External parameter calibration of widely distributed vision sensors with non-overlapping fields of view

In this paper, an external parameter calibration method for multiple vision sensors (MVS) with non-overlapping fields-of-view (FOV) using spot laser is presented. The main procedures of the method are as follows: Spot laser projects laser beam across the FOVs of multiple vision sensors, the spot laser is placed at least two times. At each spot laser position, the planar target intercepts the laser beam at least two times in the FOV of each vision sensor, and the 3D coordinates of the laser spots projected on the planar target are reconstructed. The coordinate transformation from each vision sensor to global coordinate frame (GCF) is computed according to the co-linearity of the laser spots at each spot laser position. The proposed method connects the non-overlapping MVS by the laser beam projected by spot laser. It does not require any complex equipment, but one spot laser and one planar target. The experiment shows that when the working distance of the cameras is about 500 mm–1100 mm and field-of-view is around 500 mm×400 mm, the point pair distance RMS error of the calibrated measurement system is about 1.2 mm with respect to 1.1 m measurement range.

► The method only requires a spot laser and a planar target.
► The method only requires a spot laser to be placed at a few (at least two) different positions.
► In the real data experiment, the relative calibration accuracy is around 1‰.