在基于时间片的连续快照模型基础上,基于OpenGIS定义的几何类型扩充了时态类型,构建面向对象的时空数据模型,定义其抽象数据类型及相关操作;并采用对象关系数据库PostgreSQL作为实现平台,扩展其存储和查询能力。通过实例验证了上述模型及实现方法的有效性和实用性。
In recent years, spatio-temporal data modeling gain more and more attention in domain of geographical information science and database technologies. This paper expands temporal data type and completes an object-oriented form of spatio-temporal data model based on OpenGIS' s basic definition of spatial data structure. Spatio-temporal operation function and temporal relation function are also defined to accomplish operation on the data model. Moreover, definitions of relative abstract data types (ADT) are achieved as a series of temporal slices of spatial ADT,which include both data objects and functions. The ADT is implemented in both WKB (Well-Known Binary) and WKT (Well-Known Text) ways. WKBDyGeometry type can be easily stored and accessed in DBMS whereas it cannot be presented to users in a visible way. Thus, to facilitate process of intercomreunion, this paper offers EBNF definition of WKTDyGeometry, which is used to represent spatio-temporal data as an understandable string. Those data types and operations are implanted into ORDBMS-PostgreSQL to improve the storage and access capacity. In the research, primary spatio-temporal index is used to improve efficiency of querying. Some experiments are also carried out and the results come out to indicate that technologies in this paper are efficient and expedient in spatio-temporal data research fields.