A 2D FFT filtering program for image processing with examples
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Geology topics
Publications and source records attributed to Kenneth Watson.
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The Nimbus III and IV satellites provide reflectance and emittance data from the earth's surface at 8-km resolution. These data have been used to derive a physical property of geologic materials termed '"thermal inertia" which appears to have great promise for discriminating surficial units. A thermal inertia map of part of Oman was produced from the Nimbus satellite measurements. Correlation of this map with a reconnaissance geologic map showed gross agreement with the major units but also suggested the need for some modifications of the reconnaissance map. Some of the anomalies were verified by comparison with a later, more detailed map; others remain unexplained and may indicate previously undiscriminated geologic units.
Thermal-infrared images obtained on flights over the Tishomingo anticline and South Flank areas near Mill Creek in the Arbuckle Mountains, Oklahoma, were used to study the possibility of identifying some common rock types from their diagnostic reflection and emission characteristics, and to evaluate the usefulness of infrared images in structural geologic investigations. The areas flown are underlain by folded and faulted Paleozoic dolomite, limestone, sandstone, shale, and Precambrian granite. Images were obtained at 6:00 a.m., 11:00 a.m., and 2:00 p.m. The predawn (6:00 a.m.) image is the most useful in distinguishing rock types. Of particular interest is a thermal contrast of dolomite (warm) and limestone (cool), sufficient to distinguish those rock types and to reveal facies changes between them. Theoretical considerations indicate that this thermal contrast arises from a combination of albedo and thermal-inertia characteristics distinctive of dolomites and limestones in many areas. The daytime images display much stratigraphic and structural detail. Small-scale bedding detail is enhanced in the morning images of low-relief areas, and contrasts of alternating formations that form hogbacks and valleys are enhanced in the afternoon images of higher relief areas. The difference in features displayed in morning and afternoon images appears to be a function of the insolation on sunward and shadowed slopes of differing scale. Fault or fracture zones are best displayed in the predawn image; they appear cooler than surrounding ground, because of greater water content and concomitant evaporation. The abundance and throughgoing nature of lineaments (which coincide for the most part with joint systems) are more obvious in the infrared images than in aerial photographs. Lineaments striking northwest are preferentially enhanced in the morning images, and lineaments striking northeast are preferentially shown in the afternoon images. This enhancement cannot be ascribed to the effects of topography, insolation, or wind; it may relate to a combination of ground-water and vegetation effects.
Field Sites have been selected for controlled experiments to analyze physical and chemical parameters affecting the response of electromagnetic radiation to geological materials. Considerations in the selection of the sites are the availability of good exposures of nearly monomineralic rocks, level of geologic understanding, and ease of access. Seven sites, where work is underway or planned, contain extensive outcrops of the following rocks: stanstone, limestone, dolomite, and gypsum. Field measurement of quartz have been conducted at four sites.
As part of the U.S. Geological Survey's Remote Sensor Application Studies program, infrared images and several kinds of photographs were obtained on reconnaissance flights over two areas in the Arbuckle Mountains near Mill Creek, Oklahoma. These data were used in a preliminary investigation (1) to determine the diagnostic reflection and emission characteristics of various rock types, and (2) io evaluate the perturbing influence of atmospheric conditions, surface coatings, rock texture, and topography on the observed reflected and emitted energy in the thermal infrared (8-14μ) part of the spectrum
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