Three dimensional measurement based on image shift and its applications in object inspection

A novel three-dimensional measurement method is proposed in this paper based on images shifted to a preset position. The proposed measuring system with a simple architecture can be easily established with very low installation costs as long as two images shifted by a certain window frame can be obtained. To show the effectiveness of the proposed approach, an object inspection system for use in a production line based on the measuring method is demonstrated in this paper, where a single CCD camera is used to capture images with the help of two position sensors to obtain non-contact 3-dimensional measurements for objects on a conveyer. Because a single scan line of images is only used for calculating the measurements including distance from the object and length and width of the object under inspection, the proposed measuring method has demonstrated itself as an efficient yet cost-effective method in achieving the objectives of sorting or screening defects of objects. Simulation results show that average measurement errors generally lie within a satisfactory range of 1.38%.