Contributions to Geology 12.2

Introduction to NASA earth resources remote-sensing programs

R. W. MARRS Department of Geology, University of Wyoming, Laramie, Wy. 82071

Pages
1-6

Keywords
NASA, ERTS, remote sensing, Wyoming, EROS, scanner, Skylab, satellite

Abstract
Useful remote sensor data of Wyoming have been obtained through three National Aeronautics and Space Administration earth resources programs:

1) the Earth Resources Technology Satellite (ERTS) program.
2) the Earth Resources Experiment Package (EREP) used on Skylab, and
3) the Earth Resources Aircraft Program (ERAP).

Index maps prepared by the University of Wyoming, Remote Sensing Laboratory show the extent of coverage from each of these three sensors. The data largely comprise photographs, magnetic tapes, and scanner images, all of which are available from the EROS data center. Other special products can be obtained from other government agencies or industrial concerns.

Introduction to Earth Resources Remote-Sensing Programs

R. W. MARRS

Pages
1-6

Keywords
Introduction to Earth Resources Remote-Sensing Programs

Abstract
Useful remote sensor data of Wyoming have been obtained through three National Aeronautics and Space Administration earth resources programs:

Digital image enhancement techniques used in some ERTS application problems

ALEXANDER F. H. GOETZ and FRED C. BILLINGSLEY Jet Propulsion Laboratory, California Instilute of Technology, Pasadena, California

Pages
7-22

Keywords
ERTS, enhancement, contrast, spatial frequency

Abstract
Enhancement and classification are not competing methods for machine image analysis. In fact enhanced images can be used alone or as inputs to classification routines. However, in some problems the spatial relationships are equal in importance to the classification results and enhancements can be designed to provide both types of information in one image.

Enhancements discussed include contrast stretching, multiratio color displays, Fourier plane operations to remove striping and boosting MTF response to enhance high spatial frequency content. The use of each technique in a specific application in the fields of geology, geomorphology and oceanography is demonstrated.

Digital Image Enhancement Techniques Used in Some ERTS Application Problems

ALEXANDER F. H. GOETZ and FRED C. BILLINGSLEY

Pages
7-21

Keywords
Digital Image Enhancement Techniques Used in Some ERTS Application Problems

Abstract
Enhancement and classification are not competing methods for machine image analysis. In fact enhanced images can be used alone or as inputs to classification routines. However, in some problems the spatial relationships are equal in importance to the classification results and
enhancements can be designed to provide both types of information in one image.</p>

Enhancements discussed include contrast stretching, multiratio color displays, Fourier plane operations to remove striping and boosting MTF response to enhance high spatial frequency content. The use of each technique in a specific application in the fields of geology, geomorphology and oceanography is demonstrated.</p>

Interpretative techniques in remote sensing

R. W. MARRS Department of Geology, University of Wyoming, Laramie, Wy. 82071

Pages
23-32

Keywords
stereoscopic, remote sensing, interpretation, ratioing, cluster analysis, enhancement

Abstract
Increasing availability of remote-sensor data and improving interpretative techniques have resulted in recognition of remote sensing as a valuable tool for the geoscientist. Much can be gained from some of these data by applying traditional photointerpretive techniques, but still more can be gained if specialized interpretive techniques are selectively employed. Proper use of new interpretive techniques requires that the user have a basic understanding of the dataÑhow it is obtained and what it represents. The user must also keep in mind the limitations of the data, such as its spectral, spatial, and brightness resolution.

With these considerations in mind, the user is ready to select the type of remote sensor data that will best apply to his problem and then tailor the processing and analysis of these data to obtain the maximum amount of information with the least expense.

The geoscientist may employ various forms of image enhancement or he may choose to use the computer in helping him make his discriminations and classifications. Some enhancement techniques are employed with visual image analysis, such as color-additive and color-subtractive viewing, stereoscopic and pseudo-stereoscopic photo interpretation. A few procedures are ordinarily accomplished through computer analysis (brightness ratioing, atmospheric correction), but others are effective with either imagery or numerical data. This latter group includes contrast stretching, density slicing, cluster analysis, pattern recognition, frequency analysis, and edge enhancement. Most procedures can be done in several ways, with the accuracy of the results and the efficiency of the operation largely dependent on the equipment used. Thus, the economics of the situation are the final consideration in the implementation of most interpretive techniques.

