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GRACE-FO precise orbit determination and gravity recovery / Z. Kang in Journal of geodesy, vol 94 n° 9 (September 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 9 (September 2020) . - n° 85 Titre : GRACE-FO precise orbit determination and gravity recovery Type de document : Article/Communication Auteurs : Z. Kang, Auteur ; S. Bettadpur, Auteur ; P. Nagel, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : n° 85 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] bande K [Termes IGN] champ de pesanteur terrestre [Termes IGN] données GRACE [Termes IGN] double différence [Termes IGN] interféromètre au laser [Termes IGN] orbite précise [Termes IGN] orbitographie Résumé : (auteur) The gravity recovery and climate experiment follow-on (GRACE-FO) satellites, launched in May of 2018, are equipped with geodetic quality GPS receivers for precise orbit determination (POD) and gravity recovery. The primary objective of the GRACE-FO mission is to map the time-variable and mean gravity field of the Earth. To achieve this goal, both GRACE-FO satellites are additionally equipped with a K-band ranging (KBR) system, accelerometers and star trackers. Data processing strategies, data weighting approaches and impacts of observation types and rates are investigated in order to determine the most efficient approach for processing GRACE-FO multi-type data for precise orbit determination and gravity recovery. Two GPS observation types, un-differenced (UD) and double-differenced (DD) observations in general can be used for GPS-based POD and gravity recovery. The GRACE-FO KBR observations are mainly used for gravity recovery, but they can be also used for POD to improve the relative orbit accuracy. The main purpose of this paper is to study the impacts of the DD, UD and KBR observations on GRACE-FO POD and gravity recovery. The precise orbit accuracy is assessed using several tests, which include analysis of orbital fits, satellite laser ranging residuals, KBR range residuals and orbit comparisons. The gravity recovery is validated by comparing different gravity solutions through coefficient-wise comparison, degree difference variances and water height variations over the whole Earth and selected area and river basins. Numéro de notice : A2020-542 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01414-3 Date de publication en ligne : 16/08/2020 En ligne : https://doi.org/10.1007/s00190-020-01414-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95744 [article]

An automatic mosaicking method for building facade texture mapping using a monocular close-range image sequence / Z. Kang in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 3 (May - June 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 3 (May - June 2010) . - pp 282 - 293 Titre : An automatic mosaicking method for building facade texture mapping using a monocular close-range image sequence Type de document : Article/Communication Auteurs : Z. Kang, Auteur ; L. Zhang, Auteur ; Sisi Zlatanova, Auteur ; J. Li, Auteur Année de publication : 2010 Article en page(s) : pp 282 - 293 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie terrestre [Termes IGN] correction géométrique [Termes IGN] étalonnage de capteur (imagerie) [Termes IGN] façade [Termes IGN] image terrestre [Termes IGN] mosaïquage d'images [Termes IGN] photogrammétrie métrologique [Termes IGN] séquence d'images [Termes IGN] texturage Résumé : (Auteur) This paper presents an automatic mosaicking method for generating building facade textures from a monocular close-range digital image sequence. The process begins with the computation of the camera parameters (except the coordinates of the projective center), which are determined by combining vanishing point geometry with constraints of a straight line bundle as well as prior information of parallel lines in object space. The raw images are later rectified for the purpose of eliminating their salient geometric distortion. Next, automatic retrieval of the relevant image segment is implemented using the detecting range variance by means of the histogram of projective differences between the corresponding points for each of the facades from the raw image sequence. A strip model of the least-squares adjustment, which is similar to the strip block adjustment in aerial triangulation, is employed to determine the spatial alignment of each of the image segments in order to generate the facade textures from the relevant image segments. Afterwards, the entire building facade texture is mosaicked by ortho-image generation. Two refining strategies are proposed to optimize the mosaic result. One is refining the mosaic region where corresponding points are difficult to match but plenty of horizontal lines are available, and the constraint of corresponding horizontal lines is introduced to implement this process. The other strategy is to refine the unsatisfactory mosaic region by densifying the corresponding points by means of the spatial alignment of the relevant image segment computed by the strip method. The experimental results indicate that this method is widely applicable and compares well with other reported approaches with regard to automation level and applicability, for uncalibrated images as well as images with large geometric distortions. Numéro de notice : A2010-177 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2009.11.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2009.11.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30372 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-2010031	SL	Revue	Centre de documentation	Revues en salle	Disponible

