Improvements in optical rangefinding technology have made it easy to acquire dense 3D samples of an object or scene. However, a fully automated procedure for assembling this data to create a geometric model still eludes us. This is especially true for large or complicated objects scanned under non-laboratory conditions. For example, although Stanford's Digital Michelangelo Project produced some nice models, it did not achieve many of its stated objectives.
In this talk, I briefly survey the unsolved problems of 3D scanning. For some of these problems, well defined solutions exist, and steady progress can be made on them. Examples of this type include calibration of scanning platforms, multi-view registration, surface reconstruction, view planning, and the handling of large datasets. For other problems, solutions exist but the problem is usually badly conditioned due to noise. Examples of this type include multi-view registration in the presence of scanner miscalibration, estimation of surface reflectance, and the scanning of optically uncooperative materials. In still other cases, the problem itself is ill-posed, admitting multiple correct answers. Classic examples of this type are surface reconstruction in the presence of missing data (i.e. holes), and estimation of surface shape and reflectance in the presence of interreflections or subsurface scattering. Finally, there are problems for which no good solutions exist, such as scanning geometrically convoluted objects, and insuring safety for the objects being scanned.
We end with a (mostly) upbeat assessement of the long-term prospects for 3D scanning and some predictions concerning its likely impact on industry, scholarship, and popular culture.
Biographical sketch:
Marc Levoy is an Associate Professor of Computer Science and (jointly) Electrical Engineering at Stanford University. He received a Bachelor's and Master's in Architecture from Cornell University in 1976 and 1978, and a PhD in Computer Science from the University of North Carolina at Chapel Hill in 1989. In the 1970's Levoy worked on computer animation, developing an early computer-assisted cartoon animation system. This system was used by Hanna-Barbera Productions from 1983 until 1996 to produce The Flintstones, Scooby Doo, and other shows. In the 1980's Levoy worked on volume rendering, a family of techniques for displaying sampled three-dimensional functions, for example computed tomography (CT) or magnetic resonance (MR) data. In the 1990's he worked on technology and algorithms for digitizing three-dimensional objects. This led to the Digital Michelangelo Project, in which he and a team of researchers spent a year in Italy digitizing the statues of Michelangelo using laser scanners. His current interests include sensing and display technologies, image-based modeling and rendering, and applications of computer graphics in art history, preservation, restoration, and archaeology. Awards: Charles Goodwin Sands Medal for best undergraduate thesis (1976), National Science Foundation Presidential Young Investigator (1991), ACM SIGGRAPH Computer Graphics Achievement Award (1996).