Methods Of Incremental Updating Based On Change-only Information File

Along with the extending and deeping application of Geographic Information System (GIS ) , the higher requests are put forward about the real time and veracity of the foundational geographic data and spatial data updating has been a hotspot in the field of GIS. Incremental updating will be next major trends of the database because of its flexibility and better way to ensure the real time of spatial data. In view of this, incremental updating approach based on change-only information file is studied in the paper, and the changes in the spatial entities are analysed particularly. On this basis, then, the change-only information file is designed. Finally, updating operation is designed on the base of change-only information file. The main works finished are listed as follows:1) At first, according to the geographic element types of <1:500 1:1000 1:2000 relief map element assorting and code>, the author analyses each changing type of geographic entity and the causes systemically.2) In the base of (GB/T 17798-1999, Geo-spatial data transfer format, shortly CNSTDF)in China, change-only information file is designed initially, including space entity type coding, entity change types coding , incident coding, time of the changes, space and attributes, and other information content.3) Finally, an experiment system is developed using Visual C++ and OPP technology on the platform of VC and MapInfo, and an automated server OO4O ( Oracle Objects for OLE) offered by Oracle and corresponding C++ class libraries are used to make visitation to Oracle come ture, at last actual spatial data is used to examine the methods and models presented in this dissertation. Finally, an experiment system is developed using Visual C++ and OPP technology on the platform of VC and Maplnfo, and an automated server OO4O (Oracle Objects for OLE) offered by Oracle and corresponding C++ class libraries. The incremental organization of practical and simulated spatial data and incremental updating methods are finished. The method of simulation to the actual housing, roads data as an example has been tested in this paper.Study shows incremental updating based on change-only information is a feasible approach to carry out incremental updating of space database.