Cartography and Geographic Information Science / Cartography and geographic information society . vol 31 n° 2Paru le : 01/04/2004 ISBN/ISSN/EAN : 1523-0406 |
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Ajouter le résultat dans votre panierHillshading of terrain using layer tints with aspect-variant luminosity / Patrick Kennelly in Cartography and Geographic Information Science, vol 31 n° 2 (April 2004)
[article]
Titre : Hillshading of terrain using layer tints with aspect-variant luminosity Type de document : Article/Communication Auteurs : Patrick Kennelly, Auteur ; A.J. Kimerling, Auteur Année de publication : 2004 Article en page(s) : pp 67 - 77 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie numérique
[Termes IGN] éclairement lumineux
[Termes IGN] estompage
[Termes IGN] luminance lumineuse
[Termes IGN] transformation intensité-teinte-saturationRésumé : (Auteur) Hillshading provides a rendering of topographic surfaces by assigning brightness to surface elements based on the orientation of these elements and a selected direction of illumination. Users easily visualize many topographic features, but some areas lack detail, as one shade of gray does not define a unique surface orientation. We clarify some of this ambiguity by varying the color of layer tints with aspect direction. We use the CIELAB [commission internationale de l'éclairage] color model to quantify color specifications and map variations in luminosity onto slices of the Hue-Saturation-Value (HSV) color model. Traditionally, cartographers assign an aspect-invariant color (or colors) based on H and S and vary V with the hillshading values. In our research, we assign aspect-variant H and V values in close proximity in HSV color space. We use values of luminosity and saturation from the CIELAB and HSV color models to select colors that are least saturated, most saturated, least luminous, and most luminous to represent the northwest, southeast, southwest, and northeast directions, respectively. We then vary V in the traditional manner with hillshading from the northwest. Topographic details not apparent in the original hillshaded mas are highlighted with this technique. Numéro de notice : A2004-340 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1559/1523040041649416 En ligne : https://doi.org/10.1559/1523040041649416 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26867
in Cartography and Geographic Information Science > vol 31 n° 2 (April 2004) . - pp 67 - 77[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 032-04021 RAB Revue Centre de documentation En réserve L003 Disponible Toward a differential calculus for temporal map analysis / Denis J. Dean in Cartography and Geographic Information Science, vol 31 n° 2 (April 2004)
[article]
Titre : Toward a differential calculus for temporal map analysis Type de document : Article/Communication Auteurs : Denis J. Dean, Auteur Année de publication : 2004 Article en page(s) : pp 89 - 101 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] analyse diachronique
[Termes IGN] analyse spatio-temporelle
[Termes IGN] calcul différentiel
[Termes IGN] détection de changement
[Termes IGN] interpolationRésumé : (Auteur) Investigators in many fields are analyzing temporal change in spatial data. Such analyses are typically conducted by comparing the value of some metric (e.g., area, contagion, or diversity indices) measured at time T1, with the value of the same metric measured at time T2, These comparisons typically include the use of simple interpolation models to estimate the value of the metric of interest at points in time between observations, followed by applications of differential calculus to investigate the rates at which the metric is changing. Unfortunately, these techniques treat the values of the metrics being analyzed as if they were observed values, when in fact the metrics are derived from more fundamental spatial data. The consequence of treating metrics as observed values is a significant reduction in the degrees of freedom in spatial change over time. This results in an oversimplified view of spatio-temporal change. A more accurate view can be produced by (1) applying temporal interpolation models to observed spatial data rather than derived spatial metrics; (2) expanding the metric of interest's computational equation by replacing the terms relating to the observed spatial data with their temporal interpolation equations; and (3) differentiating the expanded computational equation. This alternative, three-step spatio-temporal analysis technique will be described and justified. The alternative technique will be compared to the conventional approach using common metrics and a sample data set. Numéro de notice : A2004-341 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1559/1523040041649380 En ligne : https://doi.org/10.1559/1523040041649380 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26868
in Cartography and Geographic Information Science > vol 31 n° 2 (April 2004) . - pp 89 - 101[article]Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 032-04021 RAB Revue Centre de documentation En réserve L003 Disponible