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Image Processing
MDA's EarthSat GeoVue and EarthSat MineralVue image enhancement techniques display geologic structures, through linear band combinations, to analytic techniques that enhance surface reflectance differences of vegetation and lithology to aid mineral exploration.
GeoVue and MineralVue
The GeoVue enhancement is a six band interactive process that maximizes the differences in reflected surface information and increases soil and lithologic detail. The resulting image products have a high correspondence to geologic units on geologic maps, but with more detail. In some areas, alteration zones are readily apparent.
TM GeoVue
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TM GeoVue
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Ratioing, when done correctly, is a tested, reliable, repeatable and simple method for locating and classifying hydrothermally altered lithologies. In frontier areas, ratio image composites are noisy and have relatively little spatial information. GeoVue, on the other hand, maximizes qualitative differentiation of surface features and suppresses vegetation signatures. By combining the hue information of ratio composites with the sharpness and clarity of GeoVue processing, MineralVue provides an image that is well suited for both quantitative lithologic mapping and detailed structural interpretation of faults and fractures.
MineralVue enables an interpreter to estimate the relative mineral content of exposed lithologies in terms of clay/hydroxyl/bound-water, ferric and/or ferrous iron mineral groups, and vegetation density. Alteration zones can be classified and compared in terms of relative surface mineral content. MineralVue is also used to detect the alteration of sedimentary formations to clay minerals caused by hydrocarbon microseepage.
Example
MineralVue I was designed for hydrothermal alteration mapping. The accompanying MineralVue image is of a sparsely vegetated area in the western Andean Cordillera.
The red color indicates high relative ferric iron content (goethite/-jarosite/limonite).
Green areas indicate high concentrations of hydroxyl- and/or bound-water-bearing mineral groups relative to vegetation and iron oxides. Potential mineral groups include: clay minerals (kaolinite, illite, montmorillonite, alunite and sericite-bearing mica) and sulfates. Secondary possibilities include carbonates and aluminum-bearing pyroxenes.
Yellow and orange hues indicate the presence of both iron oxides and clay-bearing mineral groups. The brighter the yellow the more intense the supergene alteration.
The approximate relative concentrations of iron (red) and clay (green) can be inferred from the color: yellow - equal amounts of iron and clay, reddish orange - more iron, yellowish green - more clay.
