An Approach to Representing Movement Data

Abstract

A moving object is an object of which position changes continuously in space. The movement of an object is represented by the change of its position through space and the change of its attributes over time or location. In temporal geography, the model of space-time cube (STC) represents movements as polylines time-ordered connecting spatio-temporal positions of moving objects. The space-time cubes do not represent attributes of moving objects, which change over time or along trajectories. Several authors used two cubes to represent a moving object, one for spatio-temporal positions and another for attributes changing over location. This article proposes an approach to representing multivariate data of moving objects in a Cartesian coordinate system. The main idea of this article is to join the coordinate system representing location data with the coordinate system representing attributes by sharing the time axis. In this case, attributes that are recorded by the location-based method are inferred visually through the space-time path of the movement. This approach can apply for two cases, given route and ungiven route. For movements of ungiven route, the visualization system combines a 3-dimension system representing locations with a 2-dimension system representing attributes. For movements of given route, the visualization system is a 3-dimension Cartesian coordinate system, where the trajectory is extended as an axis representing the distance from departure place to current place, two other axes indicate time and attributes. In both modes, colors are employed as dimensions to show various attributes. The two modes can be switched reciprocally in a system tracking moving objects on ground.