Geologic interpretations of ERTS-1 imagery, Bighorn Mountains

RICHARD A. HOPPIN Department of Geology, University of Iowa, Iowa Citv, Iowa, 52242 RONALD D. MANLEY Chevron Corporation, Lafayette, Louisiana
DANIEL M. TAPPMEYER and NELS E. VOLDSETH Texaco, Incorporated Midland, Texas

Pages
33-42

Keywords
fracture, ERTS, Bighorn Mountains, remote sensing, uplift, linear

Abstract
ERTS-1 imagery provides a superb regional view which confirms the complex nature of the Bighorn uplift. Many structures can be correlated with known features. Others can be extended beyond their presently mapped limits and some separated features, such as the Badwater-Big Trails faults, can be connected. Linears are mainly confined to the uplift. Most linears are topographically expressed, with the rest being marked by tonal contrasts. Many linears can be related to faults or fracture zones, but others occur along drainages with no bedrock exposed. Linear plots of ERTS imagery, aerial photography, and fracture diagrams all show the dominant trends to be N. to N.20 E NE, and E-W. The strong northwest trend of anticlines and monoclines and of ground-measured fractures is subdued on the ERTS imagery owing to the southeast sun azimuth.

Mapping of lithologies is less satisfactory and can be done only in a general way. Remote sensing unit contacts seldom correspond to stratigraphic contacts. Nevertheless the patterns are helpful in outlining many folds.

Multilevel sensing as an aid in mineral exploration - Iron Formation example

ROBERT S. HOUSTON Department of Geology, University of Wyoming, Laramie, Wy. 82071

Pages
43-60

Keywords
mineral, Iron Formation, ERTS, Skylab, Wyoming, mapping

Abstract
Multilevel sensing takes advantage of the varying detail available from images acquired with platforms flying at different attitudes (ERTS, Skylab, aircraft). Space imagery can be used to target areas of interest. Aircraft data can then be used to study these areas in greater detail, thus saving much of the time and expense involved in complete analysis by standard photointerpretive procedures.

The multilevel approach was used in locating and mapping areas of Precambrian greenstone in Central Wyoming. The ERTS imagery and Skylab photography was successfully used to map the large areas of greenstone outcrop. The available aerial photography was employed in mapping particular lithologies (such as iron formation) within the greenstone belts.

Comparison of ERTS, Skylab 190A and 190B sensors, and aircraft photographs for lineation mapping

B. J. TOMES, R. W. MARRS, RONALD B. PARKER, and R. S. HOUSTON Department of Geology, University of Wyoming, Laramie, Wy. 82071

Pages
61-68

Keywords
ERTS, Skylab, lineation, comparison, resolution, fault

Abstract
The spacecraft image has a major advantage in lineation studies because of the synoptic view, but low resolution is a major disadvantage. Two major factors affect lineation mapping, spatial resolution and illumination direction. A portion of the Wind River Mountains in central Wyoming has been studied using ERTS images, Skylab 190A and 190B photographs, aerial photographs, and field techniques.

Lineations are emphasized as a function of the sun azimuth and sun elevation. In a comparison study, ERTS images show a bias towards northeast-striking linear features perpendicular to the sun azimuth of 146 degrees, whereas Skylab photography of the same area indicates a dominant northwest trend perpendicular to the 199 degree sun azimuth. Resolution comparisons show that Skylab photography allows detection of approximately twice as many linear elements than does the ERTS imagery. Resolution on aerial photography is several times better than ERTS or Skylab, however, regional trends were lost for the detail. A comparison of known faults and photolinear elements shows good correspondence.

ERTS MSS imagery applied to mapping and economic evaluation of sand dunes in Wyoming

KENNETH E. KOLM Department of Geology, University of Wyoming, Laramie, Wy. 82071

Pages
69-76

Keywords
dunes, ERTS, Wyoming, mapping, mining, wind patterns

Abstract
Active and stabilized dune fields of regional extent were mapped using ERTS imagery. Previously mapped dune fields (Ahlbrandt, 1973b; Houston, 1973; Love, J. D., Weitz, J. L., and Hose, R. K., 1955, Roehler 1969) were confirmed by the ERTS image study, and some new dune fields were discovered. Additional confirmation was provided by field work and high-altitude aerial photographs which were available for some areas.

Results indicate that color composite ERTS images are most helpful in locating active dune fields. This is attributed to subtle color differentiation between active dunes, clouds, sandy alluvium, pediments, alkali flats, snow fields, and light-colored rock formations. The color composite images were also employed in mapping stabilized dune fields which usually exhibited a brown-green coloration characteristic of sparse and relatively dormant vegetation. The contrasts between both stable and active dunes and the surroundings were most apparent on the image transparencies, because the transparencies have higher resolution and greater flexibility in the intensity of illumination than do the prints. Color prints were most convenient for field use. Another general advantage of ERTS imagery is the display of regional linear patterns and topographic features. Cross-cut relations between dune fields and surrounding rock formations were also recognized.

