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Airborne Hyperspectral Imagery for the Detection of Agricultural Crop StressMultispectral digital imagery from aircraft or satellite is presently being used to derive basic assessments of crop health for growers and others involved in the agricultural industry. Research indicates that narrow band stress indices derived from hyperspectral imagery should have improved sensitivity to provide more specific information on the type and cause of crop stress, Under funding from the NASA Earth Observation Commercial Applications Program (EOCAP) we are identifying and evaluating scientific and commercial applications of hyperspectral imagery for the remote characterization of agricultural crop stress. During the summer of 1999 a field experiment was conducted with varying nitrogen treatments on a production corn-field in eastern Nebraska. The AVIRIS (Airborne Visible-Infrared Imaging Spectrometer) hyperspectral imager was flown at two critical dates during crop development, at two different altitudes, providing images with approximately 18m pixels and 3m pixels. Simultaneous supporting soil and crop characterization included spectral reflectance measurements above the canopy, biomass characterization, soil sampling, and aerial photography. In this paper we describe the experiment and results, and examine the following three issues relative to the utility of hyperspectral imagery for scientific study and commercial crop stress products: (1) Accuracy of reflectance derived stress indices relative to conventional measures of stress. We compare reflectance-derived indices (both field radiometer and AVIRIS) with applied nitrogen and with leaf level measurement of nitrogen availability and chlorophyll concentrations over the experimental plots (4 replications of 5 different nitrogen levels); (2) Ability of the hyperspectral sensors to detect sub-pixel areas under crop stress. We applied the stress indices to both the 3m and 18m AVIRIS imagery for the entire production corn field using several sub-pixel areas within the field to compare the relative sensitivity of each stress index; and (3) Comparative sensitivity of stress indices to realistic measurement uncertainties. We compare the stress indices calculated with several levels of spectral uncertainty (by shifting the wavelengths) and reflectance uncertainty (by systematically varying the reflectance retrieval code initialization).
Document ID
20010100565
Acquisition Source
Headquarters
Document Type
Conference Paper
Authors
Cassady, Philip E.
(Boeing Co. Seattle, WA United States)
Perry, Eileen M.
(Battelle Pacific Northwest Labs. Richland, WA United States)
Gardner, Margaret E.
(California Univ. Santa Barbara, CA United States)
Roberts, Dar A.
(California Univ. Santa Barbara, CA United States)
Date Acquired
August 20, 2013
Publication Date
January 13, 2001
Publication Information
Publication: Hyperspectral Remote Sensing of the Land and Atmosphere
Volume: 4151
Subject Category
Earth Resources And Remote Sensing
Distribution Limits
Public
Copyright
Other

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