The Research Of 3D Reconstruction And Measurement System Based On Laser Radar

Measurement is the information acquisition method and it is one of the most important parts of the machinery science. Laser radar as a measurement instrument has many merits such as monochromatic, good in coherence, strong directive and speed of light flight. These merits cause the laser radar scan technology use depth information to realize 3D reconstruction and survey more precise and convenient than traditional method. Laser radar scan technology has widely applied in great size object on-line rapid scanning and other industry measurement and localization fields. However, how to enhances the system measuring accuracy of 3D reconstruction and measurement of the great size object as well as data processing speed become the new task which is urgent to be solved.This article has designed a 3D reconstruction and measurement system based on the LMS291-S05 2D scanning laser radar. Build the laser radar movement platform and realizes the 2D scanning laser radar to 3D scanning measurement. The data transmission connection between the laser radar and the PC is established. Detailed error analysis on the system is processed and the influence that system error and random error to the measurement result is researched. Also an improved 2D median filter algorithm is used for the scanning data pre-processing. Finally the different 3D coordinate’s data matching method in the multi-angles of view situation is discussed. Then the triangle grid reconstruction method is used to construct the object superficial outline. The innovative research contents and the main achievements of this thesis can be concluded as follows:1. Based on the analysis of 3D scanning principle, a new scanning system structure is proposed, which is used 2D scanning laser radar, servo motor and motion control card to realize the 3D scanning. This system structure can reduce the system’s overall cost and realize the same function of traditional 3D scanning system. It is very helpful for the economic application in the engineering practice of the Laser Radar Scanning Technology.2. Through the theoretical analysis and the experimental studying, the main error sources are analyzed and the error transformation mathematical model of the 3D reconstruction system is carried out. The system main error influence factors include: the angle error of the structure installation, the scanning center distance error of the structure installation and laser radar survey distance error. The error transformation formula has been deduced from the carefully analysis of the above error influence factors. Hence the system error and random error influence on the final measurement result is given. Moreover a Two-stage least squares method to compute the system error and the corresponding software error compensation method of the measuring data to increase the measuring accuracy are proposed. Meanwhile the variation characters of random errors in the X, Y and Z direction along with the change of distance error of distance measurement and servo motor angular positioning error have been carefully analyzed.3. This paper used the idea of 2D image filter algorithm for the pre-process of scanning data. Noise can be reduced by using the improved median filter algorithm. Experiment results show that the data process speed and effect of the filter have been improved significantly.The experimental study has already obtained the preliminary success. The research and experiment results proved that the 3D reconstruction and measurement system proposed in this thesis which is based on laser radar scanning can realize the rapid scanning, the digitized reconstruction and the measurement. The partial research result has already applied in the chassis positioning system based on laser radar scanning in the Waigaoqiao Container Terminal of Shanghai Port.