title: Surface contouring by optical edge projection based on a continuous wavelet transform.
abstract: A novel optical edge projection method for surface contouring of an object with low reflectivity is presented. A structured light edge is projected onto a dark surface, and the image is captured by a CCD camera. The surface profile of the object is then evaluated by an active triangular projection technique, and a whole-field three-dimensional contour of the object is obtained by scanning the optical edge over the entire object surface. An edge detection method based on a continuous wavelet transform (CWT) is employed to determine the location of the optical edge. The method of optical edge detection is described, and characteristic details of gray-level distribution along the edge are analyzed. It is shown that the proposed wavelet edge detection method is not dependent on any threshold values; hence the true edge position can be determined without subjective selection. A black low-reflectivity object surface made from woven carbon fiber is measured, and the experimental results show that the profile of a woven carbon fiber can be obtained by the proposed method.
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, Singapore 1119260, Singapore. mpeqcg@nus.edu.sg
authors.forename: Chenggen
authors.initials: C
authors.lastname: Quan
authors.forename: Hong
authors.initials: H
authors.lastname: Miao
authors.forename: Yu
authors.initials: Y
authors.lastname: Fu