Descripteur
Termes IGN > mathématiques > statistique mathématique > probabilités > théorie des erreurs > erreur systématique
erreur systématiqueSynonyme(s)biaisVoir aussi |
Documents disponibles dans cette catégorie (388)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
Forest classification and impact of BIOMASS resolution on forest area and aboveground biomass estimation / Michael Schlund in International journal of applied Earth observation and geoinformation, vol 56 (April 2017)
[article]
Titre : Forest classification and impact of BIOMASS resolution on forest area and aboveground biomass estimation Type de document : Article/Communication Auteurs : Michael Schlund, Auteur ; Klaus Scipal, Auteur ; Malcolm W.J. Davidson, Auteur Année de publication : 2017 Article en page(s) : pp 65 - 76 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] bande P
[Termes IGN] base de données d'occupation du sol
[Termes IGN] biomasse aérienne
[Termes IGN] biomasse forestière
[Termes IGN] erreur systématique
[Termes IGN] estimation statistique
[Termes IGN] image radar moiréeRésumé : (auteur) The European Space Agency (ESA) is currently implementing the BIOMASS mission as 7th Earth Explorer satellite. BIOMASS will provide for the first time global forest aboveground biomass estimates based on P-band synthetic aperture radar (SAR) imagery. This paper addresses an often overlooked element of the data processing chain required to ensure reliable and accurate forest biomass estimates: accurate identification of forest areas ahead of the inversion of radar data into forest biomass estimates. The use of the P-band data from BIOMASS itself for the classification into forest and non-forest land cover types is assessed in this paper. For airborne data in tropical, hemi-boreal and boreal forests we demonstrate that classification accuracies from 90 up to 97% can be achieved using radar backscatter and phase information. However, spaceborne data will have a lower resolution and higher noise level compared to airborne data and a higher probability of mixed pixels containing multiple land cover types. Therefore, airborne data was reduced to 50 m, 100 m and 200 m resolution. The analysis revealed that about 50–60% of the area within the resolution level must be covered by forest to classify a pixel with higher probability as forest compared to non-forest. This results in forest omission and commission leading to similar forest area estimation over all resolutions. However, the forest omission resulted in a biased underestimated biomass, which was not equaled by the forest commission. The results underline the necessity of a highly accurate pre-classification of SAR data for an accurate unbiased aboveground biomass estimation. Numéro de notice : A2017-370 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.jag.2016.12.001 En ligne : https://doi.org/10.1016/j.jag.2016.12.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85789
in International journal of applied Earth observation and geoinformation > vol 56 (April 2017) . - pp 65 - 76[article]Performance evaluation of GNSS-TEC estimation techniques at the grid point in middle and low latitudes during different geomagnetic conditions / O. E. Abe in Journal of geodesy, vol 91 n° 4 (April 2017)
[article]
Titre : Performance evaluation of GNSS-TEC estimation techniques at the grid point in middle and low latitudes during different geomagnetic conditions Type de document : Article/Communication Auteurs : O. E. Abe, Auteur ; X. Otero Villamide, Auteur ; C. Paparini, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 409 - 417 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] champ géomagnétique
[Termes IGN] erreur systématique
[Termes IGN] Espagne
[Termes IGN] estimation statistique
[Termes IGN] étalonnage
[Termes IGN] évaluation
[Termes IGN] Ghana
[Termes IGN] latitude
[Termes IGN] performance
[Termes IGN] signal GNSS
[Termes IGN] teneur totale en électrons
[Termes IGN] traitement du signalRésumé : (auteur) Global Navigation Satellite Systems (GNSS) have become a powerful tool use in surveying and mapping, air and maritime navigation, ionospheric/space weather research and other applications. However, in some cases, its maximum efficiency could not be attained due to some uncorrelated errors associated with the system measurements, which is caused mainly by the dispersive nature of the ionosphere. Ionosphere has been represented using the total number of electrons along the signal path at a particular height known as Total Electron Content (TEC). However, there are many methods to estimate TEC but the outputs are not uniform, which could be due to the peculiarity in characterizing the biases inside the observables (measurements), and sometimes could be associated to the influence of mapping function. The errors in TEC estimation could lead to wrong conclusion and this could be more critical in case of safety-of-life application. This work investigated the performance of Ciraolo’s and Gopi’s GNSS-TEC calibration techniques, during 5 geomagnetic quiet and disturbed conditions in the month of October 2013, at the grid points located in low and middle latitudes. The data used