This paper presents a new method for computing optimal L1
solutions for vision geometry problems, particularly for those
problems of fixed-dimension and of large-scale. Our strategy for
solving a large L1 problem is to reduce it to a finite set of smallest
possible subproblems. By using the fact that many of the problems
in question are pseudoconvex, we prove that such a reduction is
possible. To actually solve these small subproblems efficiently, we
propose a direct approach which makes no use of any convex optimizer
(e.g. SOCP or LP), but is based on a simple local Newton
method. We give both theoretic justification and experimental validation
to the new method. Potentially, our new method can be
made extremely fast.