Abstract.
Efficient direct solutions for the determination of a cylinder from points are presented. The solutions range from the well known di- rect solution of a quadric to the minimal solution of a cylinder with five points. In contrast to the approach of G. Roth and M. D. Levine (1990), who used polynomial bases for representing the geometric entities, we use algebraic constraints on the quadric representing the cylinder. The solutions for six to eight points directly determine all the cylinder pa- rameters in one step: (1) The eight-point-solution, similar to the esti- mation of the fundamental matrix, requires to solve for the roots of a 3rd-order-polynomial. (2) The seven-point-solution, similar to the six- point-solution for the relative orientation by J. Philip (1996), yields a linear equation system. (3) The six-point-solution, similar to the five- point-solution for the relative orientation by D. Nister (2003), yields a ten-by-ten eigenvalue problem. The new minimal five-point-solution first determines the direction and then the position and the radius of the cylinder. The search for the zeros of the resulting 6th order polynomials is efficiently realized using 2D-Bernstein polynomials. Also direct solu- tions for the special cases with the axes of the cylinder parallel to a coordinate plane or axis are given. The method is used to find cylinders in range data of an industrial site.