Accession Number : ADA258636


Title :   Implementation and Evaluation of a Three-Dimensional Photometric Sampler,


Corporate Author : CARNEGIE-MELLON UNIV PITTSBURGH PA SCHOOL OF COMPUTER SCIENCE


Personal Author(s) : Sato, Hideichi ; Nayar, Shree K ; Ikeuchi, Katsushi


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a258636.pdf


Report Date : Jul 1992


Pagination or Media Count : 54


Abstract : The photometric sampling method extracts shape and reflectance properties of surfaces (Lambertian, specular, and hybrid) by using multiple illumination directions and a single viewing direction. In this paper, we describe a complete implementation and a performance evaluation of a three- dimensional version of the photometric sampler. All existing shape extraction techniques that are based on photometric measurements rely on assumed surface reflection properties. We proposed a method for determining the shape of surfaces whose reflectance properties may vary from Lambertian to specular without prior knowledge of the relative strengths of the Lambertian and specular components of reflection. The object surface is illuminated using extended light sources and is viewed from a single direction. Extended light sources make it possible to ensure the detection of both Lambertian and specular reflections. Extended sources are generated by illuminating a diffuser with a point source of light. In the 3D implementation of the photosampler, multiple extended sources are generated by distributing 36 point sources around a spherical diffuser, each light source is located at the vertex of a one-frequency icosahedron.


Descriptors :   *LIGHT SOURCES , *SAMPLERS , *PHOTOMETRY , FREQUENCY , MEASUREMENT , DETECTION , COMPUTERS , SHAPE , INSPECTION , EXTRACTION , VISION , DIFFUSERS , ROUGHNESS , REFLECTANCE , COMPUTER VISION , SAMPLING , LIGHT , ILLUMINATION , REFLECTION , SURFACES , THREE DIMENSIONAL


Subject Categories : Photography
      Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE