VASC Seminar Announcement
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Date: Monday, 3/1/99
Time: 3:30-4:30
Place: Smith Hall 2nd Floor Common Area

Speaker: Ronen Basri
         The Weizmann Institute, Israel

Title:  Object Recognition with Regions

Abstract: 

A central problem in recognition is to find representations that are
rich enough to capture the shape of complex objects and that have useful
analogs that can be computed reliably from images.  Existing approaches
only partially address these problems.  For example, local geometric
features (e.g.. corners, lines) may fail to capture the shape of
non-polyhedral objects.  Representations based on algebraic descriptions
of object parts (e.g.. generalized cylinders, superquadrics) may be
difficult to reliably compute in images, and it may be hard to relate a
3-D model to its 2-D appearance.  

Our work uses a simple direct representation of object parts and image
regions as sets of points.  This representation can clearly be applied
to a wide class of objects; what is surprising is that we can use such a
simple representation to recognize objects.  We focus on the central
problem of determining the position in an image of a known object. Our
approach assumes that we have matched regions of an image to parts of an
object model, without forming any explicit correspondences between local
geometric features or portions of contours.  We consider planar objects
and 3-D objects with three types of occlusions: self-occlusion,
occlusions whose locus is identified in the image, and completely
arbitrary occlusions.  We derive efficient algorithms for pose
determination in all cases except 3-D objects with arbitrary occlusion. 
For that case, we prove that the problem of finding valid poses is
computationally hard, but provide an efficient, approximate algorithm.

Joint work with: David Jacobs


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