3D Photography.ppt

5/1/2000 Deepak Bandyopadhyay / UNC Chapel Hill 5/1/2000 Graphics Research at UNC 3D Photography(Image-based Model Acquisition) “Analog” 3D photography ! “3D stereoscopic imaging” been around as long as cameras have Use camera with 2 or more lenses (or stereo attachment) Use stereo viewer to create impression of 3D Motivation Digitizing real world objects 3D Photography : Definition Sometimes called “3D Scanning” Use cameras and light to capture the shape appearance of real objects Shape == geometry (point sampling + surface reconstruction + fairing) Appearance == surface attributes (color/texture, material properties, reflectance) Final result = richly detailed model Applications in Industry Human body / head / face scans Avatar creation for virtual worlds 3d conferencing medical applications product design Platforms: Cyberware RD3030 Others (Geomagic, Metacreations, Cyrax, Geometrix…) More applications Historical preservation, dissemination of museum artifacts (Digital Michelangelo, Monticello, …) CAD/CAM (eg. Legacy motorcycle parts scanned by Geomagic for Harley-Davidson). Marketing (models of products on the web) 3D games simulation Reverse engineering Technology Overview The Imaging Pipeline Real World Optics Recorder Digitizer Vision Graphics Quick Notes on Optics Model lenses with all their properties - aberration, distortion, flare, vignetting etc. We correct for some of these effects (eg. distortion) in the calibration, ignore others. CCD (charged coupled devices) are the most popular recording media. Theory : Passive Methods Stereo pair matching Structure from motion Shape from shading Photometric stereo Stereo Matching Stereo Matching Basics Needs two images, like stereoscopy Given correspondence betweenpoints in 2 views, we can find depth by triangulation But correspondence is hard prob! A lot of literature on solving it… Structure from Motion Camera moving, objects static Compute camera motion and object geometry from motion of image point