3D Shape Measurement Based On Structured Light

As the development of information technology, optical3D measurement receives wide attention and plays an increasingly important role in enormous fields including automatic detection, automotive industrial design, biomedical, virtual reality and security etc. Structured-light3D shape measurement, with the features of non-contact, non-lossy, audience scanning and high accuracy, has been developing rapidly and researching widely. In this paper, we mainly select Fourier Transform Profilometry and Phase Shift Method as the theory of three-dimensional shape measurement.Now3D shape measurements are mostly based on PC systems, embedded shape measurement is not yet mature. The3D shape measurement contains a large number of phase solving and phase unwrapping operating, which is not conducive to the rapid measurement on a general computer. Then this paper proposes the corresponding improvements, the main work is as follows:(1) This thesis designed and implemented3D shape measurement system with FPGA and DSP, including the stripes design generation, stripes output projection, image acquisition and data processing module. Cyclone series FPGA are used to design and achieve sinusoidal fringe coding. With DVI technology RGB image signal can be transferred to the LCoS micro projector. Because of the accurate timing in the FPGA and the well anti-jamming of DVI technology, phase fringe patterns can be accurately projected with720p micro projector. We improved stripes quality from the modulation coefficient, light intensity and Gamma effect. The DSP board using DM642core is responsible for image acquisition and data processing. By the read signal flag from the FPGA the data of the measurement area will be collected with CCD image sensor. With the operating performance of DSP, phase solving and Spatial Phase Unwrapping can be implemented rapidly in3D shape measurement.(2) We Proposed algorithm optimization based on Lookup Table for solving the arctangent calculation in the phase shift method, where improved the speed of phase solving in the cost of small space resources. With phase shift method, the experiments show that the LUT-based algorithm can effectively reduce the arctangent computation time.(3) To phase-height mapping calibration method, we propose the optimized combination of parameters to reduce measurement error, under a stable and tunable optical platform. Combine with the improvement of the stripes, in the normal measurement our experimental accuracy is0.9mm. After the specific analysis of the overall program of hardware and software based on Fourier Transform Profilometry and three-step Phase Shift Algorithm, We carried out the experimental measurements.