Research On Close Range 3D Measurement Technology Based On Lasear Fringes

With the development of science and technology,the process of industrialization is further promoted,and those traditional non-contact measurement methods will not be able to meet the requirements of industrialization.In the past few decades,many scholars have put forward a lot of non-contact three-dimensional measurement techniques,but the performance of these measurement methods is monotonous,and most of them are expensive.With the development of industrialization,there are more and more needs for three-dimensional measurement with simple structure,fast measurement speed and low cost.Laser three-dimensional measurement has developed rapidly in recent years.Because laser three-dimensional measurement does not need to contact the measured object in the process of measurement,it has no damage to the measured surface,so it has been widely used.In this paper,based on the triangulation method of single line laser,the calibration technology of camera is studied,and a convenient,fast and low cost laser 3D measurement system is designed.This paper analyzes the small hole imaging model of camera imaging,deduces the mathematical relationship among pixel coordinate system,image coordinate system,camera coordinate system and world coordinate system based on perspective projection model,and studies the principle of chessboard calibration of camera parameters.According to the working principle of the whole measurement system,the overall structure of the measurement system is designed,and the hardware composition of the measurement system is designed accordingly.Based on Zhang Dingyou's calibration principle of chessboard grid calibration board,the chessboard calibration board is made and the camera parameters are calibrated.The laser plane equation parameters projected by the line laser are calibrated by the least square method.After obtaining the image,the image is filtered by median filtering,mean filtering and Gaussian filtering,and it is concluded that the Gaussian filter is more effective in this paper.The results show that the threshold segmentation method can effectively distinguish the background region from the target region in the image.In the extraction of laser stripe center,a gray centroids method with fast calculation speed,high precision and simple method is selected.A single pixel centerline can be obtained by processing the image.Finally,the three-dimensional measurement system platform is built,programmed by MATLAB program,the metal devices are selected as the measurement target,the three-dimensional information of the target is obtained under the platform of the three-dimensional measurement system,and then the three-dimensional information is fitted to restore the three-dimensional appearance outline of the measured target.The three-dimensional data measured by the measurement system are compared with the real value of the target,and the effectiveness of the measurement system is verified.