are obtained from the GNSS ground-based receivers located at Borriana in Spain (40∘N, 0∘E; mid latitude) and Accra in Ghana (5.50∘N, −0.20∘E; low latitude). The results of the calibrated TEC are compared with the TEC obtained from European Geostationary Navigation Overlay System Processing Set (EGNOS PS) TEC algorithm, which is considered as a reference data. The TEC derived from Global Ionospheric Maps (GIM) through International GNSS service (IGS) was also examined at the same grid points. The results obtained in this work showed that Ciraolo’s calibration technique (a calibration technique based on carrier-phase measurements only) estimates TEC better at middle latitude in comparison to Gopi’s technique (a calibration technique based on code and carrier-phase measurements). At the same time, Gopi’s calibration was also found more reliable in low latitude than Ciraolo’s technique. In addition, the TEC derived from IGS GIM seems to be much reliable in middle-latitude than in low-latitude region. Numéro de notice : A2017-107 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0972-z En ligne : http://dx.doi.org/10.1007/s00190-016-0972-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84497
in Journal of geodesy > vol 91 n° 4 (April 2017) . - pp 409 - 417[article]Bias compensation for rational function model based on total least squares / Anzhu Yu in Photogrammetric record, vol 32 n° 157 (March - May 2017)
[article]
Titre : Bias compensation for rational function model based on total least squares Type de document : Article/Communication Auteurs : Anzhu Yu, Auteur ; Ting Jiang, Auteur ; Wenyue Guo, Auteur Année de publication : 2017 Article en page(s) : pp 48 - 60 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] analyse numérique
[Termes IGN] calcul d'erreur
[Termes IGN] compensation par moindres carrés
[Termes IGN] erreur aléatoire
[Termes IGN] erreur systématique
[Termes IGN] modèle par fonctions rationnelles
[Termes IGN] pondération
[Termes IGN] précision du positionnementRésumé : (auteur) When using the rational function model for the geometric orientation and geopositioning of satellite imagery, systematic bias compensation for vendor-provided rational polynomial coefficients (RPCs) is very important. Most existing bias-compensation models express systematic biases as a function of certain deterministic parameters, and least squares adjustment is used for estimating correction parameters. In this paper, the errors-in-variables model is introduced to take random errors in both the observation vector and the design matrix into consideration, based on a weighted total least squares adjustment. Experiments performed with two datasets demonstrate that the proposed method is reliable and the geopositioning accuracy improvement is better compared with a traditional least squares adjustment. Numéro de notice : A2017-197 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12183 En ligne : http://dx.doi.org/10.1111/phor.12183 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84871
in Photogrammetric record > vol 32 n° 157 (March - May 2017) . - pp 48 - 60[article]Estimation and analysis of Galileo differential code biases / Min Li in Journal of geodesy, vol 91 n° 3 (March 2017)
[article]
Titre : Estimation and analysis of Galileo differential code biases Type de document : Article/Communication Auteurs : Min Li, Auteur ; Yunbin Yuan, Auteur ; Ningbo Wang, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 279 - 293 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] combinaison au niveau des observations
[Termes IGN] constellation Galileo
[Termes IGN] données Galileo
[Termes IGN] données GPS
[Termes IGN] erreur systématique
[Termes IGN] estimation statistique
[Termes IGN] Galileo en mode différentiel
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] récepteur bifréquence
[Termes IGN] récepteur GNSS
[Termes IGN] signal GalileoMots-clés libres : Multi-GNSS Experiment (MGEX) Résumé : (Auteur) When sensing the Earth’s ionosphere using dual-frequency pseudorange observations of global navigation satellite systems (GNSS), the satellite and receiver differential code biases (DCBs) account for one of the main sources of error. For the Galileo system, limited knowledge is available about the determination and characteristic analysis of the satellite and receiver DCBs. To better understand the characteristics of satellite and receiver DCBs of Galileo, the IGGDCB (IGG, Institute of Geodesy and Geophysics, Wuhan, China) method is extended to estimate the satellite and receiver DCBs of Galileo, with the combined use of GPS and Galileo observations. The experimental data were collected from the Multi-GNSS Experiment network, covering the period of 2013–2015. The stability of both Galileo satellite and receiver DCBs over a time period of 36 months was thereby analyzed for the current state of the Galileo system. Good agreement of Galileo satellite DCBs is found between the IGGDCB-based DCB estimates and those from the German Aerospace Center (DLR), at the level of 0.22 ns. Moreover, high-level stability of the Galileo satellite DCB estimates is obtained over the selected time span (less than 0.25 ns in terms of standard deviation) by both IGGDCB and DLR algorithms. The Galileo receiver DCB estimates are also relatively stable for the case in which the receiver hardware device stays unchanged. It can also be concluded that the receiver DCB estimates are rather sensitive to the change of the firmware version and that the receiver antenna type has no great impact on receiver DCBs. Numéro de notice : A2017-066 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0962-1 En ligne : http://dx.doi.org/10.1007/s00190-016-0962-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84294
