Research On Phase Accurate In High-speed Three-dimensional Measurement

Optical 3D measurement has become a research hotspot in the field of computer vision.As one of the most commonly used three-dimensional optical measurement technologies,structured light has the advantages of fast speed,high accuracy,wide measuring range and wide material adaptability.Therefore,it has been widely used in manufacturing,industrial detection,medicine,human-computer interaction and other fields.With the continuous improvement of people's demand for real-time,fast 3D measurement is constantly developing.In order to make the projection speed faster,many scholars continuously reduce the number of projected fringes by coding,but these methods often reduce the accuracy of measurement.And improve the accuracy of measurement,the speed of measurement can not be guaranteed.This paper has done some research from the two aspects of improving the measurement accuracy and improving the measurement speed.The specific work and innovation points are as follows:1)An enhanced dual-frequency phase unwrapping method based on regional quantification algorithm is proposed.Firstly,the unstable fringe order is obtained by dual-frequency method,and then the fringe order is divided into regions by gray-code map.Then,the corresponding fringe order of all pixels in each region is sorted and the median value is obtained.Finally,the obtained median value is assigned to the corresponding fringe order of all pixels in the region.The quarantined fringe order is unique and stable,so the method can obtain accurate absolute phase.Simulation and experimental results demonstrate the feasibility of the proposed method.Compared with the traditional dual-frequency method and the three-frequency method,it has the measurement speed of two frequency method and the measurement accuracy of three frequency method.2)An unwrapping algorithm based on binary feature pattern matching is proposed.Different from the traditional binocular matching system,this method only needs one camera and one projector to obtain the absolute phase of the measured object.In this method,the principal phase of the standard plane,the fringe order corresponding to the principal phase and the binarization feature pattern are obtained in advance.When measuring the measured object,firstly,the principal value phase of the measured object is pre-matched with the principal value phase of the standard plane,then the binary feature pattern modulated by the measured object is precisely matched with the binary feature pattern of the standard plane,and then the unmatched points are complemented to obtain the accurate absolute phase.Experiments show the effectiveness of the proposed method.3)A 3D reconstruction measurement system based on structured light is built.The process includes the fixing of camera-projector system,the design of software,the design of grating,the calibration of system,and the reconstruction of 3D point cloud.The method presented in this paper can be used to reconstruct the measured object quickly in the system.