Geology topics
Charles J. Robinove
Publications and source records attributed to Charles J. Robinove.
Some guidelines for remote sensing in hydrology
Remote sensing in the field of hydrology is beginning to be applied to significant problems, such as thermal pollution, in many programs of the Federal and State Governments as well as in operation of many private organizations. The purpose of this paper is to guide the hydrologist to a better understanding of how he may collect, synthesize, and interpret remote sensing data.
Effects of the atmosphere on the detection of surface changes from Landsat multispectral scanner data
The atmospheric effects on radiometric data recorded in the Landsat multispectral scanner system (MSS) bands are compiled for cases of representative and ideal atmospheric conditions. The effects are expressed as a difference between the Earth's surface spectral reflectivity, a 0 , and the surface-atmosphere system spectral reflectivity, a s , derived from the satellite data, a s −a 0 = −a 0 [l+(l/μ 0 )](B+W) + 2a 2 0 B + g(μ 0 )B/2μ 0 where μ 0 is the cosine of the solar zenith angle, B and W are the backscattering and absorption optical thickness respectively, and the function g( μ 0 ) is the anisotropy of backscattering to the zenith from the direct beam. This formula is accurate only for an atmosphere of low optical thickness. Also, the equation applies only to large areas having a uniform reflectivity, because adjacency effects due to reflection from the terrain surrounding the object pixel and subsequent scattering by the atmosphere are not considered. It is concluded that in the quantitative monitoring of surface changes from satellites, scattering effects predominate in some applications (for example, bathy-metric mapping of coastal waters), whereas absorption effects predominate in other applications (for example, monitoring desert fringe areas). Different measurements are more appropriate for assessing the scattering effects than for assessing the absorption effects. These effects on the monitoring of surface changes by the use of Landsat MSS data are discussed in terms of departures of the actual atmosphere at the time of a satellite passage from a ‘minima’ atmosphere having no aerosols and characterized by gaseous absorption corresponding to minimal water vapour amounts.
Arid land monitoring using Landsat albedo difference images
The Landsat albedo, or percentage of incoming radiation reflected from the ground in the wavelength range of 0.5 [mu]m to 1.1 [mu]m, is calculated from an equation using the Landsat digital brightness values and solar irradiance values, and correcting for atmospheric scattering, multispectral scanner calibration, and sun angle. The albedo calculated for each pixel is used to create an albedo image, whose grey scale is proportional to the albedo. Differencing sequential registered images and mapping selected values of the difference is used to create quantitative maps of increased or decreased albedo values of the terrain. All maps and other output products are in black and white rather than color, thus making the method quite economical. Decreases of albedo in arid regions may indicate improvement of land quality; increases may indicate degradation. Tests of the albedo difference mapping method in the Desert Experimental Range in southwestern Utah (a cold desert with little long-term terrain change) for a four-year period show that mapped changes can be correlated with erosion from flash floods, increased or decreased soil moisture, and increases or decreases in the density of desert vegetation, both perennial shrubs and annual plants. All terrain changes identified in this test were related to variations in precipitation. Although further tests of this method in hot deserts showing severe "desertification" are needed, the method is nevertheless recommended for experimental use in monitoring terrain change in other arid and semiarid regions of the world.
The logic of multispectral classification and mapping of land
The use of multispectral reflectance data as surrogates for land attributes must be done within strict rules of logic and with a recognition of judgmental factors such as the use of a priori or a posteriori classification schemes. The naming and describing of spectral classes as surrogates of information classes is a critical element in the logic of mapping and must be complete and logically consistent. Maps of information classes derived from multispectral data should be portrayed without class boundaries so as to indicate the degree of homogeneity or heterogeneity of classes on maps in which these characteristics are of major importance.
Annotated bibliography of remote sensing methods for monitoring desertification
Remote sensing techniques are valuable for locating, assessing, and monitoring desertification. Remotely sensed data provide a permanent record of the condition of the land in a format that allows changes in land features and condition to be measured. The annotated bibliography of 118 items discusses remote sensing methods that may be applied to desertification studies.
Interpretation of a Landsat image of an unusual flood phenomenon in Australia
A Landsat image of part of the flooded area of Cooper Creek, Queensland, Australia, in February 1974, shows large dark areas within the flooded valley. The dark areas are believed to be wet, but unflooded, areas of dark alluvial soil. These striking features, which have not previously been identified on Landsat images, must be properly interpreted so as not to confuse them with clear water.
