In this paper, we develop and study a robust algorithm for computing i
ntersections of two planar interval polynomial curves. The intersectio
n problems include well-conditioned transveral intersections as well a
s ill-conditioned cases such as tangential and overlapping intersectio
ns. Key components of our methods are the reduction of the intersectio
n problems into solving systems of nonlinear interval polynomial equat
ions which consist of m equations with n unknowns. An earlier interval
nonlinear polynomial solver for balanced system based on Bernstein su
bdivision method coupled with rounded interval arithmetic is extended
to solve unbalanced systems. The solver provides results with numerica
l certainty and verifiability. Examples illustrate our techniques. Cop
yright (C) 1996 Elsevier Science Ltd