A simple calibration method for structured light-based 3D profile measurement

Structured light is commonly applied to various 3D surface profile measurements because of its nature of low cost and high speed. The existing structured light-based reconstruction model and calibration can be classified as analytical and empirical methods, among which the empirical methods are often used since it is pixel-wise method. However, the existing empirical matching difference-height models are oversimplified and the empirical calibration methods are cumbersome and time-consuming. Therefore, two contributions of this paper are: first, we derive a general matching difference-height model with high consistence and resolution, the proposed model is independent of hardware configuration; second, a multi-sphere calibration strategy is proposed to simplify and accelerate the calibration procedure by a flat board with four balls. Some experiments are carried out to evaluate the proposed methods. The experimental results demonstrate that matching difference-height model improves the resolution and consistency by 3% and 13% in comparison with the traditional models; while, the proposed calibration duration is reduced to 27% of the conventional plane-translation calibration method.