基于畸变规律的三维结构光测量系统标定

Calibration of 3DStructured Light Measurement System Based on the Properties of Lens Distortion

标定是结构光三维立体视觉测量系统中的关键一步,标定的准确性对测量系统至关重要。基于镜头的畸变规律,提出了一种新型的系统标定方法,即以光轴为中心分隔同心圆环,形成多个子标定区域,通过反向投影标定法一一进行标定。此法充分考虑到了大视场和透镜光学单元畸变不一的影响,提高了局部和全局标定精度。实验结果表明,在扩大视场约为1050mm×750mm时,分为两区域的投影仪标定精度提高了72.8%,系统测量精度达到28.9μm,展示了对畸变更好的处理效果。该方法不依赖任何特殊的标定设备,操作简单,准确易行,可同时满足大视场和高精度的测量要求,并增强了系统实时性。

Calibration is an important process in 3D vision measurement for the structured light system. The calibration results influence measurement accuracy. After studying the properties of lens distortion, a new calibration method is proposed in which the target region is divided into many sub-regions of concentric rings formed by treating the optical axis as a center point along with a given radius. Then, according to the reprojection method, calibrations are done one by one. Since this method takes the impact of large filed of view as well as lens distortion into account, calibration accuracies of both local and global regions are improved dramatically. The experimental results show that to the field of about 1050 mm×750 mm divided into two regions, the accuracy for projector calibration increases by 72.8% and the system precision reaches 28.9 μm, which indicate the advantage of this method on distortion processing. The method does not rely on any special calibration equipment, and operates easily and conveniently with good accuracy. It is proved that the proposed method can meet measurement requirements of large field, high precision, and be more compatible to real-time system.