Spatial-temporal Data Model and Related Theoretic Issues
Feng Kezhong · Geo-information Science · 2004
Most of the geographical information systems are based on the static data model but with restrictions when they operate with dynamic information. Only the current status of an entity will be kept and the historical data will be lost during updating because the current GIS data model is lacking ability in tracking the evolution of an entity. We only know what it currently is, we know nothing about its past. The current data models that nowadays GIS use are nothing but snapshot data models.With the widespread use of GIS in many related geographic fields, people begin to realize that GIS should have ability to describe the spatiotemporal changes that are taking place every day in our world, so historical analysis could be achieved and even future evolution trend of phenomenon could be predicted. This idea brings forth the concepts of Spatiotemporal Geographical Information System(STGIS) and spatiotemporal data model(STDM).This paper reviews the progress that has been made in spatiotemporal data modeling. Related concepts have been introduced in details, technical issues in spatiotemporal data modeling and STGIS have been analyzed. Two main kinds of spatiotemporal data models are discussed, namely version-based spatiotemporal data models and object-oriented spatiotemporal data models. This paper points out that lack of a perfect spatiotemporal data model is a main obstacle in STGIS development and the basic requirements for a spatiotemporal data model has been investigated from system aspect and design aspect. Historical retrospect and time sequence description ability are the most essential ones among these requirements. This paper concludes that in spatiotemporal data modeling, object-oriented modeling method should be used and the implementation of such a spatiotemporal data model should be based on state-of-the-art database technologies.