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Uncertainty analysis for soil-terrain models / T.F.A. Bishop in International journal of geographical information science IJGIS, vol 20 n° 2 (february 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 2 (february 2006) . - pp 117 - 134 Titre : Uncertainty analysis for soil-terrain models Type de document : Article/Communication Auteurs : T.F.A. Bishop, Auteur ; B. Minasny, Auteur ; A.B. Mcbratney, Auteur Année de publication : 2006 Article en page(s) : pp 117 - 134 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Information géographique [Termes IGN] Argile [Termes IGN] écart moyen [Termes IGN] écart type [Termes IGN] incertitude de position [Termes IGN] lissage de données [Termes IGN] méthode de Monte-Carlo [Termes IGN] modèle numérique de terrain [Termes IGN] pédologie locale [Termes IGN] positionnement par GPS [Termes IGN] qualité des données Résumé : (Auteur) The aim of the study was to examine how robust soil-terrain models are to uncertainty in the source elevation data. The study site was a 74ha agricultural field in Australia. A global positioning system was used to measure elevation and the uncertainty of the measurement, therefore allowing maps of elevation and its uncertainty to be created. Monte-Carlo simulation with a modified version of Latin Hypercube Sampling was used to create 100 realizations of a slope map. Clay content was measured at 111 sites, and kriging with external drift was used to map clay content where each slope realization was used as a secondary information source. Maps of the mean and standard deviation of clay content across all realizations were created. The standard deviations of clay content were generally small «4dagkg-1) and in most parts of the field less than the analytical accuracy of the hydrometer method which was used to measure soil clay content in the laboratory. The values in the map of elevation uncertainty were multiplied by 5 and the entire error propagation process was repeated to create a second set of 100 realizations of the clay content. The ratio of the uncertainty in the original DEM was 5:1 when compared with that in the perturbed DEM, i.e. it was multiplied by 5. The ratio between the standard deviation in the two clay-content maps was 3.79: 1, which indicates a reduction in uncertainty through the modelling process. The results showed that the soil-terrain model performs well for the study area, and it is not very sensitive to DEM errors. We conclude that input uncertainty tests as shown in this study should accompany soil mapping studies where secondary information is used in the prediction model. Numéro de notice : A2006-063 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810500287073 En ligne : https://doi.org/10.1080/13658810500287073 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27790 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Error-sensitive historical GIS: Identifying areal interpolation errors in time-series data / I.N. Gregory in International journal of geographical information science IJGIS, vol 20 n° 2 (february 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 2 (february 2006) . - pp 135 - 152 Titre : Error-sensitive historical GIS: Identifying areal interpolation errors in time-series data Type de document : Article/Communication Auteurs : I.N. Gregory, Auteur ; P.S. Ell, Auteur Année de publication : 2006 Article en page(s) : pp 135 - 152 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes d'information géographique [Termes IGN] analyse diachronique [Termes IGN] données statistiques [Termes IGN] historique des données [Termes IGN] interpolation spatiale [Termes IGN] série temporelle [Termes IGN] système d'information géographique Résumé : (Auteur) Historical GIS has the potential to re-invigorate our use of statistics from historical censuses and related sources. In particular, areal interpolation can be used to create long-run time-series of spatially detailed data that will enable us to enhance significantly our understanding of geographical change over periods of a century or more. The difficulty with areal interpolation, however, is that the data that it generates are estimates which will inevitably contain some error. This paper describes a technique that allows the automated identification of possible errors at the level of the individual data values. Numéro de notice : A2006-064 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article DOI : 10.1080/13658810500399589 En ligne : https://doi.org/10.1080/13658810500399589 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27791 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

