The Research Of Cutting Algorithm Based On3D GIS Surface Modeling

With the development and stimulation of Computer Network, Spatial Information Technique, Visualization in Scientific Computing, Parallel Computing, Grid Computing and etc., Geographic Information Science (GIS) now is undergoing the profound and prosperous change. Companied by the lengthy research of the theory and practices in3D GIS, the widely promotion of geographic information service in mobile devices and internet, the tight combination of geographic analytical functions and other applications,3D GIS has become the main focus of academic domain and the racing field of GIS companies. Spatial Analytical Function as one of the major features that differentiates GIS from other Information Systems, its problem-solving capabilities and algorithm-executing performances determine the availability and advancement of GIS platform, so does3D Spatial Analytical Function (hereinafter3D SAF) to3D GIS. Therefore, only based on the reasonable and efficient Spatial Analytical Functions, could3D GIS have the promising future.This thesis discussed the concept of3D GIS, its developing trend, platform features, application status and existing problems; studied the performance of3D GIS Spatial Analysis, emphasizing3D SAF should not only overcome the difficulties caused by3D Spatial Data Models, but also break the limits made by existing application, to create a kind of3D SAF that could handle the heterogeneous data types and different geographic objects. While3D Spatial Data Model is no more the core of current research, yet, as the fundament of3D GIS applications it affects the display mode, expression accuracy, query efficiency, and determines the design of spatial analytical algorithms and the relevant implementation. Thus, in the article it is necessary to have a proper discussion.City is the main part of the3D GIS’s fine expression and the center of3D SAF; through the incision analysis people can better understand the internal structure of artificial construction as well as the natural environment and deeply grasp the urban space for making right decisions. This research chose incision analytical algorithm in3D Surface model as research direction, focused on the deep analysis of the interior construction, semantic attributes, and structural features of the different objects in the3D space; aimed at improving the existing incision algorithms and scheming out the high efficiency cutting operation for processing the massive data model in3D scene; and solved the transformation between3D Surface Model and other data models. At last, the incising results would be expressed according to the objects’original forms. Besides, the core algorithm of surface incision analysis would be used in the model interactive fusion, so take the fusion of3D road model and3D terrain model as the example to prove the feasibility and correctness of the model fusion method.Above all, this thesis centered on the algorithm of incision analysis in3D surface model and has done much significant exploratory work. All of the algorithms and functions were embedded in the3D GIS platform "GeoScope", to realize the integrated surface incision analysis and model based seamless incising fusion. The multi-resource data detection, third-party test and project acceptance, all proved the robustness, high-efficiency and portability of this research. The research contents could be concluded to the three points as follow:(1) After the detailed description of3D GIS development process and modes, and the thoroughly discussion of3D SAF’s concept and functional classification, this thesis pay great attention to the expression of the geospatial data and the theory of3D Spatial Model. In this article, all the data models which already had were compared and their application range and development status were summarized. The integrated model (including the aboveground and underground&indoor and outdoor data) which was used throughout the research would be briefly introduced afterwards.(2) Through the deep exploration and comprehensive summery of the3D Surface Model Incision Analysis and existing algorithms, this research proposed the preprocessing algorithm based on Octree Spatial Index and OBB Collision Detection, in order to quickly find out the potential incising objects and deal with different types spatial data according to Feature Semantic Information.(3) Based on the successful implement of integrated surface incision analysis, this article also did some research on the Surface Model interactive cutting fusion. Through the fast construction of3D Terrain Model and3D Road Model, establishment of Fast Triangle Index mechanism and Data Fusion method among grids as well as other operations, it would be easy to finish Surface Model Incising Fusion and the calculation of cut&fill earthwork volume. All the algorithms are stable, efficient and reliable; it helped realize the real seamless Surface Model Incising Fusion and provide a new way to make road and terrain integrated.