GEOSCAN, résultats de la recherche


TitreQuantitative mapping of eskers using DEM and multispectral data
AuteurBroscoe, D; Russell, H A J
SourceGeological Society of America, Abstracts With Programs vol. 46, no. 6, 2014 p. 522
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140200
ÉditeurGeological Society of America
RéunionGeological Society of America, Annual Meeting 2014; Vancouver; CA; Octobre 19-22, 2014
Documentpublication en série
Mediapapier; numérique
Sujetseskers; cartographie par ordinateur; techniques de cartographie; télédétection; topographie; topographie glaciaire; satellite LANDSAT; images du satellite LANDSAT; géologie des dépôts meubles/géomorphologie
ProgrammeAquifer Assessment & support to mapping, Géoscience des eaux souterraines
Résumé(disponible en anglais seulement)
Eskers have commonly been mapped and symbolized manually from aerial photographic interpretation as either lines (ridges) and polygons (sand and gravel). To-date no method has been deployed that could automatically extract esker extents and quantify the esker volume. A methodology is presented for the quantification of eskers that uses Canadian Digital Elevation Data (CDED), spectral remotely sensed imagery (e.g. LandSat, Spot), and legacy esker line work from Geological Survey of Canada publications. Using ArcGIS and an esker detection module (EDM) coded in Python, the CDED data are smoothed using user defined filter windows. A difference surface is produced that emphasizes ridge areas and is used to create polygons. The legacy esker line work is used as a training dataset to extract ridge areas within a user defined buffer. EDM results have been tested against the input training data and a local data set generated manually from aerial photographic interpretation. Depending upon terrain characteristics the success of the data extraction ranges from 65 to 81 % against the esker line work and 35 to 72 % against the more limited aerial photographic interpretation. The variable success reflects esker size related to both relief and width in the CDED data. Ongoing development of this methodology focuses on enhanced delineation of low-relief areas of the esker not captured by the DEM analysis through incorporation of spectral imagery. A multiclass (80-90) iso-cluster unsupervised classification of SPOT MSS data was completed to characterize the landscape. The isocluster classification is then overlain on the esker polygons. The most dominant classes in terms of area are identified and the user can specify the number of classes to be chosen. The originally topographically defined polygons are then merged with the selected intersecting spectral classification.
Résumé(Résumé en langage clair et simple, non publié)
Cette publication documente une approche de cartographie automatisée à partir d'un jeu de données de formation pour obtenir des données quantitative sur les eskers.