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Geoscience and Remote Sensing, IEEE Transactions on

Issue 6 • Date Nov 1989

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Displaying Results 1 - 19 of 19
  • Phase calibration of polarimetric radar images

    Publication Year: 1989 , Page(s): 719 - 731
    Cited by:  Papers (30)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1506 KB)  

    The problem of phase calibration between polarization channels of an imaging radar is studied. The causes of various types of phase errors due to the radar system architecture and system imperfections are examined. A simple model is introduced to explain the spatial variation in phase error as being due to a displacement between the phase centers of the vertical and horizontal antennas. It is also shown that channel leakage can cause a spatial variation in phase error. Phase calibration using both point and distributed ground targets is discussed and a method for calibrating phase using only distributed target is verified, subject to certain constraints. Experimental measurements using the NADC/ERIM P-3 synthetic-aperture radar (SAR) system and NASA/JPL DC-8 SAR, which operates at C-, L-, and P-bands, are presented. Both of these systems are multifrequency, polarimetric, airborne, SAR systems. View full abstract»

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  • Investigations of the Cerro Colorado Pluton, Northern Chile using enhanced Landsat Thematic Mapper images

    Publication Year: 1989 , Page(s): 746 - 753
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1638 KB)  

    Digitally enhanced Landsat Thematic Mapper (TM) images of the Cerro Colorado Pluton, Northern Chile, were studied. The bulk of the intrusion is magnetic-rich and laboratory spectra of the fresh surfaces of field samples are severely quenched. Weathering and oxidation of the magnetite has reduced the quenching effects, allowing features due to the primary mineralogy of the rock to be resolved in the spectra of the weathered surfaces and, consequently, on the enhanced imagery. In most cases the weathering alters the overall albedo of the rock and it may introduce additional features into the rock spectra due to iron hydroxides and clay minerals. As yet it does not seem to the author that TM data alone could be used for lithological mapping. Some control is necessary, in the form of fieldwork or pre-existing maps. View full abstract»

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  • Estimation of the SAR system transfer function through processor defocus

    Publication Year: 1989 , Page(s): 702 - 708
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1312 KB)  

    It is generally accepted that in order to derive wave directional spectra from synthetic-aperture radar (SAR) image data, the system transfer function (STF) must be removed from the raw SAR image spectrum. The STF, very nearly equivalent to the magnitude of the Fourier transform of the N-look perfect-focus impulse response, can be estimated from actual SAR image data as the magnitude of the Fourier transform of the autocorrelation function of the speckle in a low-contrast scene. The authors outline and demonstrate a novel approach for estimating the STF based on the observation that system defocus, to the first order, does not impact speckle statistics. View full abstract»

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  • A spectral feature design system for the HIRIS/MODIS era

    Publication Year: 1989 , Page(s): 681 - 686
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (926 KB)  

    A spectral feature design system for high-dimensional multispectral data is described. This system utilizes hard-limited or infinitely clipped optimal transforms and canonical analysis to extract the spectral features for data volume reduction and classification purposes. The design procedure is intended to be application-specific in order to make it maximally effective for each use. Although it could be used in a variety of circumstances, the procedure was designed with satellite data collection in mind, such as will be needed with the High-Resolution Imaging Spectrometer (HIRIS), a land-oriented Earth observational sensor intended for launch in the mid-1990s. The tests reported provide substantial data volume reduction in the satellite-to-Earth downlink and subsequent computation phases, while maintaining satisfactory classification accuracy. View full abstract»

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  • Analysis of multiple geological datasets from the English Lake District

    Publication Year: 1989 , Page(s): 732 - 739
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1873 KB)  

    A geological database comprising coregistered Landsat Thematic Mapper (TM) regional multielement stream sediment geochemistry, regional gravity and aeromagnetics, and geological map data has been established, in raster format, for the area of the English Lake District. To study spatial correlations within the database, TM imagery and its first-order structurally enhanced filter derivatives are combined with regional survey data using intensity-hue-saturation transforms and stereoscopic-view generation techniques. These are then overlaid with line and polygon information from other exploration datasets. Datasets are combined in a manner which maintains the identity of each dataset. The imagery produced demonstrates the power of image presentation for efficient multidata analysis. View full abstract»

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  • The wavefront shape, position, and evolution of a great solitary wave of translation

    Publication Year: 1989 , Page(s): 658 - 665
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1223 KB)  

    Doppler radar mapped the evolution of a pair of atmospheric solitary waves emanating from a thunderstorm complex. The 100-km-long curved wavefront and position of these few-kilometer-wide waves are hypothesized to be a result of an amplitude-dependent wave speed. The observed unfolding is compared with a solution of the nonlinear integro-differential equation governing the evolution of finite amplitude disturbances in stratified media. View full abstract»

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  • Monitoring salt playa dynamics using Thematic Mapper data

    Publication Year: 1989 , Page(s): 754 - 761
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1226 KB)  

    Various image analysis techniques have been applied to multitemporal Landsat Thematic Mapper data collected over a four-year period. The results have been used to monitor sediment transport processes in semi-arid south central Tunisia. Process-domains on salt playas in the study area have been identified and mapped. Seasonal, interseasonal, and spatial changes on these playas have been related to sediment, salt, and moisture regimes. Surface water and groundwater activity, and eolian processes, are identified as important sediment, transport processes. The observations bring into question the traditional groundwater-based model of salt playa geochemistry; a revised set of integrated geochemical/geomorphological models is invoked. View full abstract»

