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GRASP Lab Seminar 2003-2004
April 16, 11:00 AM, Levine Hall 307, hosted by CT Taylor.
Marc Pollefeys
University of North Carolina
Visual 3D Modeling using Cameras and Camera Networks
Abstract: This talk consists of two main parts. First, a fully automatic approach to reconstruct detailed 3D models from camera images is presented. The approach can deal with uncalibrated image sequences acquired with a hand-held camera. Based on tracked or matched features the relation between multiple views are computed. From this both the structure of the scene and the motion of the camera are retrieved. The ambiguity on the reconstruction is restricted from projective to metric through self-calibration. A flexible multi-view stereo matching scheme is used to obtain a dense estimation of the surface geometry. From the computed data detailed 3D surface models or alternative visual representations are constructed. Issues such as key-frame selection, dominant planes and camera auto-exposure are addressed. Next, the calibration and synchronization of camera networks is addressed. An efficient and robust algorithm that computes the epipolar geometry from silhouttes of dynamic objects is presented. This makes this approach particularly suitable for visual hull systems. Using the pairwise epipolar geometries, the complete calibration of the network is computed, and refined through bundle adjustment. A specific difficulty is that in general only two view matches are available (frontier points). This approach is also extended to deal with unsynchronized video streams. Ongoing efforts to extend this research to active pan-tilt-zoom camera networks is also briefly discussed.
Biography: Marc Pollefeys is an Assistant Professor of Computer Science at the University of North Carolina at Chapel Hill. He received his M.S. and Ph.D. degrees from the K.U.Leuven in 1994 and 1999, respectively. His main area of research is computer vision, more specifically multi-view geometry, structure from motion, (self-)calibration, stereo, image-based rendering and applications. One of his main research goals is to develop flexible approaches to capture visual representations of real world objects, scenes and events. Dr. Pollefeys has received several prizes for his research, including the prestigious Marr prize at ICCV '98. Recently he also obtained an NSF career award. He is the author or co-author of more than 70 technical papers. He has organized workshops and courses at major vision and graphics conferences. He has been serving on the program committees of major conferences such as ICCV, CVPR and ECCV and is a regular reviewer for most of the major vision, graphics and photogrammetry journals.
