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Precise point positioning with ATOMIUM using IGS orbit and clock products: first results / Quentin Baire in Bulletin of geodesy and geomatics BGG, vol 69 n° 2 - 3 (December 2010)
[article]
Titre : Precise point positioning with ATOMIUM using IGS orbit and clock products: first results Type de document : Article/Communication Auteurs : Quentin Baire, Auteur ; Carine Bruyninx, Auteur ; P. Defraigne, Auteur ; Juliette Legrand, Auteur Année de publication : 2010 Article en page(s) : pp 391 - 400 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Atomium
[Termes IGN] positionnement ponctuel précis
[Termes IGN] propagation troposphérique
[Termes IGN] station de réception
[Termes IGN] traitement de données GNSS
[Termes IGN] transformation de HelmertRésumé : (Auteur) In this paper, we investigate the quality of the station positions determined by Precise Point Positioning using ATOMIUM. For that purpose, the IGS orbits and clock files are considered as a priori information while ATOMIUM estimates daily station positions, hourly tropospheric zenith path delays and epoch-wise station clock synchronization errors with respect to the IGS time. In addition to its very fast operation (a daily run takes about 5 seconds by station), the mean weekly position repeatability obtained with ATOMIUM is at the level of 3.9 mm for the north, 2.4 mm for the east and 6.8 mm for the up component. If in addition, a Helmert transformation is performed to more reliably express the solution in the IGS05, then the mean weekly station position repeatabilities reach 3.1 mm for the north, 1.9 mm for the east and 5.7 mm for the up component, i.e. similar to what is presently obtained with the Bernese. Numéro de notice : A2010-595 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31339
in Bulletin of geodesy and geomatics BGG > vol 69 n° 2 - 3 (December 2010) . - pp 391 - 400[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 013-2010021 RAB Revue Centre de documentation En réserve L003 Disponible Rapid re-convergences to ambiguity-fixed solutions in precise point positioning / J. Geng in Journal of geodesy, vol 84 n° 12 (December 2010)
[article]
Titre : Rapid re-convergences to ambiguity-fixed solutions in precise point positioning Type de document : Article/Communication Auteurs : J. Geng, Auteur ; X. Meng, Auteur ; A. Dodson, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : 10 p. ; pp 705 - 714 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] ambiguïté entière
[Termes IGN] convergence
[Termes IGN] correction ionosphérique
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement ponctuel précis
[Termes IGN] propagation ionosphérique
[Termes IGN] résolution d'ambiguïté
[Termes IGN] Suisse
[Termes IGN] temps réelRésumé : (Auteur) Integer ambiguity resolution at a single receiver can be achieved if the fractional-cycle biases are separated from the ambiguity estimates in precise point positioning (PPP). Despite the improved positioning accuracy by such integer resolution, the convergence to an ambiguity-fixed solution normally requires a few tens of minutes. Even worse, these convergences can repeatedly occur on the occasion of loss of tracking locks for many satellites if an open sky-view is not constantly available, consequently totally destroying the practicability of real-time PPP. In this study, in case of such re-convergences, we develop a method in which ionospheric delays are precisely predicted to significantly accelerate the integer ambiguity resolution. The effectiveness of this method consists in two aspects: first, wide-lane ambiguities can be rapidly resolved using the ionosphere-corrected wide-lane measurements, instead of the noisy Melbourne–Wübbena combination measurements; second, narrow-lane ambiguity resolution can be accelerated under the tight constraints derived from the ionosphere-corrected unambiguous wide-lane measurements. In the test at 90 static stations suffering from simulated total loss of tracking locks, 93.3 and 95.0% of re-convergences to wide-lane and narrow-lane ambiguity resolutions can be achieved within five epochs of 1-Hz measurements, respectively, even though the time latency for the predicted ionospheric delays is up to 180 s. In the test at a mobile van moving in a GPS-adverse environment where satellite number significantly decreases and cycle slips frequently occur, only when the predicted ionospheric delays are applied can the rate of ambiguity-fixed epochs be dramatically improved from 7.7 to 93.6% of all epochs. Therefore, this method can potentially relieve the unrealistic requirement of a continuous open sky-view by most PPP applications and improve the practicability of real-time PPP. Numéro de notice : A2010-558 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0404-4 Date de publication en ligne : 14/08/2010 En ligne : https://doi.org/10.1007/s00190-010-0404-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30750
