This paper describes an application of the EM (expectation and maximisation) algorithm to the registration of incomplete millimetric radar images. The data used in this study consists of a series of nonoverlapping radar sweeps. Our registration process aims to recover transformation parameters between the radar-data and a digital map. The tokens used in the matching process are fragmented line-segments extracted from the radar images which predominantly correspond to hedge-rows in the cartographic data. The EM technique models data uncertainty using Gaussian mixtures defined over the positions and orientations of the lines. The resulting weighted least-squares parameter estimation problem is solved using the Levenberg-Marquardt method. A sensitivity analysis reveals that the date-likelihood function is unimodal in the translation and scale parameters. In-fact the algorithm is only sensitive to the choice of initial rotation parameter; this is attributable to local suboptima in the log-likelihood function associated with /spl pi//3 orientation ambiguities in the map. The method is also demonstrated to be relatively insensitive to random measurement errors on the line-segments.
Cartographic matching with millimetre radar images
1996-01-01
857756 byte
Conference paper
Electronic Resource
English
Cartographic Matching with Millimetre Radar Images
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