Line Structured Light Measurement Of Abrupt Curvature Surface Profile

Since the coming of optical 3D profile in 80 s,a lot of researches have been devoted.With the development of computer,laser and image processing technologies,there are some relative mature measurement methods in optical 3D profile which occupies a large proportion in the field of 3D measurement.This optical profilometry is now widely used in the fields of 3D measurement.The technological feature of the optical profile is quite different from the traditional measurement methods,which has the advantages of non-contact,nondestructive,real time and so on.The existing measurement techniques can't meet the requirements of complex contour measurement,especially an object with sharp curvature of a surface.To solve the sharp curvature problems,a binocular vision measurement system based on line structured light in three light sources has been proposed in this thesis.In this thesis,the measurement system mainly has completed the measurement of the curvature of the objects.The main work of this thesis includes the following aspects:1.Based on the existing line structured light measurement equipment,the contour measurement system has been designed,and the surface profile measurement of the abrupt change of curvature has been carried out.2.The principle of line structured light method has been briefly introduced,and several key technologies to be used in the measurement system have been studied emphatically,such as camera calibration technology,which is necessary to correct the image in the measurement system and eliminate the distortion,and laser lock-in imaging used to filter out the interference light and reduce the disturbance to the measured profile.Three dimensional contour reconstruction techniques have been used to reconstruct the full 3D contour model of the measured object.Among them,three kinds of classic 3D reconstruction algorithm have been introduced.The thesis has analyzed the advantages and disadvantages of these algorithms,combined with the actual characteristics of the measurement system,and the reconstruction of selected splicing method with parallel contour of 3D contour of the object.3.The image algorithm used in the measurement system has been studied carefully.This thesis has compared the image preprocessing method and stripe center extraction method,and the method suitable for this thesis has been selected.In order to improve the measurement accuracy of the system,a new algorithm based on NURBS has been proposed.In addition,this thesis has made a special study on the judgment and processing of the special contour,which can effectively measure the abrupt change of curvature.4.The measurement system has been built,and the software has been compiled and debugged.Three kinds of objects with abrupt change of curvature have been measured,and the results of the measurement system have been analyzed and summarized.