in Journal of geodesy > vol 84 n° 12 (December 2010) . - 10 p. ; pp 705 - 714[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-02010121 SL Revue Centre de documentation Revues en salle Disponible 266-2010121 SL Revue Centre de documentation Revues en salle Disponible Effect of corn on C-an L-band radar backscatter: a correction method for soil moisture retrieval / A. Joseph in Remote sensing of environment, vol 114 n° 11 (15/11/2010)
[article]
Titre : Effect of corn on C-an L-band radar backscatter: a correction method for soil moisture retrieval Type de document : Article/Communication Auteurs : A. Joseph, Auteur ; R. Van Der Velde, Auteur ; P. O'neill, Auteur ; R. Lang, Auteur ; T. Gish, Auteur Année de publication : 2010 Article en page(s) : pp 2417 - 2430 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] angle d'incidence
[Termes IGN] bande C
[Termes IGN] bande L
[Termes IGN] biomasse
[Termes IGN] humidité du sol
[Termes IGN] maïs (céréale)
[Termes IGN] polarimétrie radar
[Termes IGN] rétrodiffusion
[Termes IGN] teneur en eau de la végétationRésumé : (Auteur) This paper discusses the effects of vegetation on C- (4.75 GHz) and L- (1.6 GHz) band backscattering (Ó) measured throughout a growth cycle at incidence angles of 15, 35 and 55°. The utilized Ó data set was collected by a truck mounted scatterometer over a corn field and is supported by a comprehensive set of ground measurements, including soil moisture and vegetation biomass. Comparison of Ó measurement against simulations by the Integral Equation Method (IEM) surface scattering model (Fung et al., 1992) shows that the Ó measurements are dominated either by an attenuated soil return or by scattering from vegetation depending on the antenna configuration and growth stage. Further, the measured Ó is found to be sensitive to soil moisture even at peak biomass and large incidence angles, which is attributed to scattering along the soil-vegetation pathway. For the simulation of C-band Ó and the retrieval of soil moisture two methods have been applied, which are the semi-empirical water cloud model (Attema & Ulaby, 1978) and a novel method. This alternative method uses the empirical relationships between the vegetation water content (W) and the ratio of the bare soil and the measured Ó to correct for vegetation. It is found that this alternative method is superior in reproducing the measured Ó as well as retrieving soil moisture. The highest retrieval accuracies are obtained at a 35° incidence angle leading to RMSD's of 0.044 and 0.037 m3 m- 3 for the HH and VV-polarization, respectively. In addition, the sensitivity of these soil moisture retrievals to W and surface roughness parameter uncertainties is investigated. Numéro de notice : A2010-400 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2010.05.017 En ligne : https://doi.org/10.1016/j.rse.2010.05.017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30593
in Remote sensing of environment > vol 114 n° 11 (15/11/2010) . - pp 2417 - 2430[article]Use of high-resolution satellite imagery in an integrated model to predict the distribution of shade coffee tree hybrid zones / C. Gomez in Remote sensing of environment, vol 114 n° 11 (15/11/2010)
[article]
Titre : Use of high-resolution satellite imagery in an integrated model to predict the distribution of shade coffee tree hybrid zones Type de document : Article/Communication Auteurs : C. Gomez, Auteur ; M. Mangeas, Auteur ; Marcel Petit, Auteur ; Christina Corbane, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 2731 - 2744 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] analyse texturale
[Termes IGN] carte thématique
[Termes IGN] classification dirigée
[Termes IGN] classification par arbre de décision
[Termes IGN] classification par réseau neuronal
[Termes IGN] Coffea (genre)
[Termes IGN] couvert forestier
[Termes IGN] image à haute résolution
[Termes IGN] image panchromatique
[Termes IGN] image Quickbird
[Termes IGN] modèle numérique de surface
[Termes IGN] Nouvelle-Calédonie
[Termes IGN] ombre
[Termes IGN] pansharpening (fusion d'images)
[Termes IGN] prédictionRésumé : (Auteur) In New Caledonia (21°S, 165°E), shade-grown coffee plantations were abandoned for economic reasons in the middle of the 20th century. Coffee species (Coffea arabica, C. canephora and C. liberica) were introduced from Africa in the late 19th century, they survived in the wild and spontaneously cross-hybridized. Coffee species were originally planted in native forest in association with leguminous trees (mostly introduced species) to improve their growth. Thus the canopy cover over rustic shade coffee plantations is heterogeneous with a majority of large crowns, attributed to leguminous trees. The aim of this study was to identify suitable areas for coffee inter-specific hybridization in New Caledonia using field based environmental parameters and remotely sensed predictors. Due to the complex structure of tropical vegetation, remote sensing imagery needs to be spatially accurate and to have the appropriate bands for monitoring vegetation cover. Quickbird panchromatic (black and