A dynamic data model for mobile GIS

A fast response time is a major objective for Mobile Geographic Information System (GIS) applications. This study provides a solution for improving the performance of response time by a dynamic data model. A conceptual dynamic data model is proposed, which covers (a) "position" information of selected geographic objects relevant to the GIS user's interest within his current location, (b) the selected attribute information in which the mobile GIS user is interested. In this approach, first, the attribute information is selected through a validating process making use of the temporal and attribute filters. Second, a specially designed dynamic database is employed to enable the implementation of the conceptual dynamic data model. This dynamic database is continually updated in accordance with the spatial, temporal and attribute constraints specified for the conceptual model. This design of a dynamic data model increases the availability of spatial data to mobile GIS users by providing up to date accurate information relevant to the area of interest, in a limited communication bandwidth. Third, an experimental study has been conducted and the results demonstrate that by using a dynamic database the response time can be reduced to one-third of that of a conventional database. The response time performance can be further improved as the size of the database is increased.