Descripteur
Documents disponibles dans cette catégorie (1523)
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
GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions / C. Brunini in Journal of geodesy, vol 84 n° 5 (May 2010)
[article]
Titre : GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions Type de document : Article/Communication Auteurs : C. Brunini, Auteur ; F. Azpilicueta, Auteur Année de publication : 2010 Article en page(s) : pp 293 - 304 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] erreur systématique
[Termes IGN] ionosphère
[Termes IGN] positionnement par GPS
[Termes IGN] teneur totale en électrons
[Termes IGN] traitement de données GNSSRésumé : (Auteur) The use of observations from the Global Positioning System (GPS) has significantly impacted the study of the ionosphere. As it is widely known, dual-frequency GPS observations can provide very precise estimation of the slant Total Electron Content (sTEC—the linear integral of the electron density along a ray-path) and that the precision level is bounded by the carrier-phase noise and multi-path effects on both frequencies. Despite its precision, GPS sTEC estimations can be systematically affected by errors in the estimation of the satellites and receivers by Inter-Frequency Biases (IFB) that are simultaneously determined with the sTEC. Thus, the ultimate accuracy of the GPS sTEC estimation is determined by the errors with which the IFBs are estimated. This contribution attempts to assess the accuracy of IFBs estimation techniques based on the single layer model for different ionospheric regions (low, mid and high magnetic latitude); different seasons (summer and winter solstices and spring and autumn equinoxes); different solar activity levels (high and low); and different geomagnetic conditions (quiet and very disturbed). The followed strategy relies upon the generation of a synthetic data set free of IFB, multi-path, measurement noise and of any other error source. Therefore, when a data set with such properties is used as the input of the IFB estimation algorithms, any deviation from zero on the estimated IFBs should be taken as indications of the errors introduced by the estimation technique. The truthfulness of this assessment work is warranted by the fact that the synthetic data sets resemble, as realistically as possible, the different conditions that may happen in the real ionosphere. The results of this work show that during the high solar activity period the accuracy for the estimated sTEC is approximately of 110 TECu for the low geomagnetic region and of 12.2 TECu for the mid-latitude. During low solar activity the accuracy can be assumed to be in the order of 12 TECu. For the geomagnetic high-disturbed period, the results show that the accuracy is degraded for those stations located over the region where the storm has the strongest impact, but for those stations over regions where the storm has a moderate effect, the accuracy is comparable to that obtained in the quiet period. Numéro de notice : A2010-182 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0367-5 Date de publication en ligne : 29/01/2010 En ligne : https://doi.org/10.1007/s00190-010-0367-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30377
in Journal of geodesy > vol 84 n° 5 (May 2010) . - pp 293 - 304[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2010051 SL Revue Centre de documentation Revues en salle Disponible New results in airborne vector gravimetry using strapdown INS/DGPS / M. Senobari in Journal of geodesy, vol 84 n° 5 (May 2010)
[article]
Titre : New results in airborne vector gravimetry using strapdown INS/DGPS Type de document : Article/Communication Auteurs : M. Senobari, Auteur Année de publication : 2010 Article en page(s) : pp 277 - 291 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] estimation statistique
[Termes IGN] GPS en mode différentiel
[Termes IGN] GPS-INS
[Termes IGN] gravimétrie aérienneRésumé : (Auteur) A method for airborne vector gravimetry has been developed. The method is based on developing the error dynamics equations of the INS in the inertial frame where the INS system errors are estimated in a wave estimator using inertial GPS position as update. Then using the error-corrected INS acceleration and the GPS acceleration in the inertial frame, the gravity disturbance vector is extracted. In the paper, the focus is on the improvement of accuracy for the horizontal components of the airborne gravity vector. This is achieved by using a decoupled model in the wave estimator and decorrelating the gravity disturbance from the INS system errors through the estimation process. The results of this method on the real strapdown INS/DGPS data are promising. The internal accuracy of the horizontal components of the estimated gravity disturbance for repeated airborne lines is comparable with the accuracy of the down component and is about 4–8 mGal. Better accuracy (2–4 mGal) is achieved after applying a wave-number correlation filter (WCF) to the parallel lines of the estimated airborne gravity disturbances. Numéro de notice : A2010-181 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0366-6 Date de publication en ligne : 01/03/2010 En ligne : https://doi.org/10.1007/s00190-010-0366-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30376
