🚀 go-pugleaf

                    THE UNIVERSITY OF NORTH CAROLINA
                                   AT
                              CHAPEL HILL

                      COMPUTER SCIENCE DEPARTMENT

                      TWO TALKS ON IMAGE ANALYSIS


                        DEPARTMENT COLLOQUIUM

                     ALAN COLCHESTER, M.D., Ph.D.
                 Guys Hospital, University of London

A Unified Approach to the Segmentation of Grey-Level and Dot-Pattern Images

                       Monday, October 19, 1992
                    Rm. 011 Sitterson Hall at 3:30



Informal Talk:   GABOR SZEKELY, Ph.D.
                 Communications Techology Laboratory
                 ETH, Zurich, Switzerland

Title:  The Structure of the 3D Voronoi Diagram
        Used in Finding a Medial Surface of a 3D Object

Where:  Monday, October 19, 1992 at Image Lunch at 12:00
        Conference Area 284, Sitterson Hall

Abstract:  The Medial Axis Transformation was defined by Blum as a
continuous concept. Its implementation on a discrete raster suffers under
the requirement of agreeing with both a Euclide angeometry and a topology
based on a regular metric. One elegant way to resolve this contradiction
is using the Voronoi diagram of the boundary points as a superset of the
skeleton. The microscopic details on the boundary produce a vast amount
of 'noise branches' which should be pruned by appropriate algorithms. The
known pruning algorithms can be showed to be based on a recursive scheme
which relies heavily on the hierarchical branched structure of the 2D
Voronoi skeleton. When generalizing the skeleton generation to 3D, one can
try to solve the pruning problem by the same hierarchical approach. However,
due to the extra degree of freedom, the structure of the Voronoi diagram has
a much higher connectedness, resulting in heavily aggregated structures
instead of treelike branching. The talk will overview our present understanding
about the structure of 2D and 3D Voronoi diagrams and discuss the present
difficulties.

Host:  Dr. Stephen M. Pizer, 2-1768.  Refreshments will be served  at 4:30