Research On 3D Imaging Method Based On Solid Color LED Structured Light

With the rapid development of computer vision,3D imaging technology has been widely used in the fields of industrial inspection,health care,security protection,virtual reality and 3D printing.The 3D imaging device,studied in the thesis,is to inspect the appearance quality of the tiny cylindrical pellets.3D imaging device uses a combination of solid color LED line structured light and area array camera to scan the appearance of the cylindrical pellets.The cylindrical pellets is driven to rotate by the double-drum device.Moreover,the cylindrical pellets is driven to move at a uniform speed,and the structured light image of the end surface of the cylindrical pellets is collected by the designing of the electric sliding table device.Finally,this device processes the gotten image by the triangular distance method to reconstruct a3 D image of the cylindrical cylindrical pellets,consequently,quality inspection is achieved.The thesis mainly completed the following research contents:(1)The thesis discusses the principles which apply the triangle distance method for 3D image reconstruction deeply,and makes a detailed process deduction,the thesis effectively uses the mathematical model of the triangle distance method for3 D reconstruction.Determines the best conditions for image shooting,selects the hardware that meets the requirements,and builds 3D imaging device in the laboratory,by the imaging principle.This device uses a bi-telecentric lens and LED line structured light source which uses a peak wavelength of 520 nm to achieve accurate3 D reconstruction and simplify the design of the system.(2)The thesis calibrates the camera by comparing and analyzing the differences between the pinhole imaging model and the telecentric imaging model.According to the mathematical model of the telecentric system imaging,the relationship between the depth change and the spot offset is gotten.Unlike the pinhole system,the depth change of the telecentric system is linearly related to the spot offset,which reduces the calculation of the parameters and simplifies the process of system calibration.And then,by analyzing the image acquisition characteristics of the system and correcting the distortion from the direction parallel to the structured light,the dimension of distortion correction is reduced.(3)According to the characteristics of 3D reconstruction,the image is preprocessed to reduce the impact of image noise.The center line of LED line structured light is extracted by using the Steger method,which improves the accuracy of 3D imaging.The algorithm of constructing the light sheet in Halcon is selected to reconstruct the LED line structured light map in 3D,which can obtain the surface contour of the object.Based on the 3D imaging results,the size,Defect size,depth,and the defect ratio of cylindrical pellets are calculated,and repeated experiments are conducted to verify the feasibility of the method in this thesis.