The design and implementation of object-oriented holistic GIS data model
面向对象整体GIS数据模型的设计与实现

Based on previous research on spatial conceptual data model of GIS, the authors present an object-oriented holistic GIS data model, and discuss data organization, data storage and access mechanism of holistic GIS system. Firstly, six features of holistic data model are introduced, and a conceptual data model is presented with a key concept, Complex Object, which is introduced in detail. Secondly, data organization means of holistic GIS are introduced. Several basic concepts such as Object Set, Layer, Database, Map or Map Window, and Workspace are introduced into the data organization system. Object Set has three types: Simple Object Set, Compound Object Set and Continuous Field. A Layer is a concept related to map display in our holistic GIS software. A Database is defined as a set of stored objects, which is either a small size file or a large-scale database. Map is a frame used to load layers, and can contain multiple layers.A Workspace is a warehouse, which stores basic data info, Maps, Point, Line and Region Symbols,etc. Thirdly, data storage and access mechanism of holistic GIS are introduced. In respect of storage, database table structures of Simple Object Set, Compound Object Set and Field are analyzed, and table structure of 3D data structure and time attribute is also introduced. In order to quicken the pace of accessing to database tables,the spatial index mechanism based on quadtree data structure is built. Further data access mechanism is discussed. Fourthly, SuperMap Deskpro, a GIS software based on holistic data model, is introduced. This software is fulfilled through completely using object-oriented thinking. It can effectively store and access to geographic entities' information including location, attribute, topological relationship and semantic relationship. In respect of Layer Organization, it not only accords with users' direct apperception of geographical world,but also supports users to rationally organize data to meet actual needs. SuperMap Deskpro supports users to use files to store small amount of data, and at the same time users can also use large-scale business database such as SQL Server and Oracle to manage large amount of data.