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Geoscience and Remote Sensing, IEEE Transactions on

Issue 2 • Date March 1986

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  • IEEE Transactions on Geoscience and Remote Sensing

    Publication Year: 1986 , Page(s): c1
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  • IEEE Geoscience and Remote Sensing Society

    Publication Year: 1986 , Page(s): c2
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  • Table of contents

    Publication Year: 1986 , Page(s): 189
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  • About the cover

    Publication Year: 1986 , Page(s): 190
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  • Performance Bounds for an Inverse Resistivity Problem

    Publication Year: 1986 , Page(s): 191 - 197
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    A procedure has been proposed for recovering a radially varying electrical resistivity profile from a particular series of dc electrical measurements. Such a procedure has potential applications to the study of the invasion of porous materials by electrically conductive fluids. This paper concerns the sensitivity of such a procedure to inaccuracies in the measurements. It is shown that, for a layered conductivity profile, the sensitivity of the conductivity estimates to measurement inaccuracy grow exponentially with the number of layers. This result indicates that resolution will be severely limited by measurement inaccuracy in the reconstruction of a conductivity profile from this particular series of dc electrical measurements. View full abstract»

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  • Transient Response from a Thin Sheet in a Conductive Medium for Loop Excitation

    Publication Year: 1986 , Page(s): 198 - 203
    Cited by:  Patents (2)
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    An analytical method to predict the electromagnetic step function response of a thin sheet anomaly in the Earth is given. Insight is provided for the characteristic form of the transient response of such a target. The method is an extension of Maxwell's original moving image solution to allow for a conductive background. The source is an arbitrary size insulated loop of current. Results show sensitivity to depth of burial and target conductivity-thickness product. The step function response can have a large bandwidth, and therefore is difficult to treat numerically. The results presented herein can therefore serve as a calibration test for more general numerical models. View full abstract»

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  • The Magnetotelluric Field for a Two-Dimensional Earth Modeled by a Nonuniform Buried Thin Sheet

    Publication Year: 1986 , Page(s): 204 - 211
    Cited by:  Papers (1)
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    Magnetotellurics (MT) is an electromagnetic sounding technique used in electrical geophysics to obtain information about the subsurface resistivity structure of the Earth. This information is then used to infer the presence of various natural resources such as oil accumulations and sources of geothermal energy. Extensive research has been done in the area of modeling and interpretation of the Earth in terms of one-dimensional Earth models. Difficulties in both modeling and interpretation occur when the conductivity structure of the Earth is allowed to vary laterally as well as vertically. This paper extends the analysis of a particular class of two-dimensional Earth models characterized by the "thin sheet" approximation. Integral equations are developed for the forward going problem of a plane wave normally incident on the surface of an Earth represented by a uniform half-space containing a thin sheet buried at an arbitrary depth and having an integrated conductivity that varies in one lateral direction. Both E perpendicular and E parallel polarization of the incident electric field are analyzed. The integral equations are evaluated numerically, and several example calculations are presented. View full abstract»

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  • Antenna Pattern Correction for the Nimbus-7 SMMR

    Publication Year: 1986 , Page(s): 212 - 219
    Cited by:  Papers (3)
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    This paper describes the philosophy and method used to develop the antenna pattern correction (APC) algorithm that was used on the data from the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7. There are limitations on what can be accomplished plished with such a procedure; these limitations are explored with the aid of Fourier analysis, even though the algorithm used on the SMMR data does not perform any Fourier transforms. The resulting analysis showed that, for the SMMR instrument, no useful improvement could be made in the data in terms of reduction of side lobes, but the quality of the sea surface temperature retrievals could be improved considerably by matching the antenna beamwidths at the different frequencies. View full abstract»

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  • A Study of the Microwave Brightness Temperature of Snow from the Point of View of Strong Fluctuation Theory

    Publication Year: 1986 , Page(s): 220 - 231
    Cited by:  Papers (18)
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    An application of strong fluctuation theory to the computation of the brightness temperature of dry and wet isothermal snowpacks is made. The numerical problems associated with computations are analyzed for the case of plane boundaries but arbitrary structure in the vertical direction. Comparisons of computed effective dielectric constants as well as brightness temperatures with experimental observations are made. The generally good agreement that is achieved does not depend on the arbitrary introduction of correction factors as is necessary when using radiative transfer theory. View full abstract»

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  • A Re-Examination of Radar Terrain Backscattering at Nadir

