Model Reconstruction Of Three-dimension Terrestrial Laser Scanning And The Application In Building Surveying

Three-dimension terrestrial laser scanning technology is a new measurement method in geodesy and geomatic fields. Some people called it a new revolution after the emergence of global position system. This technology uses laser to measure, can obtain a large number of three-dimensional coordinate data which is called "point cloud" data with non-contact, high speed and high accuracy. It can dynamic and truly reflect the status of objective things in real time, and provide a new technical mean for scientifically and accurately establishing digital model. With the rapid development of science technology, three-dimension terrestrial laser scanning technology is widely used in various fields. In the field of building surveying, especially the mapping of traditional Chinese architecture, it gradually replaces the traditional measurement methods. It is great significant to protect, repair building, digital and scientific manage the surveying results.This paper firstly introduced the internal and international research situations of three-dimension terrestrial laser scanning technology, summarized the technical features and applications, briefly described its basic working principle and classified the hardware equipments of the laser scanners.Then amply present the ILRIS-3D laser scanning systems and the post-processing software PolyWorks. Described the scanner's operational process in detail, and comprehensively studied the modeling method of PolyWorks against the process of dealing with scanning point cloud data, including multi-view point cloud data registration, three-dimensional geometric modeling, model holes repairing, simplifying and so on. Because the number of complex buildings'point cloud data is very huge, this paper has determined the suitable criterion of model simplifying through experiments using different accuracy.Finally applied three-dimension terrestrial laser scanning technology to the building surveying, extracted the feature lines and contours from three-dimensional model, drew the building elevations, plans, profiles and so on. Because the software can not automatically extract the contours of elevations and top views. In this paper, using plane scattered point cloud meshing algorithm to realize automatic extraction for the building's outline under orthographic projection in AutoCAD.This dissertation selected a pavilion, reconstructed its model with scanning data, and completed to draw the maps using the feature lines and contour obtained with semiautomatic extraction. The experimental results show that compared with traditional mapping, three-dimension terrestrial laser scanning technology has great advantages in the measurement's speed and accuracy, and a wide range of applications in the field of building surveying.