title: A contour propagation approach to surface filling-in and volume formation.
abstract: A new approach to surface and volume formation is introduced in response to the question, "Why do some silhouettes look 3 dimensional (3D) and others look 2D?" The central idea is that form information can propagate away from a "propagable segment" (PS) of occluding contour that could have projected onto the image from the visible portion of a cross-section of a surface. A key property of a PS is that it exhibits abrupt curvature changes where it meets the rest of the occluding contour. An algorithm is described for filling in curved surfaces from a PS: When copies of a PS are propagated into the interior, they act as cross-sectional surface contours that also exhibit abrupt curvature changes with the rest of the occluding contour. The result is a nonmetric coding of 3D-shape in terms of local ordinal surface curvature and orientation relationships that is scale, translation, and rotation invariant.
authors.affiliation: Max Planck Institute for Biological Cybernetics, Tübingen, Germany. peter.tse@dartmouth.edu
authors.forename: Peter Ulric
authors.initials: PU
authors.lastname: Tse
mesh_terms: D000465:Algorithms; D006801:Humans; D008962:Models, Theoretical; D012160:Retina / Q000502:physiology; D013028:Space Perception / Q000502:physiology*