The disadvantages of ERTS imagery are: 1) the imagery is of a small scale, and small dune fields were sometimes missed; and 2) there is sometimes a lack of distinct color and tonal contrast between a stabilized dune field and its surroundings.

The mapping with ERTS was evaluated by comparing the ERTS map with a similar map prepared using high-altitude aircraft photography. The comparison shows an impressive similarity.

The economic applications of the sand dune study are many. The vegetation growth on stabilized dunes was rated as having fair-to-good grazing potential depending upon the development of growth and amount of grazing usage the dunes displayed. The sand grains of various fields were of ideal sizes for production of fine-aggregate concrete material. There is also a potential for mining of glass sands. Archaeologists have used the sand dunes map as a source of information about dunal trends and possible archaeological site locations in efforts to find and interpret ancient artifacts and bone matter. Paleontologists note shifts of wind patterns over time and relate this to changing paleo and recent environments. Hydrologists have another application. Dune fields are excellent aquifers, so their potential as a water source is great. Finally, the use of wind as a potential energy source is a consideration. The wind map locates possible "belts" in which wind-powered generators may be most effective.

Geologic mapping using space images

ROBERT S. HOUSTON Department of Geology, University of Wyoming, Laramie, Wy. 82071

Pages
77-98

Keywords
ERTS, mapping, Skylab, geologic, aerial photography, satellite

Abstract
Many parts of the world, and even large areas within the United States are inadequately mapped. Interpretation of standard black-and-white photographs has traditionally been an important tool for the geologist. New data made available through the ERTS-1 satellite and other earth resources sensing programs can provide still more data for the geologist by allowing him to take advantage of the spectral characteristics of the rocks as an aid in mapping. Image enhancement techniques, such as ratioing, show potential for better and more quantitative analysis of the sensor data.

An example, using ERTS-1 imagery as a base for regional mapping of the Arminto area of central Wyoming, illustrates the advantages and limitations of the ERTS-1 data. Portions of the Arminto area were also mapped using Skylab and high-altitude aerial photography. Comparison of these maps with the Geologic Map of Wyoming (Love and others 1955) and the available detailed maps in the area reveals definite resolution limitations of the satellite data.

Color and synoptic coverage of broad areas are other important attributes of the ERTS satellite data. Skylab color photography has these advantages and the additional advantages of higher resolution and stereoscopic coverage. Aerial photography provides the additional detail necessary for accurate interpretation in geologically complex areas. Together, the ERTS, Skylab, and aircraft imagery provide an essential tool for geologic mapping that far exceeds the capability of standard aerial photography.

Evaluation of ERTS-1 imagery on the Tensleep Fault and southern Bighorn Basin, Wyoming

ALAN L. SWENSON Department of Geology, University of Iowa, Iowa City, Iowa 52242

Pages
99-104

Keywords
ERTS, Tensleep, Bighorn, Wyoming, linears, folds, mapping, structure

Abstract
ERTS-1 imagery was evaluated for use in photogeologic mapping, structural interpretations, and in detection of linears along the Tensleep fault and across the southern Bighorn basin. Photogeologic mapping was successful where stratigraphic contacts were expressed strongly topographically or tonally. Folds were accurately interpreted when they contained resistant "marker beds." Several linears, some related to geologic structures, others related to stratigraphy were detected. ERTS-1 imagery proved to be useful in large scale geologic studies.

Color anomalies, minerals, and ERTS imagery

R. W. MARRS Department of Geology, University of Wyoming, Laramie, Wy. 82071
R. M. BRECKENRIDGE Geological Survey of Wyoming, Box 3008, Laramie, Wy. 82071
R. S. HOUSTON Department of Geology, University of Wyoming, Laramie, Wy. 82071 FORREST K. ROOT Ge

Pages
105-110

Keywords
minerals, anomalies, ERTS, interpretations, copper, uranium

Abstract
The ERTS-I satellite imagery shows some potential for mapping color anomalies associated with copper and uranium mineralization. Interpreters attempting to define color anomalies by direct image interpretation often produce results that are only partially in agreement with other interpretations of the same images. Agreement among interpreters is generally fair to good with respect to the location of altered areas, but the interpretations seldom agree as to the boundaries of the anomalous zones. A similar relationship is observed when comparing the image interpretations to field maps of known areas of mineralization. Image enhancement procedures may improve the subtle color contrasts suffciently to allow accurate mapping of altered zones, but direct interpretation of the ERTS-I imagery has thus far proven useful only as a means of defining areas of interest to be studied in greater detail by other techniques.