Shape Measuring Of Mirror Object Based On Structured Light Method

With the development of modern industry,3D surface shape measurement has beenwidely used, meanwhile, it is put forward for higher requirements. For a kind of special andcommon glossy object, the paper proposes a new method3D surface shape measurementbased on structured light. The main difficulties to the measurement of glossy object are thespecula’s reflection of the surface will affect the image acquisition, not even gather thecorrect object information. Therefore, solving the influence of specular reflection hasimportant practical significance to glossy object.On the base of predecessors’ studies, the improved methods to the traditional Fouriertransform profilometry were presented here.1. Camera calibration is the important basis of3D information extraction from2Dimage. Camera calibration is designed to build a corresponding relationship between the3D word coordinates and the2D image coordinates. A camera calibration method based onplanar pattern is presented which is not same as the solution with other, and it isexperimented by using the MATLAB toolbox. The conclude that the camera’s internal andexternal parameter and error analysis shows that the calibration method is high precisionand easy to implement.2. The double-frequency grating Fourier transform method is improved based on theFourier transform profilometry. Therefore through the studies to the measurement principle,measurement range and error analysis, the experiment restored successfully the3D surfaceshape of the object.3. The paper analyzes the reason that the measurement of3D surface shape can’tcompletely measure the object containing reflective rough surface of the highlighted area.Then, starting from the lighting pattern of measurement system, this paper proposes amethod of measurement based on structured light which uses double-frequency sinusoidalgrating. Taking advantage of the polarizer’s and analyzer’s role respectively, it caneliminate the effect of highlights of the specular reflection on the camera system. Themethod can rebuild the mirror object and the measurement accuracy is raised three times.Theoretical analysis and experimental results prove the feasibility and effectiveness of themeasurement method.