Centre de documentation
scientifique

Dépouillements

Geometric variability of raster cell class assignment / A.M. Shortridge in International journal of geographical information science IJGIS, vol 18 n° 6 (october 2004)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 6 (october 2004) . - pp 539 - 558 Titre : Geometric variability of raster cell class assignment Type de document : Article/Communication Auteurs : A.M. Shortridge, Auteur Année de publication : 2004 Article en page(s) : pp 539 - 558 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] classification [Termes IGN] données maillées [Termes IGN] données vectorielles [Termes IGN] grille [Termes IGN] limite de résolution géométrique [Termes IGN] maille carrée [Termes IGN] pixel [Termes IGN] polygone [Termes IGN] rastérisation [Termes IGN] simulation Résumé : (Auteur) Applications like land-cover mapping frequently require the transformation of vector polygons to raster grids, such that each cell in the output raster is assigned a single class. Cell value assignment is a direct function of the geometric relationship between the vector polygons and the origin, orientation and spatial resolution of the raster structure, acting in conjunction with the value assignment rule employed by the algorithm. Results of an alternative approach to characterizing origin assignment variability are reported. A simulation approach is employed to perturb the origin of the grid lattice by amounts smaller than the grid spacing. The distribution of results across all output raster realizations indicates the rasterization variability for a particular input vector map at a particular cell size. Results for a representative vector land-cover dataset are presented, indicating that substantial variability is possible. The paper concludes with a discussion of theoretical and practical implications for the identification of appropriate cell resolutions, as well as for identifying particular input shapes and polygon configurations that may be especially sensitive to rasterization error. Numéro de notice : A2004-349 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810410001702012 En ligne : https://doi.org/10.1080/13658810410001702012 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26876 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-04061	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-04062	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Accuracy of the coefficient expansion of the transverse Mercator projection / E. Enriquez in International journal of geographical information science IJGIS, vol 18 n° 6 (october 2004)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 6 (october 2004) . - pp 559 - 576 Titre : Accuracy of the coefficient expansion of the transverse Mercator projection Type de document : Article/Communication Auteurs : E. Enriquez, Auteur Année de publication : 2004 Article en page(s) : pp 559 - 576 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie numérique [Termes IGN] coordonnées géodésiques [Termes IGN] ellipsoïde (géodésie) [Termes IGN] latitude [Termes IGN] précision géométrique (imagerie) [Termes IGN] projection de Gauss [Termes IGN] projection Universal Transverse Mercator [Termes IGN] système d'information géographique Résumé : (Auteur) Problems of precision and accuracy in geographical information systems have often been undervalued. However, these are important issues when trying to avoid inaccurate computations that could distort the final result. A method is described for the Transverse Mercator Projection of the ellipsoid to calculate the necessary number of terms of their series development so that desired accuracy can be achieved. The first part describes one algorithm used to obtain the full development of the formulas by means of a symbolic calculus program. The second part studies the influence of each term in the final result in order to know which terms can be neglected while achieving the desired precision. Finally, the results are applied to a rectangle of 30° width and latitude varying from 30° to 50°. Numéro de notice : A2004-350 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810410001701996 En ligne : https://doi.org/10.1080/13658810410001701996 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26877 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-04061	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-04062	RAB	Revue	Centre de documentation	En réserve L003	Disponible