    Publication Year: 1986 , Page(s): 232 - 234
    Cited by:  Papers (2)
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    The theoretical behavior of nadir specular and diffuse radar backscattering from rough terrain is re-examined. Terrain is modeled as a random rough surface in the Kirchhoff approximation. The relative significance of specular (coherent) and diffuse (noncoherent) radar backscatter is compared in terms of the antenna system parameters (beamwidth, height, and frequency) and rough surface statistics. It has been found that in case of a high-altitude (space or airborne) radar, the ratio between coherent and noncoherent terrain backscatter is independent of its altitude of the radar platform. A possible explanation is suggested for the anomalous radar backscatter observed in the Skylab S-193 altimeter experiment. View full abstract»

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  • Textural Infornation in SAR Images

    Publication Year: 1986 , Page(s): 235 - 245
    Cited by:  Papers (161)
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    A multiplicative model was used to relate the image variance for a given land-use category to the individual variances associated with image speckle and target texture. Speckle was treated as a random process governed by signal fading and was considered to be statistically independent of the textural variations associated with the spatial variations of the scattering properties of visually "uniform" distributed targets. Seasat SAR imagery of Oklahoma was used to evaluate the textural autocorrelation function of five land-use categories: water, forest, pasture, urban, and cultivated. It was found that the maximum classification accuracy achievable using first-order statistics was 72 percent and that this level of accuracy was obtainable only by significantly degrading the spatial resolution in order to increase the number of independent samples per pixel. In contrast, second-order statistics-specifically, image contrast and inverse moment-provided a classification accuracy of 88 percent, with only a modest degradation in spatial resolution. A second study using SIR-A imagery of five forested regions has shown that the use of textural information can improve the classification accuracy among the five forest types from 75 to 93 percent. View full abstract»

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  • Multipolarization Radar Images for Geologic Mapping and Vegetation Discrimination

    Publication Year: 1986 , Page(s): 246 - 257
    Cited by:  Papers (9)
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    The NASA/JPL airborne synthetic aperture radar system produces radar image data simultaneously in four linear polarizations (HH, VV, VH, HV) at 24.6-cm wavelength (L-band), with 10-m resolution, across a swath width of approximately 10 km. The signal data are recorded optically and digitally and annotated in each of the channels to facilitate a completely automated digital correlation. Both standard amplitude, and also phase difference images are produced in the correlation process. Individual polarization and range-dependent gain functions improve the effective dynamic range, but as yet do not permit absolute quantitative measurements of the scattering coefficients. However, comparison of the relative intensities of the different polarizations in individual black-and-white and color composite images provides discriminatory mapping information. In the Death Valley, California, area, rough surfaces of young alluvial deposits produce strong responses at all polarizations. Smoother surfaces of older alluvial deposits show significantly lower responses. Evaporite deposits of different types and moisture contents have distinct polarization signatures. In the Wind River Basin, Wyoming, sedimentary rock units show polarization responses that relate to differences in weathering. Local intensity variations in like-polarization images result from topographic effects; strong cross-polarization responses denote the effects of vegetation cover and, in some cases, possible scattering from the subsurface. In the Savannah River Plant, South Carolina, forest cover characteristics are discriminated by polarization responses that reflect the density and structure of the canopy, and the presence or absence of standing water beneath the canopy. View full abstract»

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  • Assessment of Atmospheric Limitations on the Determination of the Solar Spectral Constant from Ground-Based Spectroradiometer Measurements

    Publication Year: 1986 , Page(s): 258 - 266
    Cited by:  Papers (5)
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    Ground-based solar radiometer measurements have long been used to investigate various properties of both the Earth's atmosphere and the sun. This paper addresses the problem of attempting to measure the solar spectral irradiance with heretofore unachieved levels of accuracy and precision (~0.5 and ~0.1 percent, respectively) via spectroradiometer measurements made at high-altitude ground stations. Instrumentation and calibration approaches are discussed, but attention is primarily directed toward assessing limitations imposed by the atmosphere. Assessments of factors such as diffuse light contributions, uncertainty in airmass determination, variability in atmospheric optical depth, spectroradiometer bandwidth, and data analysis methods are included in the paper. View full abstract»

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  • High Temporal-Resolution Infrared-Radiometric Observations of the Atmospheric Boundary Layer

