A CDE Definition
earth satellite thematic sensing
(Data West Research Agency definition: see GIS glossary.) Landsat satellites have a Thematic-Mapper (tm) sensor that produces images in many spectral regions, e.g., in the visible range, in the near-infrared, in the mid-infrared, and in the thermal infrared. The visible and near-infrared regions provide information on water turbidity, bathymetry, currents, and sediment plumes. (Water containing large quantities of suspended sediment has a higher reflectance than clear water and can be easily separated using satellite data). The near-infrared band is used for vegetation mapping since it distinguishes features by variations in plant cell structure. Mid-infrared spectral regions reveal plant water content and help delineate vegetation type. Two mid-infrared bands are used for geological studies and one for collecting imagery at night and identifying hot objects, such as forest fires, lava flows, emissions from smoke stacks, new construction, and soil use.
The GIS terms under the entries GIS glossary: a-g and GIS glossary: h-t are condensed and reproduced with permission from "A Practitioner's Guide to GIS Terminology" by Stearns J. Wood. Compiled over 30 years and first published in 1984, the book contains more than 10,000 terms embracing all aspects of geoprocessing and geoanalysis, spatial and network analysis, resource management, facilities management, automated mapping, computer-aided design and drafting, database management systems, open systems connectivity and geographic information system computer technology. Selected terms from geography, cartography, computer science, urban and regional information systems, remote sensing and GPS are also included. See GIS glossary: a-g and GIS glossary: h-t.
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