A new approach to the nearest-neighbour method to discover cluster features in overlaid spatial point processes / Tao Pei in International journal of geographical information science IJGIS, vol 20 n° 2 (february 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 2 (february 2006) . - pp 153 - 168 Titre : A new approach to the nearest-neighbour method to discover cluster features in overlaid spatial point processes Type de document : Article/Communication Auteurs : Tao Pei, Auteur ; A - Xing Zhu, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 153 - 168 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] Chine [Termes IGN] classification barycentrique [Termes IGN] distribution de Poisson [Termes IGN] filtrage du bruit [Termes IGN] groupe [Termes IGN] regroupement de données [Termes IGN] segmentation d'image [Termes IGN] séisme [Termes IGN] variation de densité Résumé : (Auteur) When two spatial point processes are overlaid, the one with the higher rate is shown as clustered points, and the other one with the lower rate is often perceived to be background. Usually, we consider the clustered points as feature and the background as noise. Revealing these point clusters allows us to further examine and understand the spatial point process. Two important aspects in discerning spatial cluster features from a set of points are the removal of noise and the determination of the number of spatial clusters. Until now, few methods were able to deal with these two aspects at the same time in an automated way. In this study, we combine the nearest-neighbour (NN) method and the concept of density-connected to address these two aspects. First, the removal of noise can be achieved using the NN method; then, the number of clusters can be determined by finding the density-connected clusters. The complexity for finding density connected clusters is reduced in our algorithm. Since the number of clusters depends on the value of k (the kth nearest neighbour), we introduce the concept of lifetime for the number of clusters in order to measure how stable the segmentation results (or number of clusters) are. The number of clusters with the longest lifetime is considered to be the final number of clusters. Finally, a seismic example of the west part of China is used as a case study to examine the validity of our method. In this seismic case study, we discovered three seismic clusters: one as the foreshocks of the Songpan quake (M=7.2), and the other two as aftershocks related to the Kangding-Jiulong (M=6.2) quake and Daguan quake (M= 7. 1), respectively. Through this case study, we conclude that the approach we proposed is effective in removing noise and determining the number of feature clusters. Numéro de notice : A2006-065 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810500399654 En ligne : https://doi.org/10.1080/13658810500399654 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27792 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

The accuracy of grid digital elevation models linearly constructed from scattered sample data / F. Aguilar in International journal of geographical information science IJGIS, vol 20 n° 2 (february 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 2 (february 2006) . - pp 169 - 192 Titre : The accuracy of grid digital elevation models linearly constructed from scattered sample data Type de document : Article/Communication Auteurs : F. Aguilar, Auteur ; M. Aguilar, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 169 - 192 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] couple stéréoscopique [Termes IGN] écart type [Termes IGN] échantillonnage de données [Termes IGN] erreur d'échantillon [Termes IGN] erreur moyenne quadratique [Termes IGN] image aérienne [Termes IGN] interpolation linéaire [Termes IGN] maille carrée [Termes IGN] modèle numérique de surface [Termes IGN] modélisation 3D [Termes IGN] pente [Termes IGN] propagation d'erreur [Termes IGN] rugosité du sol [Termes IGN] système d'information géographique Résumé : (Auteur) In this paper, a theoretical-empirical model is developed for modelling the accuracy of a grid digital elevation model (DEM) linearly constructed from scattered sample data. The theoretical component integrates sample data accuracy in the model by means of the error-propagation theory. The empirical component seeks to model what is known as information loss, i.e. the sum of the error due purely to sampling the continuous terrain surface with a finite grid interval and the interpolation error. For this purpose, randomly spaced data points, supposed to be free of error, were converted into regularly gridded data points using triangulation with linear interpolation. Original sample data were collected with a 2 x 2 m sampling interval from eight different morphologies, from flat terrain to highly rugged terrain, applying digital photogrammetric methods to large-scale aerial stereo imagery (1 :5000). The DEM root mean square error was calculated by the true validation method over several sets of check points, obtaining the different sampling densities tested in this work. Several empirical models are calibrated and validated with the experimental data set by modelling the DEM accuracy by combining two variables such as sampling density and a descriptive attribute of terrain morphology. These empirical models presented a morphology based on the product of two potential functions, one related to the terrain roughness and another related to the sampling density. The terrain descriptors tested were average terrain slope, standard deviation of terrain slope, standard deviation of unitary vectors perpendicular to the topographic surface (SDUV), standard deviation of the difference in height between adjacent samples