An object model with parametric polymorphism for dynamic segmentation

Abstract

Dynamic segmentation is commonly viewed as one of the most effective aspects of GIS for transportation applications. To date, much of this effort has focused on relational data models, with object data models receiving far less attention. This paper presents an object model that provides a natural representation of dynamically segmented features by extending the Object Database Management Group (ODMG) standard with a special mechanism, called parametric polymorphism. This mechanism supports the shifting of a conventional data type into a linear type to maintain knowledge about events (e.g. pavement condition, traffic volumes and traffic accidents) that change spatially along linear features. An associated object query language unavailable in current GIS packages is also provided for data analyes relevant to dynamic segmentation. The model and query language have been implemented using an object-oriented scripting language in a GIS environment.