Research On 3D Measurement Technology Based On Surface Structure Light Stereo Vision

The three-dimensional measurement technology which based on structured light has a wide application prospect in the modern industrial production due to its high measurement speed and high precision.This topic mainly focuses on the measurement of Beethoven's plaster heads.Based on computer,mechanical,image processing,and optical techniques,this paper has conducted in-depth research and exploration on the hot and difficult issues in the three-dimensional measurement of structured light.Phase decoding method research and analysis.First,the traditional phase extraction method is introduced.In the unwrapping phase of the parcel phase,the traditional method of unwrapping the parcel phase obtained by the four-step phase-shifting method will produce a “pull line” effect.The use of Gray code encoding plus phase shift method and multi-frequency heterodyne method avoids the related problems.Through the experimental comparison and analysis of these two methods,the multi-frequency heterodyne method is selected as the phase decoding algorithm of the subject.Phase decoding method error analysis and algorithm optimization.Due to the influence of the experimental equipment and the environment and the imperfect algorithm,we could not obtain the ideal phase map in the experiment,and there would be a phase "jump" phenomenon.Through in-depth analysis of the phase error,the design frequency of the grating stripe is adjusted accordingly.In order to eliminate the influence of the gamma nonlinearity of the projector,the minimum phase change method is used to compensate the package phase.System calibration.In order to perform 3D point cloud reconstruction on the measured object,the system needs to be calibrated.In the calibration of the camera,the camera's internal reference matrix was acquired based on Zhang Zhengyou's camera calibration principle and Open CV.In the calibration of the projector,the difficulty is mainly focused on how to make the projector “catch” the image.Further improvements are made in Zhang Song's calibration method,and a four-step phase shift method is used to directly obtain the board.The true phase value at the corner point,and convert it to the corresponding physical coordinates,is the "captured" image for our projector.The calibration of the measurement system was completed on the basis of the final reference matrix.3D point cloud reconstruction.According to the massive three-dimensional point cloud data obtained in the experiment,a series of processing processes such as point cloud preprocessing,topological relationship establishment,triangulation and surface fitting,etc.,finally restores the 3D point cloud outline of the measured object.