Toward a 3D moving object data model-a preliminary consideration

This paper investigates a new data model for the realization of a three-dimensional (3D) moving object database system. In contrast to the traditional approach, it can deal with spatio-temporal characteristics of moving objects in 3D space. A spatio-temporal sampling theory is introduced that enables a database system to store and manipulate all of the necessary spatio-temporal information about moving objects. The 3D moving object database consists of three kinds of relations: a set of primary relations, such as POSI, ORI, GRAD, and SHAPE, store all the essential spatio-temporal features of a single moving object; a set of built-in derived relations, such as DIR, SPEED, TRACK, DIST, MDIR, and TOPOL, store, for example, the motion direction of a single object (DIR) and the topological relation between two objects (TOPOL); and a set of user-defined relations such as BACK and FRONT with which one can issue a variety of spatio-temporal queries on moving objects. A domain relational calculus-based moving object query language named MOQL is shown