Three-dimensional shape measurement of complex surfaces based on optimized dithering fringe patterns

Journal of the European Optical Society-Rapid Publications

Chengdong Wu¹  Feng Lu¹  Jikun Yang² 

[1] Faculty of Robot Science and Engineering, Northeastern University;Ophthalmology, General Hospital of Shenyang Military Region;

关键词: Fringe analysis;    Binary defocusing;    Dithering;    Optimization;   

DOI  :  10.1186/s41476-018-0094-8

来源: DOAJ

【 摘 要 】

Abstract Background Optimized dithering fringe pattern is a promising method for high-speed, high-accuracy three-dimensional shape measurement. The recently proposed dithering optimization technology optimizes the fringe quality in either phase domain or intensity domain according to their objective functions. Phase-based optimization is direct and effective, but it is sensitive to projector defocusing levels. Intensity-based optimization is robust to projector defocusing levels, but it does not fully improve the phase quality. In practice, it is difficult to control defocusing levels so it is still a challenge to get high quality fringe patterns which affects the measurement quality under different defocusing levels. Methods In order to get high-quality binary dithered patterns which are robust to defocusing levels, this paper proposes a weight object function. This function combines two parts: a global intensity part and a local structure part. The global intensity measurement is based on the normalized mean squared error. The local structure measurement is based on residual error of intensity. To generate high quality fringe patterns, the weight object function is applied to the best patch framework. Results and discussion Both simulation and experimental results demonstrate that the phase-based optimization method and the proposed method perform better than the intensity-based optimization method under nearly focused. However the quality of measurement results from phase-based optimization will decrease with the defoucsing levels increasing. The proposed method is robust to the defocusing levels and it can still reduce the phase error when the projector is strongly defocused. Conclusions The proposed method can get high-quality binary dithered patterns under different defocusing levels by combining global similarity and local residual error of intensity. It inherits the merits of binary fringe pattern so that gamma calibration of projector is not required. In practice, the proposed method can be used to generate high quality fringe patterns. The experiment results verify that the proposed method can get better measurement results without considering the projector defocusing levels.

【 授权许可】

Unknown