Development and Calibration of a Gonio-Spectral Imaging System for Measuring Surface Reflection

  • Authors:

  • Akira Kimachi;Norihiro Tanaka;Shoji Tominaga

  • Affiliations:

  • The authors are with the Department of Engineering Informatics, Faculty of Information and Communication Engineering, Osaka Electro-Communication University, Neyagawa-shi, 572--8530 Japan. E-mail: ...;The author is with the Department of Industry-Information Science, Faculty of Social Sciences, Nagano University, Ueda-shi, 386--1298 Japan.;The authors are with the Department of Engineering Informatics, Faculty of Information and Communication Engineering, Osaka Electro-Communication University, Neyagawa-shi, 572--8530 Japan. E-mail: ...

  • Venue:
  • IEICE - Transactions on Information and Systems
  • Year:
  • 2006

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Abstract

This paper proposes a gonio-spectral imaging system for measuring light reflection on an object surface by using two robot arms, a multi-band lighting system, and a monochrome digital camera. It allows four degrees of freedom in incident and viewing angles necessary for full parametrization of a reflection model function. Spectral images captured for various incident and viewing angles are warped as if they were all captured from the same viewing direction. The intensity of reflected light is thus recorded in a normalized image form for any incident and viewing directions. The normalized images are used to estimate reflection model parameters at each surface point. To ensure point-wise reflection modeling, a calibration method is also proposed based on a geometrical model of the robot arms and camera. The proposed system can deal with objects with surface texture. Experiments are done on system calibration, reflection model, and spectral estimation. The results using colored objects show the feasibility of the proposed imaging system.