The Research On 3D Measurement Of Free Form Surface Based On Computer Vision Technique

With the development of CAD and Computer Graphics, Reverse Engineering is becoming a relative independent subject in CAD/CAM, which is stemmed from advanced manufacturing technology. It is possible to products' shape modification design and rapid market response, which can compact the time from design to manufacturing and improve the competition on market.In this paper, one of the key techniques of reverse engineering, 3D measurement method of free form surface, is studied. Based on a prototype platform of 3D object measurement, the software package is designed on the basis of light-cut measurement theory of computer vision. The set-up of pinhole model of the camera, the once and twice calibration of the sensor and the real time image collection and processing are described. Using the parallel thinning and horizontal average thinning algorithm based on the variable template in image processing, it is well solved the trade off between thinning speed and precision. Based on Screw theory, the transform array between two coordination systems is calculated to deal with the data fusion in different view angle and synthesize the 3D model of a object. Finally, the model is displayed and it can be rotated at any angle, zoomed at any scale and translated at any direction.It is showed through analysis the result data that the measurement system can achieve a rather high speed and accuracy with strong stability and flexibility, which reaches the expected target. It will promote the development of 3D measurement in our country in academic and practical.