Use of a remote computer terminal during field checking of Landsat digital maps
Field checking of small-scale land classification maps made digitally from Landsat data is facilitated by use of a remote portable teletypewriter terminal linked by teleplume to the IDIMS (Interactive Digital Image Manipulation System) at the EDC (EROS Data Center), Sioux Falls, S. Dak. When field checking of maps 20 miles northeast of Baker, Calif., during the day showed that changes in classification were needed, the terminal was used at night to combine image statistical files, remap portions of images, and produce new alphanumeric maps for field checking during the next day. The alphanumeric maps can be used without serious difficulty in location in the field even though the scale is distorted, and statistical files created during the field check can be used for full image classification and map output at the EDC. This process makes field checking faster than normal, provides interaction with the statistical data while in the field, and reduces to a minimum the number of trips needed to work interactively with the IDIMS at the EDC, thus saving significant amounts of time and money. The only significant problem is using telephone lines which at times create spurious characters in the printout or prevent the line feed (paper advance) signal from reaching the terminal, thus overprinting lines which should be sequential. We recommend that maps for field checking be made with more spectral classes than are expected because in the field it is much easier to group classes than to reclassify or separate classes when only the remote terminal is available for display.
A radiometric interpretive legend for Landsat digital thematic maps
A legend is suggested for use with computer-generated thematic maps made from Landsat digital data that designates some of the radiometric characteristics of each thematic map unit as well as the described terrain attributes of each map unit. The relationship between spectral band and radiance for each map unit is shown by a two-dimensional polygon with the four Landsat multispectral scanner bands plotted on the ordinate and radiance levels on the abscissa. The resulting shape is colored to correspond with the map unit color, thus facilitating the recognition and understanding of the computer-generated map units.
Value and validity of earth resources observations from space
Observations of the earth from space can provide overall repetitive views in various regions of the electromagnetic spectrum. Data from such surveys can be used as the basis for more detailed observations from aircraft and on the ground to guide resource exploration, development, and conservation activities. The value of earth resource observations from space has been demonstrated by the practical use of photographs from the Gemini and Apollo spaceflights and particularly by a series of multispectral photographs taken during the flight of Apollo 9. The analysis of those photographs has shown that the performance of the planned Earth Resources Technology Satellite will meet the needs of the resource and environmental community for small-scale repetitive images of the earth in the visible and solar infrared portions of the spectrum and has provided a limited base of material for earth scientists to work with in order to ready themselves for the ERTS data. The validity of earth resource observations from space can be derived by analogy from the successively closer observations of the moon, culminating in repeated physical sampling of the moon's surface. The method of inductive reasoning and analysis used for the moon is the opposite of the normal deductive analysis used on the earth. Adoption of the inductive methods and reasoning for earth observations will provide a framework of broad observations and conclusions leading to the identification of target areas for more detailed observation and will, in time, reduce the costs and time required for surveys dealing with resource and environmental problems.
Perception via satellite
The earth resources observation satellite (EROS) program in the Department of the Interior is intended to gather and use data from satellites and aircraft on natural and man-made features of the earth's surface. Earth resources technology satellite will provide the EROS program with data for use in dealing with natural resource problems and understanding the interaction between man and the environment. Applications will include studies of tectonic features, hydrologic problems, location of fish schools, determination of the conditions of range land, mapping land use for urban planning, studies of erosion and change along coastlines and major streams, and inventories of land use and land forms. In addition, the ERTS data may be used for detecting forest and crop diseases and inventorying crops. The ERTS satellite will be in a polar, sun-synchronous orbit so that each point on the earth's surface will be sensed every 17 to 20 days, at the same time of day. Multispectral photography is being investigated for its usefulness in hydrology. Side-looking airborne radar has not yet been widely used in hydrologic studies, although it is an excellent tool for all-weather, day or night, coverage of large areas. Other techniques being investigated include passive microwave radiometry, ultraviolet and visible stimulated luminescence, and absorption spectroscopy.
Infrared photography and imagery in water resources research
This article briefly describes the characteristics of infrared radiation and demonstrates how infrared photography and infrared imagery can be applied to water resources research, specifically to the identification and description of hydrologic features.
Photography and imagery: a clarification of terms
The increased use of pictorial displays of data in the fields of photogrammetry and photo interpretation has led to some confusion of terms, not so much b photogrammetrists as bu users and interpreters of pictorial data. The terms "remote sensing" and "remote sensing of environment" are being used as general terms to describe "the measurement of some property of an object without having the measuring device physically in contact with the object" (Parker, 1962). Measurements of size and shape by photogrammetric and optical means are common examples of remote sensing and therefore require no elaboration. Other techniques of remote sensing of electromagnetic radiation in and beyond the limits of the visible spectrum require some explanation and differentiation from the techniques used in the visible spectrum. The following definitions of "photography" and "imagery" are proposed to clarify these two terms in hope that this will lead to more precise understanding and explanation of the processes.