Abstract
Abstract In this study, a novel 3D measurement system is developed. In this system, a CCD camera and zoom lens is used to grab object images and a stepping motor is used to rotate the object such that object image can be taken from several different directions. With the rotating device, it is able to reduce the optical limitations when reconstruct the 3D image of an asymmetric object or object with complicated shape. In this system, the technology of Shape-from-Focus is adopted to estimate the 3D geometry of examined object. Gaussian smooth filter is adopted to remove the unnecessary background noise first. The Sum-Modified-Laplacian (SML) operator is then used as an index to determine whether the surface section of the examined object is in focus or not. After the coordinates of object surface from various viewing directions are determined, the actual coordinates of the object surface are determined by the homogeneous transformation matrix (HTM). It is experimentally shown that the cone angle measured by the proposed system is quite close to that measured using a contact type 3-D coordinate measuring system. Object with complex features, such as grooves and protrusions, can also be observed with the proposed system. Key word : Shape-from-Focus, homogeneous transformation matrix.