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Proceedings Paper

Minimization-pruning algorithm for finding elliptical boundaries in images with nonconstant background and with missing data
Author(s): Domingo A. Mihovilovic; Ramin Samadani
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Paper Abstract

The DE-1 satellite has gathered over 500,000 images of the Earth's aurora using ultraviolet and visible light photometers. The extraction of the boundaries delimiting the auroral oval allows the computation of important parameters for the geophysical study of the phenomenon such as total area and total integrated magnetic field. This paper describes an unsupervised technique that we call 'minimization-pruning' that finds the boundaries of the auroral oval. The technique is based on concepts that are relevant to a wide range of applications having characteristics similar to this application, namely images with variable background, high noise levels and missing data. Among the advantages of the new technique are the ability to find the object of interest even with intense interfering background noise, and the ability to find the outline of an object even if only a section of it is visible. The technique is based on the assumption that certain regions of the object are less obscured by the background, and hence the information provided by these regions is more important for finding the boundaries. The implementation of the technique consists of an iterative minimization-pruning algorithm, in which a fundamental part is a measure of the quality of the data for different regions along the boundary. Calculation of this measure is simplified by transforming the input image into polar coordinates. The technique has been applied to a set of more than 100 images of the aurora with good results. We also show examples of extraction of the inner and outer boundaries starting from the elliptical approximation and analyzing the image locally around that solution.

Paper Details

Date Published: 19 May 1992
PDF: 12 pages
Proc. SPIE 1657, Image Processing Algorithms and Techniques III, (19 May 1992); doi: 10.1117/12.58358
Show Author Affiliations
Domingo A. Mihovilovic, Stanford Univ. (United States)
Ramin Samadani, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 1657:
Image Processing Algorithms and Techniques III
James R. Sullivan; Benjamin M. Dawson; Majid Rabbani, Editor(s)

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