Car Laser Point Cloud Data With Quasi-dimensional Modeling Study

With the development of geo-spatial information science and geo-spatial information industry, the fast obtain and automatic processing technology is the core of three-dimensional space and is the development frontier of Geo-spatial information processing technologies. The laser scanning measurement technique can directly obtain the high-precision three-dimensional information, and it is an important complement of traditional measurement techniques, at the same time, high-precision positioning an attitude determination products are gradually civilianization, these new techniques have greatly accelerated the development of high-precision mobile mapping system, In comparison, airborne laser scanning measurement system has been technically more mature , ground fixed laser scanning measurement system also has a larger progress on research and development , but the study of vehicle laser measuring system and the treatment of laser scanning data is lagging behind , Based on this, the article make a related research and implementation on registration of vehicle laser-point cloud data as well as three-dimensional modeling and visualization .After introduced the'Vehicle Multi-sensor Fusion System'which developed by CNU project team, the article made a detailed exposition on vehicle laser-point cloud data registration which including time registration and space registration , time registration mainly uses a unified GPS time system which is realized mainly by means of a combination of hardware and software; space registration mainly introduces some coordinate system used by multi-sensor fusion system and mutual conversion between these coordinate systems , Finally by using of the position and attitude data provided by GPS and IMU, through three-dimensional coordinate transformation model , to make the data which is in Cartesian coordinate system switch to the projector coordinate system , at the same time, design and prepare procedures to complete the whole registration process , at last, to make a accuracy assessment on system and registration method by experiment. After getting the accurate vehicle laser-point cloud data, this article further studied the pre-processing of vehicle laser-point cloud data and three-dimensional modeling. Data preprocessing mainly introduced preprocessing method of semi-automatic data and automatic data , automated data pre-processing methods is mainly on the research and implementation on point cloud data filtering classification, the algorithm through mathematical morphology approach to make car laser-point cloud data into ground points and non-ground points , at the same time give the algorithm flow chart and implementation , and then constructing irregular triangulated network (TIN)on the ground point at the time of three-dimensional modeling and modeling with related software on non-ground points ; At last, through introducing the VC + OpenGL programming, the article made the well-built model visualized and the roaming of scene.The article finally summed up the advantages and the problems of this system and prospects the development prospects of mobile mapping system and research directions of vehicle laser-point cloud data processing and modeling...