The analysis of surface texture using photometric stereo acquisition and gradient space domain mapping

摘要

A novel machine vision based inspection technique was developed for the analysis of three-dimensional (3D) surface textural patterns. Previous machine vision based methods of texture analysis have in general analysed projected two-dimensional (2D) textural patterns. This paper presents an innovative approach for the direct analysis of 3D texture topography. The method employed has particular application for the evaluation of textures frequently encountered during numerous manufacturing and finishing processes. A 3D surface topographic description is acquired using a photometric stereo technique. A method of gradient space domain mapping and surface reconstruction are used to characterise textural form, shape and regularity, and to quantify any observed deviation in an idealised form in relation to a CAD based prototypical texture model. Unlike conventional viewer centred methods for the assessment of projected texture, the technique offers a 3D object centred analysis, uses a fixed lighting configuration, is largely insensitive to a variation in object pose, and is rapid in operation. These aspects are of considerable advantage in terms of practical application. The technique was applied to real texture samples, and a selection of experimental results are presented in this paper.