in Journal of geodesy > vol 84 n° 5 (May 2010) . - pp 277 - 291[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 266-2010051 SL Revue Centre de documentation Revues en salle Disponible Estimating crown base height for Scots pine by means of the 3D geometry of airborne laser scanning data / Jari Vauhkonen in International Journal of Remote Sensing IJRS, vol 31 n° 5 (March 2010)
[article]
Titre : Estimating crown base height for Scots pine by means of the 3D geometry of airborne laser scanning data Type de document : Article/Communication Auteurs : Jari Vauhkonen, Auteur Année de publication : 2010 Conférence : Silvilaser 2008, 8th international conference on Lidar applications in forest assessment and inventory 17/09/2008 19/09/2008 Edimbourg Royaume-Uni Proceedings Taylor&Francis Article en page(s) : pp 1213 - 1226 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] croissance des arbres
[Termes IGN] données laser
[Termes IGN] données localisées 3D
[Termes IGN] estimation statistique
[Termes IGN] géomètrie algorithmique
[Termes IGN] hauteur des arbres
[Termes IGN] houppier
[Termes IGN] lasergrammétrie
[Termes IGN] modélisation 3D
[Termes IGN] Pinus sylvestris
[Termes IGN] régression linéaire
[Termes IGN] sylviculture
[Termes IGN] télémétrie laser aéroporté
[Termes IGN] triangulation de DelaunayRésumé : (Auteur) Crown base height (CBH) is an important factor in relation to several characteristics of the tree stock. This paper introduces approaches for estimating tree-level CBH from airborne laser scanning (ALS) data that make use of features of computational geometry. For that purpose, the concepts of Delaunay triangulations and alpha shapes were applied and compared with approaches based on analysing return frequencies and predicting CBH by linear regression. These approaches were evaluated using test data on a total of 185 Scots pine trees, of which 136 were of sawlog size, that were detected and delineated from ALS data with a density of approximately 4 returns m-2. The results suggest that variables based on the frequencies of crown returns within predefined height bins are the most accurate for estimating CBH. By combining the best CBH estimate with the estimated tree height in linear regression, a root mean squared error (RMSE) of 1.4 m (14%) was achieved when all study trees were considered. The estimation was generally less accurate for the trees smaller than those of sawlog size. Although the accuracy of estimating CBH is lower using the three-dimensional (3D) geometry approaches presented here, they are considered to have potential for further development. Numéro de notice : A2010-252 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160903380615 En ligne : https://doi.org/10.1080/01431160903380615 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30446
in International Journal of Remote Sensing IJRS > vol 31 n° 5 (March 2010) . - pp 1213 - 1226[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-2010031 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Consistency of accuracy assessment indices for soft classification: simulation analysis / J. Chen in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 2 (March - April 2010)
[article]
Titre : Consistency of accuracy assessment indices for soft classification: simulation analysis Type de document : Article/Communication Auteurs : J. Chen, Auteur ; X. Zhu, Auteur ; H. Imura, Auteur ; X. Chen, Auteur Année de publication : 2010 Article en page(s) : pp 156 - 164 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] analyse comparative
[Termes IGN] classification
[Termes IGN] erreur moyenne quadratique
[Termes IGN] estimation de précision
[Termes IGN] Kappa de Cohen
[Termes IGN] matrice de confusion
[Termes IGN] niveau d'analyse
[Termes IGN] précision cartographique
[Termes IGN] précision décimétrique
[Termes IGN] simulationRésumé : (Auteur) Accuracy assessment plays a crucial role in the implementation of soft classification. Even though many indices of accuracy assessment for soft classification have been proposed, the consistencies among these indices are not clear, and the impact of sample size on these consistencies has not been investigated. This paper examines two kinds of indices: map-level indices, including root mean square error (rmse), kappa, and overall accuracy (oa) from the sub-pixel confusion matrix (SCM); and category-level indices, including crmse, user accuracy (ua) and producer accuracy (pa). A careful simulation was conducted to investigate the consistency of these indices and the effect of sample size. The major findings were as follows: (1) The map-level indices are highly consistent with each