Dual Base States Model With Amendments Based On Event And Version Management

Spatio-temporal model is the core of temporal GIS. Real-time database updating, low-redundant data storage and high efficiency spatio-temporal information retrieval are being the hotspots in the domain of spatio-temporal model. During the research of spatio-temporal model, the proposal and improvements of base state with amendments model greatly enrich the research in the domain, and promote the development of the model. The paper which is based on the technical characteristics of the base state model with amendments and combines with actual demands of geographic spatio-temporal data storage and spatio-temporal data operation, intends to improve the model from organization of spatio-temporal data incremental updating and methods of history spatio-temporal operation. The main contents are as following:Firstly, the geographic spatio-temporal object is in the state of discrete and dynamical changing. The real-time updating of spatio-temporal database is of great significance for guaranteeing its currency. The improved model employs Event as an organization unit to map the change collection of real geography world into the database, drives the incremental updating of spatio-temporal data and organizes longitudinal historical spatio-temporal data to reduce the redundancy of historical data storage. Meanwhile, the model marks the geographical object life cycle with event timestamp and records its historical evolution process.Secondly, in order to consider both high efficiency of spatio-temporal data operation and low temporal redundancy of data storage, the paper proposes the storage pattern of Dual Base State to manage the database. One is Initial Base State, which is the most original state. It is the logical snapshot of the history state of the database and is the calculation foundation of the history spatio-temporal operation. The other is Base State, which is the most current state. It records the current state of the database and is in the state of dynamical updating. Between dual base states, we propose event negative increment to amend negatively base state and record incremental updating process of the database. By quotation of the conpcept of version management from DataBase, we employ version with amendments to create multiple logical snapshot dynamically between dual base states, record the positive amendments of the initial base state, so as to achieve fast spatio-temporal positioning and data reduction.Thirdly, in the improved model, we define Event Topology to maintain the spatial relationships between events upon the topological relationships between geography objects, then we construct the logical snapshot of the database, that is version with amendments. The combination of above contributes to accomplish the spatio-temporal database incremental updating, historical spatio-temporal retrieval, incremental rollback, etc.Finally, based on the research, we apply the improved dual base state model with amendments to County Land Use Current Data Management System in Zhejiang Province. We test the data incremental updating, spatio-temporal data evolution management and historical spatio-temporal operations by the System. And we verify the feasibility and superiority of the model in database current updating, history data storage and spatio-temporal data operations.