Jun Luo

• PhD
• Principal Investigator at Lenovo Group Limited, Hong Kong

Given historical traffic distributions and associated urban conditions observed in a city, the conditional urban traffic estimation problem aims at estimating realistic future projections of the traffic under a set of new urban conditions, e.g. , new bus routes, rainfall intensity and travel demands. The problem is important in reducing traffic con...

Enhancing diverse human decision-making processes in an urban environment is a critical issue across various applications, including ride-sharing vehicle dispatching, public transportation management, and autonomous driving. Offline reinforcement learning (RL) is a promising approach to learn and optimize human urban strategies (or policies) from p...

Urban traffic status (e.g., traffic speed and volume) is highly dynamic in nature, namely, varying across space and evolving over time. Thus, predicting such traffic dynamics is of great importance to urban development and transportation management. However, it is very challenging to solve this problem due to spatial-temporal dependencies and traff...

Emergence of autonomous vehicles (AVs) offers the potential to fundamentally transform the way how urban transport systems be designed and deployed, and alter the way we view private car ownership. In this article we advocate a forward-looking, ambitious and disruptive smart cloud commuting system (SCCS) for future smart cities based on shared AV...

Smart passenger-seeking strategies employed by taxi drivers contribute not only to drivers’ incomes, but also higher quality of service passengers received. Therefore, understanding taxi drivers’ behaviors and learning the good passenger-seeking strategies are crucial to boost taxi drivers’ well-being and public transportation quality of service. H...

The rapid progress of urbanization has expedited the process of urban planning, e.g. , new residential, commercial areas, which in turn boosts the local travel demand. We propose a novel “off-deployment traffic estimation problem”, namely, to foresee the traffic condition changes of a region prior to the deployment of a construction plan. This pr...

Many real-world human behaviors can be modeled and characterized as sequential decision-making processes, such as a taxi driver’s choices of working regions and times. Each driver possesses unique preferences on the sequential choices over time and improves the driver’s working efficiency. Understanding the dynamics of such preferences helps accele...

Given a set of user-specified locations and a massive trajectory dataset, the task of mining spatio-temporal reachable regions aims at finding which road segments are reachable from these locations within a given temporal period based on the historical trajectories. Determining such spatio-temporal reachable regions with high accuracy is vital for...

Skyline computation, aiming at identifying a set of skyline points that are not dominated by any other point, is particularly useful for multi-criteria data analysis and decision making. Traditional skyline computation, however, is inadequate to answer queries that need to analyze not only individual points but also groups of points. To address...

We present SkyRec (Skyline Recommender), a recommendation toolkit for finding optimal groups based on the notion of group skyline. Skyline computation, aiming at identifying a set of skyline points that are not dominated by any other point, is particularly useful for multi-criteria data analysis and decision-making. Traditional skyline computation,...

Identifying urban gathering events is an important problem due to challenges it brings to urban management. In our prior work, we proposed a hybrid model (H-VIGO-GIS) to predict future gathering events through trajectory destination prediction. Our approach consisted of two models: historical and recent and continuously predicted future gathering e...

Many real-world human behaviors can be characterized as a sequential decision making processes, such as urban travelers choices of transport modes and routes (Wu et al. 2017). Differing from choices controlled by machines, which in general follows perfect rationality to adopt the policy with the highest reward, studies have revealed that human agen...

Skyline queries are important in many application domains. In this paper, we propose a novel structure Skyline Diagram, which given a set of points, partitions the plane into a set of regions, referred to as skyline polyominos. All query points in the same skyline polyomino have the same skyline query results. Similar to $k^{th}$ -order Voronoi d...

k$ nearest neighbor ($k$NN) queries and skyline queries are important operators on multi-dimensional data points. Given a query point, $k$NN query returns the $k$ nearest neighbors based on a scoring function such as a weighted sum of the attributes, which requires predefined attribute weights (or preferences). Skyline query returns all possible ne...

Skyline queries are important in many application domains. In this paper, we propose a novel structure Skyline Diagram, which given a set of points, partitions the plane into a set of regions, referred to as skyline polyominos. All query points in the same skyline polyomino have the same skyline query results. Similar to $k^{th}$-order Voronoi diag...

A traffic congestion in a road network may propagate to upstream road segments. Such a congestion propagation may make a series of connected road segments congested in the near future. Given a spatial-temporal network and congested road segments in current time, the aim of predicting traffic congestion propagation pattern is to predict where those...

Given a set of objects O (e.g., hotels), each can be represented as a point in a multi-dimensional feature space where each dimension corresponds to one attribute of the objects (such as price). Given the preference of a customer, the objects in O not dominated by any other object (i.e., beat in all dimensions) are those worthy to be further consid...

Rapid urbanization has posed significant burden on urban transportation infrastructures. In today's cities, both private and public transits have clear limitations to fulfill passengers’ needs for quality of experience (QoE): Public transits operate along fixed routes with long wait time and total transit time; Private transits, such as taxis, priv...

Given a trajectory database and a pair of upstream and downstream spatio-temporal (ST) regions (i.e., spatial area coupled with a time interval), a TTA query aims to retrieve the total number of unique trajectories that traverse through these two ST regions. Such TTA queries play an important role in various urban applications, such as route planni...

Rapid urbanization has posed significant burden on urban transportation infrastructures. In today's cities, both private and public transits have clear limitations to fulfill passengers' needs for quality of experience (QoE): Public transits operate along fixed routes with long wait time and total transit time; Private transits, such as taxis, priv...

Urban gathering events such as social protests, sport games, and traffic congestions bring significant challenges to urban management. Identifying gathering events timely is thus an important problem for city administrators and stakeholders. Previous techniques on gathering event detection are mostly descriptive, i.e., using realtime on-site observ...