other, whereas the category-level indices are not. (2) The consistency among map-level and category-level indices becomes weaker when the sample size decreases. (3) The rmse is more affected by error distribution among classes than are kappa and oa. Based on these results, we recommend that rmse can be used for map-level accuracy due to its simplicity, although kappa and oa may be better alternatives when the sample size is limited because the two indices are affected less by the error distribution among classes. We also suggest that crmse should be provided when map users are not concerned about the error source, whereas ua and pa are more useful when the complete information about different errors is required. The results of this study will be of benefit to the development and application of soft classifiers. Copyright ISPRS Numéro de notice : A2010-090 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2009.10.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2009.10.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30286
in ISPRS Journal of photogrammetry and remote sensing > vol 65 n° 2 (March - April 2010) . - pp 156 - 164[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2010021 SL Revue Centre de documentation Revues en salle Disponible Detecting negative spatial autocorrelation in georeferenced random variables / Daniel A. Griffith in International journal of geographical information science IJGIS, vol 24 n°3-4 (march 2010)
[article]
Titre : Detecting negative spatial autocorrelation in georeferenced random variables Type de document : Article/Communication Auteurs : Daniel A. Griffith, Auteur ; Guiseppe Arbia, Auteur Année de publication : 2010 Article en page(s) : pp 417 - 437 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique
[Termes IGN] agrégation spatiale
[Termes IGN] autocorrélation spatiale
[Termes IGN] distribution spatiale
[Termes IGN] inférence statistique
[Termes IGN] régression
[Termes IGN] variable aléatoire
[Termes IGN] variable régionalisée
[Termes IGN] vecteur propreRésumé : (Auteur) Negative spatial autocorrelation refers to a geographic distribution of values, or a map pattern, in which the neighbors of locations with large values have small values, the neighbors of locations with intermediate values have intermediate values, and the neighbors of locations with small values have large values. Little is known about negative spatial autocorrelation and its consequences in statistical inference in general, and regression-based inference in particular, with spatial researchers to date concentrating mostly on understanding the much more frequently encountered case of positive spatial autocorrelation. What are the spatial contexts within which negative spatial autocorrelation should be readily found? What are its inferential consequences for regression models? This paper presents selected empirical examples of negative spatial autocorrelation, adding to the slowly growing literature about this phenomenon. Copyright Taylor & Francis Numéro de notice : A2010-143 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810902832591 En ligne : http://dx.doi.org/10.1080/13658810902832591 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30338
in International journal of geographical information science IJGIS > vol 24 n°3-4 (march 2010) . - pp 417 - 437[article]Réservation
Réserver ce documentExemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 079-2010022 RAB Revue Centre de documentation En réserve L003 Disponible 079-2010021 RAB Revue Centre de documentation En réserve L003 Disponible Home energy assessment technologies / G. Hay in GIM international, vol 24 n° 3 (March 2010)PermalinkHomogeneous zenith total delay parameter estimation from European permanent GNSS sites / Wolfgang Söhne in Bulletin of geodesy and geomatics BGG, vol 69 n° 1 (March 2010)PermalinkSpatial data infrastructures as complex adaptative systems / Lucasz Grus in International journal of geographical information science IJGIS, vol 24 n°3-4 (march 2010)PermalinkA bias-free geodetic boundary value problem approach to height datum unification / Alireza A. Ardalan in Journal of geodesy, vol 84 n° 2 (February 2010)PermalinkAlternative methodologies for the internal quality control of parallele LIDAR strips / A. Habib in IEEE Transactions on geoscience and remote sensing, vol 48 n° 1 Tome 1 (January 2010)PermalinkBiais et dérives dans l'altimétrie satellitale à partir de comparaisons avec des marégraphes co-localisés avec des stations GPS / Médéric Gravelle (2010)PermalinkDétection d'empreintes de bâtiments dans un modèle numérique d'élévation : une approche énergétique / Olivier Tournaire (2010)PermalinkEtude des erreurs systématiques liées à la détermination du géocentre par les mesures DORIS / Marie-Line Gobinddass (2010)PermalinkIn-flight quality assessment and data processing for airborne laser scanning / Philipp Schaer (2010)PermalinkMathématiques pour le traitement du signal / M. Bergounioux (2010)Permalink