  We propose a pattern recognition method that identifies the common tangent
lines of a set of ellipses. The detection of the tangent lines is attained by
applying the Legendre transform on a given set of ellipses. As context, we
consider a hypothetical detector made out of layers of chambers, each of which
returns an ellipse as an output signal. The common tangent of these ellipses
represents the trajectory of a charged particle crossing the detector. The
proposed method is evaluated using ellipses constructed from Monte Carlo
generated tracks.
