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SIBGRAPI 2002. Combining Approximate Geometry with VDTM – A Hybrid Approach to 3D Video Teleconferencing Celso Kurashima 2 , Ruigang Yang 1 , Anselmo Lastra 1 1 Department of Computer Science University of North Carolina at Chapel Hill 2 Laboratório de Sistemas Integráveis - LSI
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SIBGRAPI 2002 Combining Approximate Geometry with VDTM – A Hybrid Approach to 3D Video Teleconferencing Celso Kurashima2, Ruigang Yang1, Anselmo Lastra1 1Department of Computer Science University of North Carolina at Chapel Hill 2Laboratório de Sistemas Integráveis - LSI Escola Politécnica da Universidade de São Paulo Fortaleza, October 8th, 2002
Introduction Video Conference 2D vs. 3D
Outline • 3D Video Teleconference System • Geometry Extraction • Rendering Images with VDTM • Results • Conclusion
3D Video Teleconference System (1/3) • Top View (A) (B)
3D-Video Teleconference System (3/3) • How does it work? • 1st: Create a geometry proxy of the person • 2nd: Texture map images onto the proxy with VDTM : an IBR method developed by Debevec et al.(’96, ’98)
Geometry Proxy Extraction (1/5) • The proxy : a simple geometric representation of the person • Mesh of triangles • Map textures onto the triangles faces • Extraction: a pair of cameras • May be two of texture cameras
Geometry Proxy Extraction (2/5) • Algorithm- Plane + Parallax (Kumar, 94) method: • Robust Plane Fitting • Stereo Feature tracking
Geometry Proxy Extraction (3/5) • Robust Plane Fitting • Segmentation • Points on the Silhouette • Matching • Fit Plane • Distance • Std. Dev. • Remove distant points • Repeat
Geometry Proxy Extraction (4/5) Stereo Feature TrackingKLT tracker (Kanade-Lucas-Tomasi, ‘91, ‘94)
Geometry Proxy Extraction (5/5) Triangulation & Proxy formation + =
Rendering Images with VDTM – View Dependent Texture Mapping (1/2) • VDTM requires a good spatial geometry of the objects (Debevec98) • Our system [ Buehler et al (2001) and Heigl et al (1999) ] Spatial geometry == proxy Textures == live images (from cameras) • Textures are mapped onto the proxy according to the viewpoint
Rendering Images with VDTM – View Dependent Texture Mapping (2/2) • Virtual Camera at Viewpoint D • Texture from cameras Ci mapped onto the triangles faces • Blending weights in vertex V • Angles qi, used to compute the weights values wi = exp(-qi2/2.s2)
Results (1/3) • Geometry Proxy & Image rendering with VDTM • Geometry Proxy • Image rendered with 2 texture cameras • Image rendered with 4 texture cameras
Results (2/3) • Cameras: Firewire IEEE 1394 SONY • Frame size: 320x240 pixels • Geometry/Renderer PC • Processor: Intel Pentium4, 2.2 GHz • Graphics card: nVidia GeForce3 • Video Frame Rate: 3-4 fps
Results (3/3) • 3D Video Teleconferencing Movie
Conclusions • A hybrid system for 3D Video Teleconferencing • Fast geometry proxy extraction, using a robust plane fitting method and stereo feature tracking, combined with view-dependent texture mapping • Real-time demonstration with personal computers and commodity graphics card
Future Work • Vision-based head-tracking for viewpoint control • Increase of the frame rate with faster segmentation
Acknowledgements • Herman Towles • Office of the Future (OOTF) group at UNC-CH • U.S. Dept. of Energy and Sandia National Labs. • U.S. National Science Foundation • NEC/CPDIA
Thank you! http://www.cs.unc.edu/Research/ootf/ http://www.lsi.usp.br/~kurash/