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Optical Engineering

Measurement Of The Landsat Thematic Mapper Modulation Transfer Function Using An Array Of Point Sources
Author(s): Robert F. Rauchmiller; Robert A. Schowengerdt
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Paper Abstract

As part of the Landsat Thematic Mapper (TM) engineering evaluation effort, there have been several studies to measure a modulation transfer function (MTF). In contrast to work that measured or modeled only the optical and electronic components of the MTF, our goal was to measure the complete imaging system MTF from actual imagery. Measurements of the TM MTF using targets of opportunity have been reported previously. This paper describes new results using a specially designed target. To arrive at an estimate of the system MTF, the TM point spread function (PSF) was measured using a two-dimensional array of black squares constructed at the White Sands Missile Range in New Mexico. The design of the target creates 1/4-pixel shifts of "point sources" throughout the 30-m instantaneous field of view (IFOV) of the TM. This shifting allows exploitation of sample-scene phasing to effectively resample the PSF at a 7.5-m sample interval and thereby avoid aliasing in the MTF. A method for sorting the image data and "assembling" a PSF and a technique for correcting the rotation of the target relative to the sensor scan direction are discussed. A technique for partial elimination of variations in the scene background also is presented. The resulting estimates of the TM imaging system MTF compare favorably with the MTF predicted from a system model.

Paper Details

Date Published: 1 April 1988
PDF: 10 pages
Opt. Eng. 27(4) doi: 10.1117/12.7976678
Published in: Optical Engineering Volume 27, Issue 4
Show Author Affiliations
Robert F. Rauchmiller, Environmental Research Institute of Michigan (United States)
Robert A. Schowengerdt, University of Arizona (United States)


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