Geocenter variations derived from GPS tracking of the GRACE satellites / Z. Kang in Journal of geodesy, vol 83 n° 10 (October 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 10 (October 2009) . - pp 895 - 901 Titre : Geocenter variations derived from GPS tracking of the GRACE satellites Type de document : Article/Communication Auteurs : Z. Kang, Auteur ; B. Tapley, Auteur ; J. Chen, Auteur ; John Ries, Auteur ; S. Bettadpur, Auteur Année de publication : 2009 Article en page(s) : pp 895 - 901 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] géocentre [Termes IGN] GRACE [Termes IGN] orbite basse [Termes IGN] orbitographie par GNSS [Termes IGN] poursuite de satellite Résumé : (Auteur) Two 4.5-year sets of daily geocenter variations have been derived from GPS-LEO (Low-Earth Orbiter) tracking of the GRACE (Gravity Recovery And Climate Experiment) satellites. The twin GRACE satellites, launched in March 2002, are each equipped with a BlackJack global positioning system (GPS) receiver for precise orbit determination and gravity recovery. Since launch, there have been significant improvements in the background force models used for satellite orbit determination, most notably the model for the geopotential, which has resulted in significant improvements to the orbit determination accuracy. The purpose of this paper is to investigate the potential for determining seasonal (annual and semiannual) geocenter variations using GPS-LEO tracking data from the GRACE twin satellites. Internal comparison between the GRACE-A and GRACE-B derived geocenter variations shows good agreement. In addition, the annual and semiannual variations of geocenter motions determined from this study have been compared with other space geodetic solutions and predictions from geophysical models. The comparisons show good agreement except for the phase of the z-translation component. Copyright Springer Numéro de notice : A2009-428 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0307-4 En ligne : https://doi.org/10.1007/s00190-009-0307-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30059 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09091	SL	Revue	Centre de documentation	Revues en salle	Disponible

Precise orbit determination for the GRACE mission using only GPS data / Z. Kang in Journal of geodesy, vol 80 n° 6 (September 2006)  

Public [article]  inJournal of geodesy > vol 80 n° 6 (September 2006) . - pp 322 - 331 Titre : Precise orbit determination for the GRACE mission using only GPS data Type de document : Article/Communication Auteurs : Z. Kang, Auteur ; B. Tapley, Auteur ; S. Bettadpur, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 322 - 331 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] GRACE [Termes IGN] orbitographie par GNSS [Termes IGN] positionnement par GPS [Termes IGN] télémétrie laser sur satellite Résumé : (Auteur) The GRACE (gravity recovery and climate experiment) satellites, launched in March 2002, are each equipped with a BlackJack GPS onboard receiver for precise orbit determination and gravity field recovery. Since launch, there have been significant improvements in the background force models used for satellite orbit determination, most notably the model for the geopotential. This has resulted in significant improvements to orbit accuracy for very low altitude satellites. The purpose of this paper is to investigate how well the orbits of the GRACE satellites (about 470 km in altitude) can currently be determined using only GPS data and based on the current models and methods. The orbit accuracy is assessed using a number of tests, which include analysis of orbit fits, orbit overlaps, orbit connecting points, satellite Laser ranging residuals and K-band ranging (KBR) residuals. We show that 1-cm radial orbit accuracy for the GRACE satellites has probably been achieved. These precise GRACE orbits can be used for such purposes as improving gravity recovery from the GRACE KBR data and for atmospheric profiling, and they demonstrate the quality of the background force models being used. Copyright Springer Numéro de notice : A2006-417 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0073-5 En ligne : https://doi.org/10.1007/s00190-006-0073-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28141 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-06081	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-06082	RAB	Revue	Centre de documentation	En réserve L003	Disponible