The choice of window size in approximating topographic surfaces from digital elevation models / M. Albani in International journal of geographical information science IJGIS, vol 18 n° 6 (october 2004)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 6 (october 2004) . - pp 577 - 593 Titre : The choice of window size in approximating topographic surfaces from digital elevation models Type de document : Article/Communication Auteurs : M. Albani, Auteur ; Brian Klinkenberg, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 577 - 593 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] autocorrélation spatiale [Termes IGN] Colombie-Britannique (Canada) [Termes IGN] erreur de mesure [Termes IGN] méthode des moindres carrés [Termes IGN] modèle numérique de surface [Termes IGN] profil topographique [Termes IGN] propagation d'erreur [Termes IGN] topographie locale Résumé : (Auteur) Quantitative surface analysis through quadratic modelling of Digital Elevation Models (DEMs) is a promising tool for automatically describing the physical environment in ecological studies of terrestrial landscapes. Fundamental topographic variables such as slope, aspect, plan and profile curvature can be simply calculated from the parameters of a conic equation fitted to a DEM window through the least-squares method. The scale of the analysis, defined by the size of the DEM window used to fit the conic equation, affects both the estimated value of the topographic variables and the propagation of elevation errors to derived topographic variables. The least-squares method is amenable to the analytical treatment of the propagation of elevation errors to the derived topographical variables. A general analytical model of error propagation is presented that accounts for the effects of window size and of spatial autocorrelation in elevation errors. The method is based on the Taylor approximation of the least-square fitting equation and allows for the presence of stationary autocorrelation in the elevation errors. In numerical simulations with DEMs from British Columbia, Canada, it is shown that increasing the size of evaluation windows effectively reduces the propagation of elevation errors to the derived topographic variables. However, this was obtained at the expense of topographic detail. A methodology is proposed to evaluate quantitatively the loss of topographic detail through a X2-test of the corrected residuals in the immediate neighbourhood of the evaluation point. This methodology, in combination with the analytical model of error propagation, can be used to select the scale or range of scales at which to calculate topographic variables from a DEM. Numéro de notice : A2004-351 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810410001701987 En ligne : https://doi.org/10.1080/13658810410001701987 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26878 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-04061	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-04062	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Effect of support size on the accuracy of a distributed rockfall model / L.K.A. Dorren in International journal of geographical information science IJGIS, vol 18 n° 6 (october 2004)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 6 (october 2004) . - pp 595 - 609 Titre : Effect of support size on the accuracy of a distributed rockfall model Type de document : Article/Communication Auteurs : L.K.A. Dorren, Auteur ; Gerard B.M. Heuvelink, Auteur Année de publication : 2004 Article en page(s) : pp 595 - 609 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] agrégation spatiale [Termes IGN] analyse comparative [Termes IGN] éboulement [Termes IGN] erreur moyenne quadratique [Termes IGN] modèle de simulation [Termes IGN] modèle numérique de surface [Termes IGN] prévention des risques [Termes IGN] système d'information géographique Résumé : (Auteur) It is investigated whether a GIS-based distributed model developed for rockfall assessment at slope scale, which uses data with a support of 2.5 x 2.5 m, could be used for rockfall assessment at the regional scale, using input data with a support of 25 x 25 m and of poorer quality. It was anticipated that in the latter case the model error would increase. Three types of simulations were applied to the same model and the outcomes were validated with field data. The first simulation used input data with a support of 2.5 x 2.5 m and aggregated the output to a support of 25 x 25 m. The second simulation used the same input data as in the first simulation, but these data were aggregated to a support of 25 x 25 m before running the model. The third simulation used input data of poorer quality obtained at a support of 25 x 25 m. The results show that simulating the maximum extent of rockfall runout zones with a distributed model using data with a support of 25 x 25 m is realistic and feasible. This is also true for data with poorer quality as the third simulation resulted in a slightly larger mean-squared error than the first simulation. Surprisingly, it also gave a smaller error than the second simulation. We investigated the cause of the large error produced by the second simulation and concluded that this was mainly caused by the combination of a high-quality digital elevation model and the loss of spatial structure in the input data due to spatial aggregation. Numéro de notice : A2004-352 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810410001703804 En ligne : https://doi.org/10.1080/1365881041000170380403804 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26879 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-04061	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-04062	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Spatial variability in classification accuracy of agricultural crops in the Dutch national land-cover database / A.J.W. Van Oort in International journal of geographical information science IJGIS, vol 18 n° 6 (october 2004)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 6 (october 2004) . - pp 611 - 626 Titre : Spatial variability in classification accuracy of agricultural crops in the Dutch national land-cover database Type de document : Article/Communication Auteurs : A.J.W. Van Oort, Auteur ; Arnold K. Bregt, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 611 - 626 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie numérique [Termes IGN] base de données d'occupation du sol [Termes IGN] base de données localisées [Termes IGN] classe d'objets [Termes IGN] cultures [Termes IGN] données maillées [Termes IGN] occupation du sol [Termes IGN] Pays-Bas [Termes IGN] paysage [Termes IGN] pixel [Termes IGN] précision de la classification Résumé : (Auteur) Variability in per cell classification accuracy is predominantly modelled with landcover class as the explanatory variable, i.e. with users' accuracies from the error matrix. Logistic regression models were developed to include other explanatory variables: heterogeneity in the 3 x 3 window around a cell, the size of the patch and the complexity of the landscape in which a cell is located. It was found that per cell, the probability of correct classification was significantly (a = 0.05) higher for cells with a less heterogeneous neighbourhood, for cells part of larger patches and for cells in regions with a less heterogeneous landscape. To validate the models, a leave-one-out procedure was applied in which the absolute difference between the actual and the model-estimated number of cells correctly classified was summarized over 55 regions in the Netherlands. The sum of differences reduced from 60.9 to 48.1 after adding the variables 'patch size' and 'landscape dominance' to the land-cover class model. Spatial variability thus modelled therefore led to a substantial improvement in the estimation of the per cell classification accuracy. Numéro de notice : A2004-353 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810410001701969 En ligne : https://doi.org/10.1080/13658810410001701969 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26880 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-04061	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-04062	RAB	Revue	Centre de documentation	En réserve L003	Disponible