Design And Implementation Of Virtual City Oriented Three-dimensional Spatial Data Engine

Spatial information is of complex relationships, unstructured, data volume, multi-scale, time-varying and many other features. To translate and share mass spatial data in an efficient way becomes more and more important to many relative research areas. With the development of virtual reality (VR) and geographic information system (GIS), virtual city oriented massive three-dimensional (3D) spatial data has been wildly used in urban planning, simulation training, emergency command, intelligent information systems and put forward higher requirement to the performance of spatial data scheduling and storage.The dissertation takes the key technology of the virtual city oriented index and high efficiency scheduling for 3D spatial data as the main research topic and aims to build an effective spatial data engine for massive spatial data processing. The main research contents of this dissertation focuses on preprocessing method and efficiency I/O model for virtual city oriented massive spatial data. By design and implement a new Cell-Rtree index methods, spatial query could be finished in an efficient way under virtual city application environment. We also implemented a new out-of-core processes model and make research on asynchronous I/O acceleration method for spatial data exchanging and scheduling. Based on the research results, a virtual city oriented VR-GIS spatial data engine were developed and integrated. The main contents and results of the research in this dissertation are summarized as follows:(1) The design of a new Cell-Rtree method for Virtual City oriented 3D spatial data preprocessing and indexing.By analyzing the features of virtual city oriented 3D spatial data, we proposed a new Cell-R Tree index structure which has better time complexity and less overlapping in virtual city applications and optimized 3D spatial data storage structure through Hilbert curve. (2) The out-of-core service model for virtual city oriented data swapping based on IOCPThis paper implemented an asynchronous method to load and make real-time scheduling on hundreds GB level spatial data using out-of-core technology and IOCP distribution mechanisms which solves the massive spatial data overload problem in virtual city oriented platform.(3) System-Level performance optimization methodology for spatial data engineTo resolve performance bottleneck in spatial data random access and concurrent query the dissertation analyzed system performance parameters and introduced some new technologies to improve system performance includes thread pool, memory pool, I/O request management, etc.(4) The integration and development of virtual city oriented 3D rendering engine and spatial data engine.The dissertation realized the integration of the virtual city oriented spatial data engine and virtual reality 3D rendering engine. Based on the efficient indexing and scheduling ability which provided by spatial data engine, the dissertation implemented dynamic integration between spatial data engine and virtual city application which breaks out the data carrying capacity and performance capacity limits in the conventional 3D rendering engine which applied in virtual city-level applications.