One Method of Plane Direction Measurement by Using of the Grating Fringe

The mapping between the three-dimension (3D) physical space parameters of the target to the two-dimension (2D) image captured by the camera system is very important in the machine vision, especially in the omni-directional vision system for mobile robots. In practice, the 2D image captured by camera includes only part of the information of the 3D target and the 2D image changes a lot along with many factors. The 2D image captured depends not only on the optical parameters of the camera system, but also on the position of the physical target location and the relative direction of the physical target. One model is described under the investment of the geometric relationship between the camera and the target in this paper. The structure light to determine the target surface normal line direction and this light used in this model is produced by an optical grating. A line CCD camera is used to measure the light intensity of the structure light and the data of the light intensity distribution is transformed into a computer with an adapter card through ISA bus interface. The quadratic fitting equation is used to smooth the measured light intensity data distribution and to determine the local maximum value of the intensity. The precision of this measurement method is higher than 10^-2. This plane direction measurement method can be used in robots vision and many other cases such as the inspection, measurement and examination of 3D profile in research, industry, security and so on.