Classification and Representation of Change in Spatial Database for Incremental Data Transfer

Nowadays, more and more spatial databases are used in various fields, so the demands for keeping spatial database “fresh” are growing rapidly. Generally, the end-users get the basic spatial data from professional spatial data producers. There are mainly two kinds of way for transfer the changed data. One is to batch transfer; the other is incremental data transfer. With the batch method, the whole up-to-date database is delivered. This process is time-consuming and might induce significant risks of errors occurrence and information loss.. Recent years, more and more people begin to study incremental updating of spatial database. This method of updating makes it possible to transfer change-only information to the end-users, namely to transfer the incremental data. In order to find out the changed objects in a database, firstly we need to identify uniquely all of the objects. In this paper, we define a geographical object as a new 4-tuple {semantic descriptor, thematic descriptor, spatial descriptor, and temporal descriptor}. Spatial descriptor consists of geometric component, position component and topologic component. What change happens to an object? In order to answer this question, firstly, we have to identity and classify changes of geographical objects. Based on the 4-tuple model of geographical object, we propose taxonomy of the change of geographical object and describe these changes with data/knowledge packets.