Change-only Modeling in Navigation Geo-databases

Navigation geo-database is the foundation and vital component of vehicle navigation system. Now almost geo-database is stored in hardware, such as CD, DVD. But, with the development of urban construction, road networks often change, as well as traffic rules. In order to reflect the changes of reality, direct the uses correctly and timely, it’s necessary to update geographic database on time. The common method about map updating is to replace the old database with new one periodically by hardware or internet, and it always takes more than half a year. Actually, many navigation map providers have their own system of data collection and updating. The problem is that they couldn’t deliver the updating data to clients because of lack of map updating model and format. They must process all the changed map data and transform them into certain traditional format, and deliver them to users by DVD or other medias. It’s a hot problem to develop novel methods to support change-only map updating in navigation, and it’s the efficient way to resolve the bottle problem of development with navigation industry. The paper will study on the data model of navigation system to support change-only updating. We develop the change-only concept mode based core GDF road network models with UML schema, analyze the types of changes of road features. Also we discuss the approach of determination of change-only data, define the representation of increment map data in spatial object, property, operation aspects. As such, this model for change-only road data model is allowed to add definitions specifically concerned with change-only road data. The key techniques include: how to identify a feature(mainly road) between different version how to clarify the definition what is change-only data and to give a set of operators responsible for realizing the updating data model for such a data set which can be easily updated by the change-only data data structure for change-only data