A Factorization Method for Affine Structure from Line Correspondences

A family of structure from motion algorithms called the factorization method has been recently developed from the orthographic projection model to the afJine camera model [23, i6, 181, All these algorithms are limited to handling only point features of the image stream. W e propose in this paper an algorithm for the recovery of shape and motion from line correspondences by the factorization method with the afJine camera. Instead of one step factorization for points, a multi-step factorization method is developed for lines based on the decomposition of the whole shape and m80tion into three separate substructures. Each of these substructures can then be linearly solved by factorizing the appropriate measurement matrices. I t is also established that a f i n e shape and motion with uncnlibrated a f i n e cameras can be achieved with a t least seven lines over three views, which extends the preuious results of Koenderink and Van Doorn [Q] for points to lines.