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The Area Coverage of Geophysical Fields as a Function of Sensor Field-of ViewIn many remote sensing studies of geophysical fields such as clouds, land cover, or sea ice characteristics, the fractional area coverage of the field in an image is estimated as the proportion of pixels that have the characteristic of interest (i.e., are part of the field) as determined by some thresholding operation. The effect of sensor field-of-view on this estimate is examined by modeling the unknown distribution of subpixel area fraction with the beta distribution, whose two parameters depend upon the true fractional area coverage, the pixel size, and the spatial structure of the geophysical field. Since it is often not possible to relate digital number, reflectance, or temperature to subpixel area fraction, the statistical models described are used to determine the effect of pixel size and thresholding operations on the estimate of area fraction for hypothetical geophysical fields. Examples are given for simulated cumuliform clouds and linear openings in sea ice, whose spatial structures are described by an exponential autocovariance function. It is shown that the rate and direction of change in total area fraction with changing pixel size depends on the true area fraction, the spatial structure, and the thresholding operation used.
Document ID
19970011954
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Key, Jeffrey R.
(Colorado Univ. Boulder, CO United States)
Date Acquired
August 17, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Remote Sensing the Environment
Publisher: Elsevier Science, Inc.
Volume: 48
ISSN: 0034-4257
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
NASA-CR-200177
NAS 1.26:200177
Accession Number
97N70876
Funding Number(s)
CONTRACT_GRANT: N00014-90-J-1840
CONTRACT_GRANT: NAGw-2407
CONTRACT_GRANT: NAGw-2598
Distribution Limits
Public
Copyright
Public Use Permitted.
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