pascal Willis , Auteur
Année de publication : 2006 Article en page(s) : pp 525 - 539 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] bruit blanc
[Termes IGN] bruit rose
[Termes IGN] calcul d'erreur
[Termes IGN] données DORIS
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] série temporelle
[Termes IGN] station DORIS
[Termes IGN] traitement du signalRésumé : (Auteur) Twelve years of DORIS data from 31 selected sites of the IGN/JPL (Institut Géographique National/Jet Propulsion Laboratory) solution IGNWD05 have been analysed using maximum likelihood estimation (MLE) in an attempt to understand the nature of the noise in the weekly station coordinate time-series. Six alternative noise models in a total of 12 different combinations were used as possible descriptions of the noise. The six noise models can be divided into two natural groups, temporally uncorrelated (white) noise and temporally correlated (coloured) noise. The noise can be described as a combination of variable white noise and one of flicker, first-order Gauss–Markov or power-law noise. The data set as a whole is best described as a combination of variable white noise plus flicker noise. The variable white noise, which is white noise with variable amplitude that is a function of the weekly formal errors multiplied by an estimated scale factor, shows a dependence on site latitude and the number of DORIS-equipped satellites used in the solution. The latitude dependence is largest in the east component due to the near polar orbit of the SPOT satellites. The amplitude of the flicker noise is similar in all three components and equal to about 20 mm/year1/4. There appears to be no latitude dependence of the flicker noise amplitude. The uncertainty in rates (site velocities) after 12 years is just under 1 mm/year. These uncertainties are around 3–4 times larger than if only variable white noise had been assumed, i.e., no temporally correlated noise. A rate uncertainty of 1 mm/year after 12 years in the vertical is similar to that achieved using Global Positioning System (GPS) data but it takes DORIS twice as long to reach 1 mm/year than GPS in the horizontal. The analysis has also helped to identify sites with either anomalous noise characteristics or large noise amplitudes, and tested the validity of previously proposed discontinuities. In addition, several new offsets were found in the time-series that should be used or at least flagged in future work. Copyright Springer Numéro de notice : A2006-534 Affiliation des auteurs : IGN (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0056-6 En ligne : http://doi.org/10.1007/s00190-006-0056-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28257
in Journal of geodesy > vol 80 n° 8-11 (November 2006) . - pp 525 - 539[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-06102 RAB Revue Centre de documentation En réserve L003 Disponible 266-06101 RAB Revue Centre de documentation En réserve L003 Disponible Estimating the noise in space-geodetic positioning: the case of DORIS / Karine Le Bail in Journal of geodesy, vol 80 n° 8-11 (November 2006)
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Titre : Estimating the noise in space-geodetic positioning: the case of DORIS Type de document : Article/Communication Auteurs : Karine Le Bail , Auteur
Année de publication : 2006 Article en page(s) : pp 541 - 565 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] bruit blanc
[Termes IGN] bruit rose
[Termes IGN] données DORIS
[Termes IGN] ENVISAT
[Termes IGN] filtrage du bruit
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] positionnement par DORIS
[Termes IGN] série temporelle
[Termes IGN] SPOT
[Termes IGN] station DORIS
[Termes IGN] TOPEX-Poseidon
[Termes IGN] traitement du signalRésumé : (Auteur) The noise spectrum in DORIS ground-station motion is investigated by means of the Allan variance method applied to the decomposition of the 3D signal into its principal components in the time domain. Sets of weekly position time-series from 1994 to 2005 derived by three IDS Analysis Centres (IGN-JPL, INASAN, and LEGOS-CLS) for 119 stations at 69 sites are considered. The observing satellites are SPOT-2, SPOT-3, SPOT-4, and SPOT-5, TOPEX/Poseidon, and ENVISAT. Annual and semi-annual perturbations, as well as the 117.3-day term associated with the TOPEX/Poseidon orbit, are found at most stations. Their amplitudes reach up to 19.3, 23.7, and 13.3 mm, respectively, for the three analysis centres (ACs). When corrected for these components and a linear drift, the time-series dominantly show white noise (WN) at the 10-45mm level the noise level is the highest in the East direction, probably in connection with the high orbit inclinations. The noise level is minimum for the high latitude stations, mostly and intensively observed by the SPOT satellites, and the determination of the noise type is unclear; longer observation spans would be needed to decide between interannual variations and flicker noise. The improvement in positioning due to the DORIS constellation