in Journal of geodesy > vol 91 n° 3 (March 2017) . - pp 279 - 293[article]On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames / Santiago Belda in Journal of geodesy, vol 91 n° 2 (February 2017)
[article]
Titre : On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames Type de document : Article/Communication Auteurs : Santiago Belda, Auteur ; Robert Heinkelmann, Auteur ; José M. Ferrándiz,, Auteur ; Tobias Nilsson, Auteur Année de publication : 2017 Article en page(s) : pp 135 - 149 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] erreur systématique
[Termes IGN] interférométrie à très grande base
[Termes IGN] International Earth Rotation Service
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] orientation de la Terre
[Termes IGN] repère de référence céleste
[Termes IGN] rotation de la Terre
[Termes IGN] série temporelleRésumé : (Auteur) Precise transformation between the celestial reference frames (CRF) and terrestrial reference frames (TRF) is needed for many purposes in Earth and space sciences. According to the Global Geodetic Observing System (GGOS) recommendations, the accuracy of positions and stability of reference frames should reach 1 mm and 0.1 mm year−1, and thus, the Earth Orientation Parameters (EOP) should be estimated with similar accuracy. Different realizations of TRFs, based on the combination of solutions from four different space geodetic techniques, and CRFs, based on a single technique only (VLBI, Very Long Baseline Interferometry), might cause a slow degradation of the consistency among EOP, CRFs, and TRFs (e.g., because of differences in geometry, orientation and scale) and a misalignment of the current conventional EOP series, IERS 08 C04. We empirically assess the consistency among the conventional reference frames and EOP by analyzing the record of VLBI sessions since 1990 with varied settings to reflect the impact of changing frames or other processing strategies on the EOP estimates. Our tests show that the EOP estimates are insensitive to CRF changes, but sensitive to TRF variations and unmodeled geophysical signals at the GGOS level. The differences between the conventional IERS 08 C04 and other EOP series computed with distinct TRF settings exhibit biases and even non-negligible trends in the cases where no differential rotations should appear, e.g., a drift of about 20 μas year−1in ypol when the VLBI-only frame VTRF2008 is used. Likewise, different strategies on station position modeling originate scatters larger than 150 μas in the terrestrial pole coordinates. Numéro de notice : A2017-061 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0944-3 En ligne : http://dx.doi.org/10.1007/s00190-016-0944-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84273
in Journal of geodesy > vol 91 n° 2 (February 2017) . - pp 135 - 149[article]Ambiguity resolved precise point positioning with GPS and BeiDou / Pan Li in Journal of geodesy, vol 91 n° 1 (January 2017)PermalinkGPS/BDS short-term ISB modelling and prediction / Nan Jiang in GPS solutions, vol 21 n° 1 (January 2017)PermalinkIs the Jason-2 DORIS oscillator also affected by the South Atlantic Anomaly? / Pascal Willis in Advances in space research, vol 58 n° 12 (15 December 2016)PermalinkAssessment of the accuracy of global geodetic satellite laser ranging observations and estimated impact on ITRF scale: estimation of systematic errors in LAGEOS observations 1993–2014 / Graham Appleby in Journal of geodesy, vol 90 n° 12 (December 2016)PermalinkA drift line bias estimator: ARMA-based filter or calibration method, and its application in BDS/GPS-based attitude determination / Zhang Liang in Journal of geodesy, vol 90 n° 12 (December 2016)PermalinkPrecise point positioning model using triple GNSS constellations: GPS, Galileo and BeiDou / Akram Afifi in Journal of applied geodesy, vol 10 n° 4 (December 2016)PermalinkRigorous strip adjustment of UAV-based laserscanning data including time-dependent correction of trajectory errors / Philipp Glira in Photogrammetric Engineering & Remote Sensing, PERS, vol 82 n° 12 (December 2016)PermalinkGenerating GPS satellite fractional cycle bias for ambiguity-fixed precise point positioning / Pan Li in GPS solutions, vol 20 n° 4 (October 2016)PermalinkQuantitative assessment of meteorological and tropospheric Zenith Hydrostatic Delay models / Di Zhang in Advances in space research, vol 58 n° 6 (September 2016)PermalinkPPP-RTK and inter-system biases: the ISB look-up table as a means to support multi-system PPP-RTK / Amir Khodabandeh in Journal of geodesy, vol 90 n° 9 (September 2016)Permalink