in the grid DEM (SDHD), and roughness estimation by first-, second-, or third-degree surface fitting error. The values obtained for those terrain descriptors were reasonably independent from the number and spatial distribution of the sample data. The models based on descriptors SDHD, SDUV, and standard deviation of slope provided a good fitting to the data observed (R 2> 0.94) in the calibration phase, model SDHD being the one that yielded the best results in validation. Therefore, it would be possible to establish a priori the optimum grid size required to generate or store a DEM of a particular accuracy, with the saving in computing time and file size that this would mean for the digital flow of the mapping information in GIS. Numéro de notice : A2006-066 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810500399670 En ligne : https://doi.org/10.1080/13658810500399670 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27793 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

An efficient method for identifying and filling surface depressions in digital elevation models for hydrologic analysis and modelling / L. Wang in International journal of geographical information science IJGIS, vol 20 n° 2 (february 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 2 (february 2006) . - pp 193 - 213 Titre : An efficient method for identifying and filling surface depressions in digital elevation models for hydrologic analysis and modelling Type de document : Article/Communication Auteurs : L. Wang, Auteur ; H. Liu, Auteur Année de publication : 2006 Article en page(s) : pp 193 - 213 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG [Termes IGN] bassin hydrographique [Termes IGN] C++ [Termes IGN] données lidar [Termes IGN] hydrographie de surface [Termes IGN] image à haute résolution [Termes IGN] modèle numérique de surface [Termes IGN] ruissellement [Termes IGN] système d'information géographique [Termes IGN] temps de réponse Résumé : (Auteur) Identification and removal of surface depressions is a critical step for automated modelling of surface rainfall runoff based on Digital Elevation Models (DEMs). At prescrit, nearly all GIS and hydrologic software packages employ Jensen and Domingue's method for preparing depressionless DEMs for hydrologic analysis. This conventional method is computationally intensive and time-consuming. With the growing availability of high-resolution DEMs produced by airborne LIDAR and InSAR techniques, GIS-based hydrologic applications often need to handle larger geographic areas at finer resolutions. In the face of high-resolution DEMs, the conventional method becomes inadequate and deficient. In this paper, we present a new method for efficiently identifying and filling surface depressions in DEMs. This method can simultaneously determine flow paths and spatial partition of watersheds with one pass of processing. A novel concept of spill elevation and the least-cost search for optimal flow paths are the two cornerstones of our method. The time complexity of our method is in O(Nlog N). It has been implemented using C+ + programming language and successfully applied to USGS DEMs and LIDAR DEMs of various sizes. Experiments show that our method outperforms the conventional method by a factor of over 30, in terms of running time. Numéro de notice : A2006-067 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810500433453 En ligne : https://doi.org/10.1080/13658810500433453 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27794 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06022	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Application of GIS to investigate the use of space in coral reef fish: a comparison of territorial behaviour in two Red Sea butterflyfishes / D. Righton in International journal of geographical information science IJGIS, vol 20 n° 2 (february 2006)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 20 n° 2 (february 2006) . - pp 215 - 232 Titre : Application of GIS to investigate the use of space in coral reef fish: a comparison of territorial behaviour in two Red Sea butterflyfishes Type de document : Article/Communication Auteurs : D. Righton, Auteur ; C. Mills, Auteur Année de publication : 2006 Article en page(s) : pp 215 - 232 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG [Termes IGN] Aqaba, golfe d' [Termes IGN] comportement [Termes IGN] faune aquatique [Termes IGN] poisson (faune aquatique) [Termes IGN] récif corallien [Termes IGN] système d'information géographique [Termes IGN] territoire Résumé : (Auteur) The space use of two coral-feeding Red Sea butterflyfish species (Chaetodon austriacus and C trifascialis) was studied at three sites in the Gulf of Aqaba to determine the extent of intraspecific territoriality. Individuals or pairs were observed in shallow water ( Numéro de notice : A2006-068 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810500399159 En ligne : https://doi.org/10.1080/13658810500399159 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27795 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-06021	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-06022	RAB	Revue	Centre de documentation	En réserve L003	Disponible