Compression Methods for Trajectory Data under Road Network Constraints

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Compression Methods for Trajectory Data under Road Network Constraints"

By

Mr. Yudian JI


Abstract

The popularity of location-acquisition devices has led to a rapid increase in 
the amount of trajectory data collected. The large volume of trajectory data 
causes the  difficulties of storing and processing the data. Various trajectory 
compression methods are therefore proposed to deal with these problems. In this 
thesis, we study the problem of trajectory compression under road network 
constraints. We summarize the existing road-network-constrained trajectory 
compression methods and propose a classification based on the features 
leveraged by them. We propose new methods that fill in the research blanks 
indicated by the classification. We conduct a thorough comparison among the 
existing and new road-network-constrained trajectory compression methods. The 
performances of the methods are studied via various metrics on real-world 
datasets. We make new discoveries regarding the performances and the 
scalability of existing methods, and provide guidelines of 
road-network-constrained trajectory compression for various scenarios. We also 
design a new road-network-constrained trajectory compression framework composed 
of several coordinating methods which has an excellent performance in both 
spatial and temporal compression. The framework is also able to support 
location-based services by being able to answer several basic spatio-temporal 
queries. We conduct extensive experiments to verify the efficiency and 
effectiveness of our proposed framework using real-world trajectory data. The 
results strongly advocate the performance of the proposed framework.


Date:			Monday, 24 July 2017

Time:			3:00pm - 5:00pm

Venue:			Room 2130C
 			Lifts 19

Chairman:		Prof. Guanghao Chen (CIVL)

Committee Members:	Prof. Lionel Ni (Supervisor)
 			Prof. Lei Chen (Supervisor)
 			Prof. Shing-Chi Cheung
 			Prof. Qiong Luo
 			Prof. Jingshen Wu (MAE)
 			Prof. Jiannong Cao (Computing, PolyU)


**** ALL are Welcome ****