Goniophotometric System for Measuring Object Surface Reflection Using Robot Arms.

Abstract

n-tanaka @ nagano.ac.jp This paper proposes a goniophotometric system for measuring light reflection on an object surface using two commercialrobot arms and a digitalcamera.It a lows four degrees of freedom in incident and viewing angles necessary for fulparametrization of a reflection model. Co lectedimages are transformedas if they were a lcaptured from the same viewing direction.A database of measured surface reflection is then constructed directly from the pixelvalues of the transformedimages at each individualpoint on the object surface for a whole set of incident and viewing angles.From the co lected image database,the parameters for the Torrance-Sparrow surface reflection model,such as diffuse reflectance,specular reflectance and surface roughness,are estimated.The proposed system enables two-dimensional pixel-wise measurement and modeling of surface reflectance,and thus,can dealwith objects with spatia ly nonuniform surface reflectance.Experiments were performedon colored polyvinylchloride sheets.The estimatedTorrance-sparrow reflection models showedgoodagreement with the measurement data obtainedby the proposedsystem.