extension from three to five satellites in 2002, and the network rejuvenation program initiated in 2000, results in a decrease of the noise level by a factor of 1.7 in a WN context, both before and after the changes. One example of the benefit of studying the signal in the time eigenspace domain is the detection of anomalously large WN in the East direction for station HBKB (Hartebeesthoek, Africa) that masks the above-mentioned improvement. Studying the projection on the local frame of the second and third time-eigenspace components, a noise excess is detected in the North direction for some of the ACs. Station stability derived from our time-series analysis confirms, in general, the expected performance based on the careful technical review of the station components (antenna, pillar, etc.). The respective merits of our noise qualification method, based on direct time-series analysis in the time-eigenspace domain without any a priori statistical model, in comparison with other methods, such as the selection of a mixed-noise model by maximum likelihood estimation, are discussed. Copyright Springer Numéro de notice : A2006-535 Affiliation des auteurs : IGN (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0088-y En ligne : https://doi.org/10.1007/s00190-006-0088-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28258
in Journal of geodesy > vol 80 n° 8-11 (November 2006) . - pp 541 - 565[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-06102 RAB Revue Centre de documentation En réserve L003 Disponible 266-06101 RAB Revue Centre de documentation En réserve L003 Disponible A novel method for mapping land cover changes: Incorporating time and space with geostatistics / A. Boucher in IEEE Transactions on geoscience and remote sensing, vol 44 n° 11 Tome 2 (November 2006)
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Titre : A novel method for mapping land cover changes: Incorporating time and space with geostatistics Type de document : Article/Communication Auteurs : A. Boucher, Auteur ; K.C. Seto, Auteur ; A.G. Journel, Auteur Année de publication : 2006 Article en page(s) : pp 3427 - 3435 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] carte d'occupation du sol
[Termes IGN] classification par maximum de vraisemblance
[Termes IGN] classification pixellaire
[Termes IGN] détection de changement
[Termes IGN] données de terrain
[Termes IGN] filtre de déchatoiement
[Termes IGN] géostatistique
[Termes IGN] krigeage
[Termes IGN] série temporelle
[Termes IGN] utilisation du sol
[Termes IGN] variogrammeRésumé : (Auteur) Landsat data are now available for more than 30 years, providing the longest high-resolution record of Earth monitoring. This unprecedented time series of satellite imagery allows for extensive temporal observation of terrestrial processes such as land cover and land use change. However, despite this unique opportunity, most existing change detection techniques do not fully capitalize on this long time series. In this paper, a method that exploits both the temporal and spatial domains of time series satellite data to map land cover changes is presented. The time series of each pixel in the image is modeled with a combination of: 1) pixel-specific remotely sensed data; 2) neighboring pixels derived from ground observation data; and 3) time series transition probabilities. The spatial information is modeled with variograms and integrated using indicator kriging; time series transition probabilities are combined using an information-based cascade approach. This results in a map that is significantly more accurate in identifying when, where, and what land cover changes occurred. For the six images used in this paper, the prediction accuracy of the time series improves significantly, increasing from 31% to 61%, when both space and time are considered with the maximum likelihood. The consideration of spatial continuity also reduced unwanted speckles in the classified images, removing the need for any postprocessing. These results indicate that combining space and time domains significantly improves the accuracy of temporal change detection analyses and can produce high-quality time series land cover maps. Copyright IEEE Numéro de notice : A2006-529 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2006.879113 En ligne : https://doi.org/10.1109/TGRS.2006.879113 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28252
in IEEE Transactions on geoscience and remote sensing > vol 44 n° 11 Tome 2 (November 2006) . - pp 3427 - 3435[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 065-06111B RAB Revue Centre de documentation En réserve L003 Disponible Plate kinematic of Nubia-Somalia using combined DORIS and GPS solution / Jean-Mathieu Nocquet in Journal of geodesy, vol 80 n° 8-11 (November 2006)
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Titre : Plate kinematic of Nubia-Somalia using combined DORIS and GPS solution Type de document : Article/Communication Auteurs : Jean-Mathieu Nocquet , Auteur ; Pascal Willis
