A new approach to high precision 3-D measuring system

A 3-D measuring system is important in many industrial applications like object modeling, medical diagnosis, CAD/CAM, multi-media, and virtual reality systems. However, it takes a lot of effort and cost to develop a high precision 3-D measuring system. A novel approach is introduced in this paper, with a view to develop a 3-D measuring system to meet the requirements of high performance through low cost equipment. A laser projector with controllable light intensity and phase is designed and used as the active light source. When the light is projected on an object, the varying depths of the object surface cause phase variations in the active light projected. These phase changes are used to find out the surface coordinates of the test object using simple Digital Signal Processing techniques. The advantages of the proposed method include the following: (1) as the measuring speed is fast, our method is suitable for on-line 3-D applications, e.g. the monitoring of human body or on-line detection; (2) only a single image is required to obtain the necessary phases, so the vibration errors can be avoided; (3) each CCD element is taken as a sample point, thus a high resolution result can be obtained; and (4) the measuring result is accurate. The experimental results reveal the superiority of the proposed method.