Zhengping Weng

3D GIS database model for efficient management of large scale underground spatial data

One issue of GIS is management of huge amount of spatial data. Nowadays, acquisition capacity of 3D spatial data with various scales and resolutions is much more convenient due to new 3D acquisition technologies. It is a difficulty that how to efficiently and synthetically organize and manage large scale underground 3D spatial data with contents of continuous distribution and nonuniformity. A 3D GIS data management system framework with three layers is proposed to deal with large scale underground data integrated management. The related key issues and methods include: (1) Multi-scale underground spatial object concept model. (2) 3D spatial database model considering spatial and semantic relationship and corresponding data structure is introduced to support extendable storage environment such as file system, typical commercial database management system and cluster parallel system. (3) True 3D spatial index considering Level Of Detail (LOD). (4) Efficient dynamic dispatch method of great amount of 3D spatial data is adopted based on 3D data content and associated information. (5) 3D Spatial Data Engine (SDE) provides a uniform access interface for file management system, relational database management system and cluster parallel system and other applications. The 3D GIS database model focuses on the key issues of massive underground 3D spatial data provides a new way for the high performance database organization and management of true 3D geological data as well as its integration with the aboveground spatial data.

Design and implementation of log management module in three-dimensional spatial database management system

Log management module plays an important role in the massive spatial database management system. Recently there are few three-dimensional spatial database management systems with pertinent log management sub-system, or the administrator can only use the log, which is attached by database system, to recover the data. To improve this issue, hierarchical structure of the log management module should be taken into account. The overall design of three-dimensional spatial database management system is as follows: three-dimensional spatial database (including database system, file system), three-dimensional spatial data engine, and three-dimensional space management tools. The log management module is designed to solve the problem of complexity and inconvenience of three-dimensional spatial data manipulation records. According to the 3D spatial database management system design, we divided the log management into three layers. The log management system includes monitor layer of three-dimensional spatial databases triggers and file database system operations recording statements, interface layer of log management module of three-dimensional spatial database engine, and graphical user interface layer of log management module of three-dimensional spatial data management tools. Monitor layer design includes database system trigger design. When the database table has been dynamically created, the trigger will be automatically created and record the database operations, then the file system calls function to record the log. Interface layer design includes accessing the database, reading the log table in database and other integrated operations, including query and delete. Graphical user interface layer mainly includes the design of graphical interfaces, the function call form interface layer, and log data operations. In order to work on the layers conveniently, database system trigger and file database systems record are used to record the operation of the database. The log module interface in three-dimensional spatial data engine is used to exchange the data between graphical interface and underlying database. The log module in database management tools can directly provide a graphical interface, but not need to provide access functions to get the log data. This design method has an excellent scalability and flexibility, and can also be made appropriate changes to meet the new needs.

Three-dimensional spatial indexing method of complicated geological scene

How to create high-performance true three-dimensional spatial index for the complicated geological scene to ensure the effective storage management and dispatching of the TB-class mass complicated geological scene data is one of the key technical issues of the 3DGIS, which needs to be resolved urgently. The inefficient space division and the high rate of index node overlap problems will appear in the continuous nonhomogeneous geological space by using the existing three-dimensional R-tree series spatial indexes. They cannot effectively deal with large-scale complicated geological scene data. In order to resolve these problems, the amount of data evaluating techniques of geology solid and multi-levels indices techniques are the introduction of three-dimensional spatial index. Used three-dimensional space division technology based on the amount of data evaluating technology of geology solid, combined with three-dimensional spatial clustering, spatial scan sorting, fast convex hull algorithm and CSR-Tree packing construction techniques, the multi-level mixed three-dimensional spatial index can be constructed dynamically. It advances the query efficiency by using the topological relationships between the geology solids, realizes the complex geological data management and efficient dispatching, and affords new ideas and new method for the continuous nonhomogeneous three-dimensional space.

Multilevel updating method of three-dimensional spatial database

Spatial entities and the relationships between them in real world are changing over time, and the demands from continuous updating of all kinds of data are improving constantly. Therefore, how to maintain the current trend of spatial database becomes increasingly important. However, the spatial data, which exhibit the further feature of massive data, multilevel, concurrent operation of multi-users, make the data updating more difficult which is reflected on inefficiency, insecurity and inconsistency, etc. According to the features of spatial data and problems on updating of spatial database, the multilevel updating method of three-dimensional spatial database is presented based on the systematic analysis of theory and technology of Spatial Data Engine(SDE). In our system, the three-dimensional SDE introduce the SDO_GEOMETRY, which is an abstract data type provided by Oracle Spatial, to store spatial data types. The OCCI (Oracle C++ Calling Interface) is also introduced instead of ODBC or JDBC to access and update the spatial data to improve the efficiency and connection stability of the database system. The multilevel structure of spatial data shows its feature of un-structuring, structuring and object-oriented during the storage of database. Finally, the multilevel spatial data updating method, which is realized in modules of Three-dimensional Spatial Data Management System to schedule and update the massive three-dimensional spatial data, improves the efficiency, interaction and integrity of spatial database.