    Publication Year: 1986 , Page(s): 267 - 280
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    An experiment designed to study the relationship of radiometric fluctuations to those of temperature and associated variables in the atmospheric boundary layer is described. Simultaneous and colocated observations were conducted by a ground-based infrared radiometer, fast response temperature, humidity, and wind sensors at 8 levels on the 300-m meteorological tower of the NOAA Boulder Atmospheric Observatory, an acoustic sounder, and a microbarograph array. The observed events included the arrival and development of a drainage flow, atmospheric waves, and convective plume activity. The analysis of the time series of the radiometer output compared with the directly measured meteorological variables and with the acoustic sounder record points out the potential of the ground-based radiometric technique for remote sensing of atmospheric fluctuation phenomena. View full abstract»

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  • Directional Reflectance Distributions of a Hardwood and Pine Forest Canopy

    Publication Year: 1986 , Page(s): 281 - 293
    Cited by:  Papers (39)
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    The directional reflectance distributions for both a hardwood and pine forest canopy at Beltsville, Maryland, were measured in June as a function of sun angle from a helicopter platform using a hand-held radiometer with AVHRR band 1 (0.58-0.68 ¿m) and band 2 (0.73-1.1 ¿m). Canopy characteristics were measured on the ground. The reflectance distributions are reported and compared to the scattering behavior of agricultural and natural grassland canopies. In addition, the three-dimensional radiative transfer model of Kimes was used to document the unique radiant transfers that take place in forest canopies due to their special geometric structure. Measurements and model simulations showed that the scattering behavior of relatively dense forest canopies is similar to the scattering behavior of agricultural crops and natural grasslands. Only in more sparse forest canopies with significant spacing between the tree crowns (or clumps of tree crowns) does the scattering behavior deviate from homogeneous agricultural and natural grassland canopies. This clumping of vegetation material has two effects on the radiant transfers within the canopy: A) it increases the probability of gap to the understory and/or soil layers that increases the influence of the scattering properties of these lower layers; and B) it increases the number of low transmitting clumps of vegetation within the scene causing increased backscatter and decreased forward scatter to occur relative to the homogeneous case. Both effects, referred to as phenomenon A and B, respectively, tend to increase backscatter relative to forward scatter. View full abstract»

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  • Noise in Remote-Sensing Systems: The Effect on Classification Error

    Publication Year: 1986 , Page(s): 294 - 300
    Cited by:  Papers (9)
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    Several types of noise in remote-sensing systems are treated. The purpose is to provide enhanced understanding of the relationship of noise sources to both analysis results and sensor design. The context of optical sensors and spectral pattern recognition analysis methods is used to enable tractability for quantitative results. First, the concept of multispectral classification is reviewed. Next, stochastic models are discussed for both signals and noise, including thermal, shot and quantization noise along with atmospheric effects. A model enabling the study of the combined effect of these sources is presented, and a system performance index is defined. Theoretical results showing the interrelated effects of the noise sources on system performance are given. Results of simulations using the system model are presented for several values of system parameters, using some noise parameters of the Thematic Mapper scanner as an illustration. Results show the relative importance of each of the noise sources on system performance, including how sensor noise interacts with atmospheric effects to degrade accuracy View full abstract»

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  • Storing Feature Descriptions as 2-D Trees

    Publication Year: 1986 , Page(s): 301 - 303
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    Many methods have been proposed which produce lowlevel features from digital images, e. g., the raw primal sketch or intrinsic images. However, in some cases the features occur sparsely in the image, and a more efficient storage scheme can be used than a registered array of feature images. Edges constitute one of the most useful sorts of information for scene analysis. Even though edge responses usually occur sparsely throughout an image, the output from an edge detector in most image analysis systems is itself an image of the same dimensions (but possibly multichannel) as the original intensity image. Appreciable savings in space and time can be achieved if the full edge descriptions (orientation, radius, and likelihood information) are stored as a 2-D tree. This is a binary tree which uses the (x, y) locations of the pixels as keys and splits the data at the median along the key with greatest spread (i. e., this is a k-d tree for k = 2). View full abstract»

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  • IEEE individual learning packages [advertisement]

    Publication Year: 1986 , Page(s): 303-a
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  • Information for authors

    Publication Year: 1986 , Page(s): 303b
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  • Institutional listings

    Publication Year: 1986 , Page(s): 303c
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Aims & Scope

 

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING (TGRS) is a monthly publication that focuses on the theory, concepts, and techniques of science and engineering as applied to sensing the land, oceans, atmosphere, and space; and the processing, interpretation, and dissemination of this information.

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Antonio J. Plaza
University of Extremadura