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Unformatted text preview: PRELIMINARY TESTS OF THE UTILITY OF HYPERSPECTRAL IMAGE DATA TO PRECISION FARMING J. Garegnani, J. A. Gualtieri, S. Chettri, J. Robinson, J. P. Hunt, M. Bechdol, A. Vermeullen, Applied Information Sciences Branch, Code 935, NASA/GSFC, Greenbelt, MD 20771, U.S. Biospherics Science Branch, Code 923, NASA/GSFC, Greenbelt, MD 20771, U.S. Global Science and Technology Raytheon ITSS Science Systems and Applications, Inc email@example.com (301) 286-1079 / (301) 286-1776 fax 1. INTRODUCTION In a test of the utility of hyperspectral image data to precision farming, we have collected several inter-dependent data sets at an experimental farm on Maryland’s Eastern Shore during the 1999 growing season, focusing on weed identification in corn and soybean crop fields. These data included: hy- perspectral image data from an airborne instrument; ground feature location data collected with a differential GPS unit; geo-located radiometer and sun photometer measurements at ground level. In addition a database for the cost of all field inputs, materials and labor, was built to allow evaluation of the economic viability of incorporating hyperspectral data as an additional information source for precision farming. By collecting ground based radiometer and sun photome- ter measurements coincident with sensor over-flights, we were able to identify and partition sources of variation in the AISA image data so that target signals could be more accurately characterized. We used this to provide atmospheric correc- tion for our efforts to identify areas of weed infestation dur- ing the early stages of crop emergence. Later in the grow- ing season we used these methods for identifying different strains of crops in both maturing soybean and corn fields. 2. METHODS OF DATA COLLECTION Field experiments were conducted coordinating the AISA sen- sor flown aboard a twin engine Navaho aircraft by 3DI of Easton, MD with teams on the ground collecting radiomet- ric data. The field work was conducted at Chesapeake Farms on the Delmarva Peninsula near the town of Rock Hall, MD on May 28, July 8, and August 3, 1999. 2.1. The AISA sensor The work described here is based on data from the Airborne Imaging Spectrometer (AISA) built by Specim of Finland  and has a spectral range of 430 to 900 nm, a swath width of 286 pixels is imaged at a spatial resolution of 1m, 2m, and 3m for an aircraft flying at 1 km, 2 km, and 3 km respec- tively. In addition simultaneous down-welling irradiance is measured. The instrument orientation is monitored by an In- ertial Measurement Unit, and its position is recorded by GPS (Global Positioning Satellite). The data was geo-rectified to UTM coordinates and processed to both at sensor radiance measurements, and to at sensor reflectance, by ratioing the up-welling radiance to the down-welling radiance....
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