SURFACE TEXTURE ANALYSIS BASED UPON THE VISUALLY ACQUIRED PERTURBATION OF SURFACE NORMALS

A novel technique has been developed for the textural analysis of Lamb ertian surfaces while in the presence of a variable albedo. The method has direct application for the surface quality determination of cosme tically sensitive components, and has particular application where mor e traditional methods may prove unsatisfactory. A photometric stereo t echnique is used to facilitate the isolation of localised irregular fe atures, such as scratching, indentations or small protrusions, which m ay be obscured by a coincident, regular or random surface albedo. A ge neric lighting arrangement is employed, which obviates the need for a customised lighting configuration. This represents a significant advan tage for the configuration of industrial vision-based inspection syste ms. Promising experimental results have been obtained using example co mponents, and are presented in the paper. (C) 1997 Elsevier Science B. V.