Construction Of DEM Based On Three Dimensional Laser Point Cloud Data And NURBS Surface

Based on the rapid development of modern social economy and technology, the two-dimensional plane image has been unable to meet the people's demand of spatial information, users are more likely to pursue more intuitive and virtual 3D real scene. 3D data is the basis of 3D surface construction. With more and more commercial CAD software developed by the powerful 3D model refactoring tools, using 3D data to reconstruct the 3D real scene is no longer a luxury, and has gradually developed a vast field of application, including the field of manufacturing industry, ancient protection, medicine, geology disaster governance and so on.3D laser scanning technology is a fast, non-contact mean of surveying and mapping. It realizes the authentic and high precision 3D data acquisition of the target, and finally got the data as the 3D point cloud, which contain information including surface geometric characteristics, three-dimensional structure and texture of the target object. After a series of related processes, the point cloud which acquired by scanning can be analyzed, calculated, scenario reconstruction, planning design and further application.This paper briefly introduced the principle, classification, characteristics and application fields of 3D laser scanning system, and summarized the processing of 3D laser scanning point cloud data by procedure, explained the common part of the point cloud data processing methods in detail. After that, the basic concepts of the NURBS were briefly introduced. This paper focuses on the exploration of a regional geological disaster management project as a case, using Maptek I-Site 8820 type ground 3D laser scanner as the point cloud data collection tool. Then select a part of the point cloud through the processing software I-Site Studio which was matched with the scanner to do some pretreatment, such as stitching, filtering and compression. After that, exporting the data to a common format and using the professional 3D modeling software Geomagic Studio to reconstruct the DEM of the study area by the 3D laser point cloud and NURBS surface construction method of reconstruction. Finally, the error sources in the process of point cloud data acquisition, the accuracy of point cloud and the quality of the model are analyzed and evaluated. The result shows that the precision of the DEM, which reconstructed by the 3D point cloud data and NURBS surface can meet the users' requirements, and the model of the DEM constructed by NURBS surface is not only high in continuity on the surface, but also easy to operate. Such features are of great importance in monitoring and analyzing the surface deformation of landslide, and predicting the range of possible influence of geological hazards.