A computer program undergoing development detects patterns that may differ in size but are otherwise similar to a specified pattern. Con- ceived to enable the automated recognition of features in images of planets and asteroids acquired by exploratory spacecraft, the program can also be used for scale-invariant recog- nition of patterns in other applications. The program requires no advance knowledge or mathematical modeling of a pattern to be recognized; instead, the program trains itself on one or more examples of a pattern provided by the user. The program synthesizes virtual examples by resampling the user-provided example(s) at different pixel spacings. The result of the resampling is a set of continuously scalable detectors, which can be regarded as implementing an extension of matched filtering (also known as template matching in the computervision and pattern-recognition literature), which was developed in the early 1940’s for radar and communication applications. The program has shown promise in tests on images of terrain of several astronomical bodies. For example, in the case of images of bowl-floored Lunar craters wider than 4 pixels, the program ex- hibited an 80-percent probability of detection and a 12-percent false-alarm rate.

This program was written by Michael C. Burl and Timothy Stough of Caltech for NASA’s Jet Propulsion Laboratory.

This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393- 3425. Refer to NPO-30269.

This Brief includes a Technical Support Package (TSP).
Software Recognizes Similar Patterns of Different Sizes

(reference NPO-30269) is currently available for download from the TSP library.

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This article first appeared in the July, 2002 issue of NASA Tech Briefs Magazine.

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