Yoshinori Akao*1, Norimichi Tsumura*2, Toshiya Nakaguchi*2 and Yoichi Miyake*2,
3
*1 National Research Institute of Police Science
6-3-1, Kashiwanoha, Kashiwa, Chiba 277-0882, Japan
*2 Department of Information and Image Sciences, Chiba University
1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
*3 Research Center for Frontier Medical Engineering, Chiba University
1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
Japanese Journal of Forensic Science and Technology 12, 107-120 (2007)
Abstract
In this paper, we approximated gonio radiance properties of the surface
reflection component of paper sheets by BRDF model, which is required in
the digital image archive system recording the specimens of forensic document
examination. Surface reflection component was selectively acquired by measuring
the paper sheets processed with gold evaporation. Gonio radiance factor
of three kinds of gold-coated paper sheets were approximated by TSL model,
which is the linear combination of two BRDF models, Torrance-Sparrow model
and Lambert model. Relative gonio properties of each sample were well depicted
by TSL model, however a large deviation occurred in the specular reflection
geometry for glossy paper. The RMSE between the measurement and the approximation
by TSL model was under 2% of the range of measured value. The roughness
parameter in Torrance-Sparrow model corresponded with the state of surface
roughness, and also the ratio between Torrance-Sparrow model and Lambert
model showed the difference of material characteristics between samples.
Therefore TSL model was considered to be effective as a BRDF model approximating
the gonio radiance properties of surface reflected light from paper sheets.
[PDF][PDF figures](in Japanese)(to appeare)
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