  In this paper we present a novel approach for representing and evolving
deformable active contours. The method combines piecewise regular B{\'e}zier
models and curve evolution defined by local Free Form Deformation. The contour
deformation is locally constrained which allows contour convergence with almost
linear complexity while adapting to various shape settings and handling
topology changes of the active contour.
  We demonstrate the effectiveness of the new active contour scheme for visual
free space perception and segmentation using omnidirectional images acquired by
a robot exploring unknown indoor and outdoor environments. Several experiments
validate the approach with comparison to state-of-the art parametric and
geometric active contours and provide fast and real-time robot free space
segmentation and navigation.
