Plane-based self-calibration and improvement of three-dimensional multi-beam laser scanning with two-axis-mirror

The geometry and calibration of three-dimensional multi-beam laser scanning (MBLS) is more difficult than single-beam laser scanning, especially for a one laser emitter and multiple laser-echo detection within the same optical path and scanning with a two-axis-mirror. This paper focuses on the influence of the main systematic errors upon the geometric imagery of the MBLS, and presents a plane-based self-calibration method to improve the geometric positioning. First, the model for geometric imaging and systematic errors for the MBLS is presented, and the adjustment of the plane-based self-calibration is developed. Second, the influence of systematic errors upon geometric imagery of the MBLS is simulated and conducted to find the main errors. Third, a strong network configuration based on planar calibration is addressed and implemented, and the improvement of accuracy is examined via qualitative and quantitative analysis. The results show that the rangefinder offset, horizontal direction circle index and vertical circle index are the main systematic errors. The accuracy of distance is corrected from 29.94 cm to 2.86 cm with an improvement of 86.89% for the plane-based calibration, and validation indicates that this is corrected from 25.47 cm to 5.60 cm with an improvement of 88.25%.