The Study Of Application Technique Of Combinatorial Object In Cartographic System

The aim of the Cartographic System's development was combining data capturing and updating of geographic information with map publishing. But the data capturing and updating of geographic information were organized by classified code of geographic information, while map publishing data was organized by graphic elements. It was impossible to give attention to those two things in former Cartographic System. In order to meet the cartographic integration, this paper presented that bring combinatorial model in macroscopically data modeling. Designed and applied combinatorial object, integration of map edit could be realized and the consistency requirement of geographic information and map graphic symbols could be contented. It finally becomes the basis of the integrative map production. The main content of this paper is given as follow:Firstly, classical spatial data models were researched. The advantages and disadvantages of models' design and its applying of combinatorial object were analyzed. It offered theories references for integrative modeling with comparing different models used in the aim of applying of combination, the levels of combination and the combinatorial methods.Secondly, the paper presented design of integrative data model based on combinatorial methods. The core of integrative data model was to solve the problem of coexistence of geographic data and publishing data. Thus the geographic layers and the graphic cells layers were used together in the layers model. The problem of geographic data and publishing data edit was solved based on viewports' interconverting. It made edit modifying, elements' query in geographic layers viewport, operation of publishing layers, adjusting relationship of covering and being covered in graphic cells layers viewport possible. Combinatorial geographic information objects were designed. Combinatorial objects were divided into tight type and loose type. In allusion to those two types of objects, the data model and database were designed separately. This provided a base to technique research of using combinatorial objects in map edit.Thirdly, the paper presented the technique research of applying combinatorial objects in map edit. Taking advantages of the structure of combinatorial objects, two methods of maintaining the original consistency of topological relationship and topological relationship processing were taken to fetch up the limitation of traditional topological relationship processing. With the technique support of maintaining the original consistency of topological relationship, geographic information edit kept real time consistency with map graphic symbol edit. Partial topological relationship dealing method just extract and edit topological elements and relative elements, minize the scale of reconstruction of topological relationship. The data quantity is small and improve the efficience of topological relationship.The problem of using simple object to express complicated entities was solved through using combinatorial objects of loose type to describe geographic entities with high complexity in geometry.