Comparison between single and dual laser pointer applications in digital scanning system

Abstract

In reverse engineering concept, points cloud becomes a very important source of information to build a digital model of a physical product. Several methods are well known in collecting points scanned from an object surface. One of them is by using a flat laser beam projected on the product surface. A digital camera is directed to the projected beam and it continuously takes digital images. This method is also called a noncontact scanning method. In our previous work a single laser pointer was applied to get a projected line (set of points) on a targeted surface. Problems appeared when two free surfaces intersecting in a sharp angle or less than about 135 degree. Product like a cube (or other rectangular part) can not be scanned successfully as it has six faces intersecting at right angles therefore some parts of the surface can not be scanned as it is hidden by the sharp corner at a certain view. This leads to an imperfect digital model developed from incomplete points cloud. To deal with this problem, a dual laser pointer system has been developed to improve the method of scanning and to enhance the quality of points cloud extracted from the scanned data. The two laser pointers are placed 90 degree to each other and the digital camera is positioned between them. The camera takes images of laser lines pointed on the object surface while the object is being rotated. Experimental results confirm a better points cloud can be developed using this new technique.