Research On The Technique Of Dynamic 3d Measurement By Projecting Structured Light Based On Color Code And Model Reconstruction

3D profile measurement has been applied widely in reverse engineering, quality inspection of production, object recognition and so on, but most of the measurements are for static objects, can not measure and reconstruction the surface of objects that are moving or deforming. Dynamic 3D measurement has a good application foreground in the field of high-speed inspection, deformation analysis of object, bionics, human body measurement. This paper makes thorough research on the key techniques of dynamic 3D measurement system of structured light.Based on the principle of color code, the color information of pseudo random sequence of six hue stripes in three order is added into digital grating pattern in which intensity varies as cosine in periods, forming space code measuring sense pattern of color grating, only one pattern can realize the unique code in pixel dimension, satisfying the demand of dynamic 3D measurement. Combining phase profile measurement by projecting grating and binocular stereo vision, the dynamic 3D measurement system consisted of one projector and two cameras is established.An image decoding technique for color grating is presented, simulating the human vision process to analyse the image from whole to detail. In the intuition section phase is unwrapped by dividing the periods based on the intensity peak and the corresponding color information, in the focus section phase is demodulated by space method based on locally intensity variety. The decoding algorithm has high reliability and anti-noise ability, and the addition of rich color information effectively solves the disadvantage that traditional phase unwrapping algorithm is complex, time-consuming and can not measure the disconnected objects.The camera calibration is completed by Tsai two-step meshod and non-linear optimization using a single plane calibration block. Two projector calibration techniques are presented: one is based on projecting feature points; another is based on virtual camera idea, reversely imaging the calibration points; the problem that the three-dimensional space coordinates and two dimensional plane coordinates of import points in projector calibation are hard to achieve is solved. The experiment results show that the manipulation of calibration is easy and convenient, the accuracy of calibration is high.In order to improve the accuracy of 3D reconstruction, based on the geometrical constrain of epipolar line, the accuracy of decoding information location and match is impoved. Aim at the accuracy defect of phase coarse match, using window digital correlation technique of stereo vision by self-adaptation adjusting, achieves more accurate match in local region accordding to texture of color grating.Aim at the triangular mesh model reconstruction of discrete unorganizad point cloud of 3D measurement, a reconstruction algorithm of cycle expanding by control of appropriate triangle grow condition is presented, and a filling algorithm for large hole errors on complex surface based on curve and surface fitting is alse presented. The examples show that the algorithm can effectively reconstruct all kinds of complex point cloud and realize hole filling in good quality.The innovations are made in color code pattern design, single image decoding, projector calibration, self-adaptative correlation accurate match and triangular mesh reconstruction and repair of point cloud. The dynamic 3D measurement system has good accuracy and resolution, can realize the correct dynamic 3D measurement and model reconstruction of complex surface or disconnected objects. The research achievement expands the application range and utilization of structured light 3D measurement technique.