Research On 3D Visual Measurement System Of Monocular Structure Light

With the development of science and technology and the growing demand of people's lives,both in social life and in industrial production,two-dimensional vision has been far from being able to meet people's needs.3D vision has become a hot research topic,and the research of 3D visual measurement system based on structured light has become an important research field of computer vision.The method can not only obtain the two-dimensional information of the measured object,but also can measure the three-dimensional information of the measured object,it has a wide range of applications in the industrial detection,surveying and mapping engineering,structural measurement,architectural monuments measurement,entertainment and other fields.The three-dimensional visual measurement method of structural light does not need to directly contact the measured object,does not wear the surface of the measured object,and has the characteristics of fast speed,high precision and high practicability.It is one of the best methods to carry out three-dimensional measurement.Compared with binocular,the monocular structure of light visual measurement system has low cost,simple algorithm,large field of view and other advantages.However,the measurement accuracy and robustness of the monocular structured light three-dimensional visual measurement system are susceptible to the influence of ambient light and measurement background;and the calibration of the projector in the system has been a technical difficulty.Most of the accuracy the existing projector calibration algorithms is not high and the robustness is low.In order to solve the above problems,this paper has carried on the thorough research to the related technology,has designed a kind of monoscopic structured light three-dimensional visual measurement system.The main work content and innovation of this paper include the following aspects:First of all,according to the actual application requirements,the paper selected the right hardware,built a convenient hardware system.In order to improve the practicality of the three-dimensional visual measurement system and the human-computer interaction in the three-dimensional measurement process,the key algorithms introduced in this paper are developed,and a three-dimensional visual measurement software system is developed.Secondly,the advantages and disadvantages of various commonly used structured optical coding schemes are analyzed.Combined with the demand of measurement system and the actual measurement environment,a structured light coding scheme of Gray code plus four step phase shift is selected.At the same time,The solution of non-sinusoidal problem of sinusoidal grating in process is gave.In this paper,the decoding principle is described in detail,and the decoding process is realized.At the same time,according to the problem that the system is susceptible to the influence of ambient light and measurement background,this paper proposes a background culling algorithm based on mask image to extract the measured object from complex background,thus eliminating the influence of background environment on measurement system.The algorithm is simple and easy to operate,and is directly processed by the image taken during the structure light decoding process without increasing the additional burden on the system.Finally,the paper completes the calibration of the measurement system,including camera calibration,projector calibration and stereoscopic calibration.Aiming at the problem that the accuracy of the existing projector calibration algorithm is not high and the robustness is low,this paper designs a block homography matrix algorithm to calibrate the projector,divides the picture into multiple regions according to the corner position of the checkerboard,Respectively,for each region to obtain a single homogeneity matrix.Compared with the traditional global homogeneity matrix calibration algorithm,this algorithm can effectively overcome the influence of lens distortion and improve the accuracy of the projector calibration.The three-dimensional measurement experiment shows that the measurement system designed in this paper can perform high-precision projector calibration,which can adapt to complex measurement environment,high robustness,high reliability of measurement results,three-dimensional measurement accuracy up to micron level,and low cost hardware,with high practicality and good application prospects.