Research On Calibration Of The Multi-line Laser Scanner

The multi-line laser scanner can achieve “No-contact” to obtain high-precision 3d information of objects,which has a series of characteristics and advantages such as small size,360° scanning,high efficiency and so on.In recent years,it has been widely used and concerned in the field of surveying and mapping.As the core part of mobile measurement system,the multi-line laser scanner is the main acquisition equipment for obtaining high-resolution 3d spatial and geographic information data.However,during the process of the actual data collection,the scanner will be affected by various external factors and and exists errors,so its precision is related to the quality of point cloud data.Aiming at the problem that the multi-line laser scanner cannot meet the demand of high precision measurement in the field of surveying and mapping because of the existence of errors,the calibration of the multi-line laser scanner is studied in this paper,which provides a reliable basis for evaluating the performance of the scanner and the quality of the collected data.The main research and contributions are as follows:(1)Aiming at the main error sources and classification methods of the multi-line laser scanner.The theoretical derivation and analysis are carried out for the point position median error and the systematic error model.What’s more,the scanner error analysis of simulation is carried out with the prototype of VLP-16,the concrete content includes the random of range error,the random of angle error,the system of range error,and the system of angle error on the quality of the scanner to measure data,from the perspective of qualitative analysis and quantitative analysis.At last,the influence of the performance error parameters on the measurement accuracy of the scanner and the corresponding processing methods are studied.(2)Aiming at the internal parameter calibration methods of the multi-line laser scanner.In this paper,the mathematical model of the static self-calibration of the multiline laser scanner and the correlation between the error parameters are analyzed.In addition,the methods of the nonlinear least square based on planar constraints selfcalibration and the nonlinear least square based on cylindrical constraints selfcalibration are applied to the laser scanner calibration work.This paper proposes a method of the combination of plane and cylinder nonlinear least squares self-calibration,and carry out the calibration simulation experiment and the measured experiment as the example of VLP-16.At last,the effects of the three algorithms calibration methods are compared and analyzed.(3)Aiming at the external parameter calibration method of the multi-line laser scanner and the camera system.The calibration method of camera internal parameters is studied by taking digital camera AS100 as an example.On the basis of the calibration results of the multi-line laser scanner and the camera internal parameters,the external parameters of the measurement system composed of the multi-line laser scanner and the camera are calibrated,and the accuracy of external parameters calibration results is evaluated.