Comparison of Distance Functions for Similarity Measurement in Spatial Trajectories

A spatial trajectory is a record of moving object’s spatial changes through time and is modeled by a sequence of discrete points with spatio-temporal coordinates. Increasing number of moving objects and positioning technologies resulted in immense number of spatio-temporal data needing various analyses. Extracting similar trajectories is one of the crucial analyses in spatial trajectories. So far various distance functions have been proposed for measuring similarity where each one has addressed similarity from its own point of view and is suitable for particular data with special characteristics. Thus, functions effectiveness is not the same for all kind of data and applications and understanding capabilities and characteristics of functions is the prerequisite of choosing the suitable function. In this paper, a comparative experimental study is conducted on the effectiveness of seven widely used trajectory similarity measures which are the base of many other former proposed distance functions and their advantages and drawbacks are discussed.