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COMBINING MULTIPLE SOURCES FOR RADIOMETRIC CALIBRATION OF 
LANDSAT 7 USING A KALMAN FILTER 
Ellis Freedman 
Jennifer Byme 
Martin Marietta Corporation 
Management and Data Systems 
1825, Washington Lane 
Meadwbrook, Pensylvania 19046, USA 
ISPRS Commission VII / Working Group 1 
ABSTRACT 
The Enhanced Thematic Mapper Plus, currently under development for Landsat 7, has a requirement to 
provide absolute radiometric information with errors of less than 5%. To meet this requirement, current 
plans call for the use of three different techniques for absolute radiometric calibration: Full Aperture 
Solar Calibration, Partial Aperture Solar Calibration, and Ground Look Calibration. Associated with each 
of these is its own set of uncertainties and errors which may, at times, exceed the system's sllowable 
error margin. A Kalman filter is proposed for cabining the outputs of all three techniques, and for the 
optimal estimation and continual updating and tracking of the states of the associated hardware 
calibrators. Results are presented which surpass the requirement and indicate the viability of the 
approach. 
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