, Auteur ; S. Garcia, Auteur
Année de publication : 2006 Article en page(s) : pp 591 - 607 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique (géographie physique)
[Termes IGN] bruit blanc
[Termes IGN] bruit rose
[Termes IGN] champ de vitesse
[Termes IGN] géodynamique
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] Nubie
[Termes IGN] positionnement cinématique
[Termes IGN] positionnement par DORIS
[Termes IGN] positionnement par GPS
[Termes IGN] rift
[Termes IGN] série temporelle
[Termes IGN] Somalie
[Termes IGN] tectonique des plaquesRésumé : (Auteur) We have used up to 12 years of data to assess DORIS performance for geodynamics applications. We first examine the noise characteristics of the DORIS time-series of weekly station coordinates to derive realistic estimates of velocity uncertainties. We find that a combination of white and flicker noise best explains the DORIS time-series noise characteristics. Second, weekly solutions produced by the Institut Géographique National/Jet Propulsion Laboratory (IGN/JPL) DORIS Analysis Centre are combined to derive a global velocity field. This solution is combined with two independent GPS solutions, including 11 sites on Nubia and 5 on the Somalia plate. The combination indicates that DORIS horizontal velocities have an average accuracy of 3 mm/year, with best-determined sites having velocity accuracy better than 1 mm/year (one-sigma levels). Using our combined velocity field, we derive an updated plate kinematics model with a focus on the Nubia–Somalia area. Including DORIS data improves the precision of the angular velocity vector for Nubia by 15%. Our proposed model provides robust bounds on the maximum opening rates along the East African Rift (4.7–6.7 mm/year). It indicates opening rates 15 and 7% slower than values predicted by NUVEL-1A for the southern Atlantic Ocean and Indian Ocean, respectively. These differences are likely to arise from the fact that NUVEL-1A considered Africa as a single non-deforming plate, while here we use a more refined approach. Copyright Springer Numéro de notice : A2006-536 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0078-0 En ligne : https://doi.org/10.1007/s00190-006-0078-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28259
in Journal of geodesy > vol 80 n° 8-11 (November 2006) . - pp 591 - 607[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-06102 RAB Revue Centre de documentation En réserve L003 Disponible 266-06101 RAB Revue Centre de documentation En réserve L003 Disponible A multi-resolution approach for filtering LiDAR altimetry data / José L. Silvan-Cardenas in ISPRS Journal of photogrammetry and remote sensing, vol 61 n° 1 (October 2006)
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Titre : A multi-resolution approach for filtering LiDAR altimetry data Type de document : Article/Communication Auteurs : José L. Silvan-Cardenas, Auteur ; L. Wang, Auteur Année de publication : 2006 Article en page(s) : pp 11 - 22 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] convolution (signal)
[Termes IGN] données altimétriques
[Termes IGN] données lidar
[Termes IGN] filtrage du signal
[Termes IGN] gradient de pente
[Termes IGN] lissage de données
[Termes IGN] modèle numérique de surface
[Termes IGN] modèle numérique de terrainRésumé : (Auteur) Discrimination of above-ground objects from terrain has proven to be surprisingly difficult to automate in computers, especially for large areas of varied terrain characteristics. Several methods have been developed for filtering the LiDAR data, of which three approaches are more prevalent: linear prediction, slope based and morphological filtering. A common ground to all these approaches is that the range of scales at which feature variations exist tends to be smaller than the range of scales at which terrain variations exist. In this paper, a model-based approach is described in which multiscale gradient of the surface variation is computed and used to adaptively erode the gridded LiDAR data within a multi-resolution, analysis–synthesis framework, namely the multiscale Hermite transform (MHT). The method was tested over nineteen datasets, including urban and forest areas. An average coefficient of agreement was computed over all datasets and compared with that obtained from other methods. Results showed that the proposed method was within the top three among nine methods tested. Copyright ISPRS Numéro de notice : A2006-438 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2006.06.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2006.06.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28162
in ISPRS Journal of photogrammetry and remote sensing > vol 61 n° 1 (October 2006) . - pp 11 - 22[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-06071 SL Revue Centre de documentation Revues en salle Disponible Temporal influences on Landsat-5 thematic image in visible band / Y. Liu in International Journal of Remote Sensing IJRS, vol 27 n°15-16 (August 2006)
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