white) imagery at 0.6 to 0.7 m spatial resolutions and multispectral imagery at 2.4 m spatial resolution were pansharpened and used for this study. The two most suitable remotely sensed indicators, canopy heterogeneity and tree crown size, were acquired by the sequential use of tree crown detection (neural network), image processing (such as textural analysis) and classification. All models were supervised and trained on learning data determined by human expertise. The final model has two remotely sensed indicators and three physical parameters based on the Digital Elevation Model: elevation, slope and water flow accumulation. Using these five predictive variables as inputs, two modelling methods, a decision tree and a neural network, were implemented. The decision tree, which showed 96.9% accuracy on the test set, revealed the involvement of ecological parameters in the hybridization of Coffea species. We showed that hybrid zones could be characterized by combinations of modalities, underlining the complexity of the environment concerned. For instance, forest heterogeneity and large crown size, steep slopes (> 53.5%) and elevation between 194 and 429 m asl, are favourable factors for Coffea inter-specific hybridization. The application of the neural network on the whole area gave a predictive map that distinguished the most suitable areas by means of a nonlinear continuous indicator. The map provides a confidence level for each area. The most favourable areas were geographically localized, providing a clue for the detection and conservation of favourable areas for Coffea species neo-diversity. Numéro de notice : A2010-402 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2010.06.007 En ligne : https://doi.org/10.1016/j.rse.2010.06.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30595
in Remote sensing of environment > vol 114 n° 11 (15/11/2010) . - pp 2731 - 2744[article]A low-cost multi-sensoral mobile mapping system and its feasibility for tree measurements / Anttoni Jaakkola in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 6 (November - December 2010)
[article]
Titre : A low-cost multi-sensoral mobile mapping system and its feasibility for tree measurements Type de document : Article/Communication Auteurs : Anttoni Jaakkola, Auteur ; Antero Kukko, Auteur ; X. Yu, Auteur ; Juha Hyyppä, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 514 - 522 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] arbre (flore)
[Termes IGN] capteur aérien
[Termes IGN] chambre DTC
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] drone
[Termes IGN] géoréférencement direct
[Termes IGN] GPS-INS
[Termes IGN] lasergrammétrie
[Termes IGN] lidar topographique
[Termes IGN] rayonnement infrarouge thermique
[Termes IGN] semis de points
[Termes IGN] spectromètre
[Termes IGN] système de numérisation mobile
[Termes IGN] télémètre laser aéroporté
[Termes IGN] télémétrie laser aéroportéRésumé : (Auteur) This paper presents a novel low-cost mini-UAV-based laser scanning system, which is also capable of performing car-based mobile mapping. The quality of the system and its feasibility for tree measurements was tested using the system’s laser scanner. The system was constructed as a modular measurement system consisting of a number of measurement instruments: a GPS/IMU positioning system, two laser scanners, a CCD camera, a spectrometer and a thermal camera. An Ibeo Lux and a Sick LMS151 profile laser were integrated into the system to provide dense point clouds; intensities of the reflected echoes can also be obtained with the Sick LMS. In our tests, when using a car as a platform, the pole-type object extraction algorithm which was developed resulted in 90% completeness and 86% correctness. The heights of pole-type objects were obtained with a bias of -1.6 cm and standard deviation of 5.4 cm. Using a mini-UAV as the platform, the standard deviation of individual tree heights was about 30 cm. Also, a digital elevation model extraction was tested with the UAV data, resulting in a height offset of about 3.1 cm and a standard deviation of 9.2 cm. With a multitemporal point cloud, we demonstrated a method to derive the biomass change of a coniferous tree with an R2 value of 0.92. The proposed system is capable of not only recording point cloud data giving the geometry of the objects, but also simultaneously collecting image data, including overlapping images and the intensity of laser backscatter, as well as hyperspectral and thermal data. Therefore we believe that the system is feasible for new algorithm and concept development and for basic research, especially when data is recorded multitemporally. Numéro de notice : A2010-484 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2010.08.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2010.08.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30677
in ISPRS Journal of photogrammetry and remote sensing > vol 65 n° 6 (November - December 2010) . - pp 514 - 522[article]Réservation
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