SLIDE - SUBSPACE-BASED LINE DETECTION

An analogy is made between each straight line in an image and a planar propagating wavefront impinging on an array of sensors so as to obtai n a mathematical model exploited in recent high resolution methods for direction-of-arrival estimation in sensor array processing. The new s o-called SLIDE (Subspace-Based Line Detection) algorithm then exploits the spatial coherence between the contributions of each line in diffe rent rows of the image to enhance and distinguish a signal subspace th at is defined by the desired line parameters. SLIDE yields closed-form and high resolution estimates for line parameters, and its computatio nal complexity and storage requirements are far less than those of the standard method of the Hough transform. If unknown a priori, the numb er of lines is also estimated in the proposed technique. The signal re presentation employed in this formulation is also generalized to handl e grey-scale images as well. The technique has also been generalized t o fitting planes in 3-D images. Potential application areas of the pro posed technique include road tracking in robotic vision, mask-wafer al ignment and linewidth measurement in semiconductor manufacturing, aeri al image analysis, text alignment in document analysis, particle track ing in hubble chambers, and similar applications.