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  • Average areal water equivalent of snow in a mountain basin using microwave and visible satellite data

    Publication Year: 1989 , Page(s): 740 - 745
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (922 KB)  

    Satellite microwave and millimeter-wave data have been used to evaluate the average areal water equivalent of snow cover in the mountainous Rio Grande basin in Colorado. Areal water equivalent data for the basin were obtained from contoured values of point measurements and from elevation-zone water volume values generated by a reliable snowmelt-runoff model using data on visible snow-cover extent. A significant relationship between the difference in brightness temperature at two different frequencies (37 and 18 GHz) and a basin-wide average snow-water equivalent value was obtained. This relationship and microwave observations were used to estimate the average areal water equivalent of the snow cover. View full abstract»

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  • Simulation of optical remote sensing systems

    Publication Year: 1989 , Page(s): 762 - 771
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1230 KB)  

    Research on understanding the remote-sensing process as a system and investigating the interrelated effects of various parameter is described. A system model for the simulation of remote-sensing systems is presented. The system is divided into three parts: the scene, the sensor, and the processing algorithms. Models are presented and implemented for these component systems. Validation of the system model is considered over a specific test site. Results of the simulation for various scene and sensor configurations are included. Results of applying the model to various system configurations using simulated Landsat sensors are then presented to show how the simulation can be used to investigate the interrelated effects of system parameters. View full abstract»

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  • Complex SAR imagery and speckle filtering for wave imaging

    Publication Year: 1989 , Page(s): 666 - 673
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1054 KB)  

    A method is described to predict the wavenumber dependence of the speckle component in spectra of synthetic aperture radar intensity images. Filtering of this component is an important step in recovering waveheight spectra for synthetic-aperture radar (SAR) images of the ocean, and an effective means of doing so is required for the 'wave mode' of the European satellite ERS-1. The method uses the correlation function of the corresponding complex images and has been tested using a variety of airborne and spaceborne imagery obtained over both land and sea. Examples are shown of both successful and unsuccessful applications of the method. View full abstract»

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  • Segmentation of SAR images

    Publication Year: 1989 , Page(s): 674 - 680
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1470 KB)  

    Based on an SAR speckle statistical model, the authors investigate the feasibility of segmenting SAR images based on a gray-level histogram for one-look and multilook processed SAR images. The classification errors are evaluated and a procedure for the multilevel thresholding of SAR images is devised. The misclassification probabilities for one-look and four-look processed images are calculated and presented, and an unsupervised segmentation algorithm is given. A simulated one-look intensity image and a four-look SIR-B amplitude image are used for illustration. View full abstract»

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  • Seasat over-land scatterometer data. II. Selection of extended area and land-target sites for the calibration of spaceborne scatterometers

    Publication Year: 1989 , Page(s): 779 - 788
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2022 KB)  

    For pt.I see ibid., vol.27, no.5, p.592-605 (1989). The post-launch performance verification for future scatterometers can use extended area land targets to calibrate antenna gain patterns and to verify and monitor deployment configurations. For the Ku-band Seasat scatterometer, a region of tropical rain forest in the Amazon basin was used as a homogeneous extended-area land target. As this region is continuously being deforested, other regions are investigated for calibrating scatterometers. The global backscatter coefficients ( sigma 0) are compared to classifications of natural vegetation and cultivation intensity and the variability with the time during the three-month mission is studied. The statistical variability of sigma 0 is compared with prior estimates resulting from the known variability of the instrument parameters and communication noise. Data from selected forested regions with relatively homogeneous sigma 0 and little time-dependence are presented. View full abstract»

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  • Comments, with reply, on "Electric field sensors in electromagnetic sounding" by Wu Xiao Wu and David V. Thiel

    Publication Year: 1989 , Page(s): 789 - 792
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (133 KB)  

    The conclusion by W.X. Wu and D.V. Thiel (see ibid., vol.27, p.24-27, Jan. 1989) that a horizontal, insulated, ungrounded antenna is a dependable probe for the horizontal E fields is questioned. It is shown that the horizontal insulated antenna should be grounded at the end points to provide a reliable measurement of the actual surface impedance in conjunction with the measurement of the horizontal magnetic field. Wu and Thiel's experimental data supports this contention. In their first reply the original authors offer arguments and counterexamples to further support their case. In further comments J.R. Wait states that he has not altered his views on the matter as expounded in the letter. In a second reply Wu and Thiel elaborate on experimental details omitted in the original work, which it is hoped will clarify the previous explanations they presented.<> View full abstract»

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  • Leaf-shape effects in electromagnetic wave scattering from vegetation

    Publication Year: 1989 , Page(s): 687 - 697
    Cited by:  Papers (43)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1397 KB)  

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  • Measurement of microwave backscatter from a cypress with and without leaves

    Publication Year: 1989 , Page(s): 698 - 701
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (770 KB)  

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  • Multitemporal and dual-polarization observations of agricultural vegetation covers by X-band SAR images

    Publication Year: 1989 , Page(s): 709 - 718
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1789 KB)  

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  • Comarison between the microwave emissivity and backscatter coefficient of crops

    Publication Year: 1989 , Page(s): 772 - 778
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (991 KB)  

    First Page of the Article
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  • Author index

    Publication Year: 1989 , Page(s): 1 - 4
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    Freely Available from IEEE
  • Subject index

    Publication Year: 1989 , Page(s): 4 - 10
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    Freely Available from IEEE

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.

 

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Meet Our Editors

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