Guidance System Position Update By Multiple Subarea Correlation

Thomas K. Lo; Gordon Gerson

doi:10.1117/12.957496

4 September 1979 Guidance System Position Update By Multiple Subarea Correlation

Thomas K. Lo, Gordon Gerson

Proceedings Volume 0186, Digital Processing of Aerial Images; (1979) https://doi.org/10.1117/12.957496
Event: 1979 Huntsville Technical Symposium, 1979, Huntsville, United States

Abstract

Correlation is a common and powerful method for updating inertial guidance systems. Performance of correlation methods degrades in the presence of geometric distortion between the images being correlated, or when the image structure is strongly asymmetric. The Multiple Subarea Correlation (MSC) technique has been developed to reduce performance losses due to these effects. The MSC technique consists of selecting a set of subareas from the reference image, and correlating each reference subarea against the sensed image, producing a correlation function for each subarea. There must be at least three subareas; typically six subareas are selected. The correlation functions are processed to determine a consistent set of local maxima which are in gross agreement as to the relative displacement of the two images. Then, using this set of local maxima and the known subarea locations, a least-squared-error estimate of an affine transformation between the two images is computed. The transformation is applied to the update point in the reference image to find the corresponding point in the sensed image. The technique allows selection of subareas with the most favorable content for correlation. Optimum subarea dimensions exist and depend upon the amount of distortion expected. The variance of the update point position is shown to be inversely proportional to the number of subareas.

Citation Download Citation

Thomas K. Lo and Gordon Gerson "Guidance System Position Update By Multiple Subarea Correlation", Proc. SPIE 0186, Digital Processing of Aerial Images, (4 September 1979); https://doi.org/10.1117/12.957496

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