The $k$ nearest neighbor ($k$NN) query is a fundamental problem in databases. Given a set of multidimensional data points and a query point, $k$NN returns the $k$ nearest neighbors based on a scoring function such as weighted sum given an attribute weight vector. However, the attribute weight vector can be difficult to specify in practice. Skyline...

Travelling is a critical component of daily life. With new technology, personalized travel route recommendations are possible and have become a new research area. A personalized travel route recommendation refers to plan an optimal travel route between two geographical locations, based on the road networks and users’ travel preferences. In this pap...

The fast pace of urbanization has given rise to complex transportation networks, such as subway systems, that deploy smart card readers generating detailed transactions of mobility. Predictions of human movement based on these transaction streams represents tremendous new opportunities from optimizing fleet allocation of on-demand transportation su...

Indexing moving objects has been extensively studied in the past decades. In most real world applications, the moving objects exhibit particular patterns on their velocities. For example, velocities of vehicles in city road networks usually show patterns on both directions and values. Velocity-based partitioning techniques have been proved effectiv...

Skyline is a set of points that are not dominated by any other point. Given uncertain objects, probabilistic skyline has been studied which computes objects with high probability of being skyline. While useful for selecting individual objects, it is not sufficient for scenarios where we wish to compute a subset of skyline objects, i.e., a skyline s...

Skyline computation, aiming at identifying a set of skyline points that are not dominated by any other point, is particularly useful for multi-criteria data analysis and decision making. Traditional skyline computation, however, is inadequate to answer queries that need to analyze not only individual points but also groups of points. To address thi...

Sketch matching is the fundamental problem in sketch based interfaces. After years of study, it remains challenging when there exists large irregularity and variations in the hand drawn sketch shapes. While most existing works exploit topology relations and graph representations for this problem, they are usually limited by the coarse topology expl...

With the success of social media, social network analysis has become a very hot research topic and attracted much attention in the last decade. Most studies focus on analyzing the whole network from the perspective of topology or contents. However, there is still no systematic model proposed for multi-dimensional analysis on big social media data....

Electric vehicles (EVs) have undergone an explosive increase over recent years, due to the unparalleled advantages over gasoline cars in green transportation and cost efficiency. Such a drastic increase drives a growing need for widely deployed publicly accessible charging stations. Thus, how to strategically deploy the charging stations and chargi...

Recommending routes with the shortest cruising distance based on big taxi trajectories is an active research topic. In this paper, we first introduce a temporal probability grid network generated from the taxi trajectories, then a profitable route recommendation algorithm called Adaptive Shortest Expected Cruising Route (ASECR) algorithm is propose...

Given a set of n points, each is painted by one of the k given colors, we want to choose k points with distinct colors to form a color spanning set. For each color spanning set, we can construct the convex hull and the smallest axis-aligned enclosing rectangle, etc. Assume that each point is chosen independently and identically from the subset of p...

Skyline computation, aiming at identifying a set of skyline points that are not dominated by any other point, is particularly useful for multi-criteria data analysis and decision making. Traditional skyline computation, however, is inadequate to answer queries that need to analyze not only individual points but also groups of points. To address thi...

Research on congestion propagation in large urban networks has been based mainly on microsimulations of link-level traffic dynamics. However, both the unpredictability of travel behavior and the complexity of accurate physical modeling present challenges, and simulation results may be time-consuming and unrealistic. This paper explores empirical da...

Indexing moving objects has been extensively studied in the past decades. However, none of the existing work considers the distribution of the speed values of the moving objects. Actually, in most applications, moving objects, such as pedestrians, vehicles, and airplanes, have their typical speed ranges. In this paper, we propose a novel index part...

The maximum diameter color-spanning set problem (MaxDCS) is defined as follows: given n points with m colors, select m points with m distinct colors such that the diameter of the set of chosen points is maximized. In this paper, we design an optimal O(n log n) time algorithm using rotating calipers for MaxDCS in the plane. Our algorithm can also be...

In recent years, social media has become important and omnipresent for social network and information sharing. Researchers and scientists have begun to mine social media data to predict varieties of social, economic, health and entertainment related real-world phenomena. In this paper, we exhibit how social media data can be used to detect and anal...

The pervasive usage of LBS (Location Based Services) has caused serious risk of personal privacy. In order to preserve the privacy of locations, only the anonymized or perturbated data are published. At the same time, the data mining results for the perturbated data should keep as close as possible to the data mining results for the original data....

In a normal Voronoi diagram, each site is able to see all the points in the plane. In this paper, we study the case such that each site is only able to see a visually restricted region in the plane and construct the so-called Visual Restriction Voronoi Diagram (VRVD). We show that the visual restriction Voronoi cell of each site is not necessarily...

With the development of information technologies, Social Media platforms have become popular and accumulated numerous data about individuals’ behavior. It offers a promising opportunity of discovering usable knowledge about the individuals’ movement behavior, which fosters novel applications and services. In this paper, in order to study the relati...

Given a set of points Q in the plane, define the \(\frac{r}{2}\)-Disk Graph, Q(r), as a generalized version of the Unit Disk Graph: the vertices of the graph is Q and there is an edge between two points in Q iff the distance between them is at most r. In this paper, motivated by applications in wireless sensor networks, we study the following geome...

In this paper* we illustrate a privacy framework named Indistinguishable Privacy. Indistinguishable privacy could be deemed as the formalization of the existing privacy definitions in privacy preserving data publishing as well as secure multi-party computation. We introduce three representative privacy notions in the literature, Bayes-optimal priva...

With the advent of location-based social media and location-acquisition technologies, trajectory data are becoming more and more ubiquitous in the real world. Trajectory pattern mining has received a lot of attention in recent years. Frequent sub-trajectories, in particular, might contain very usable knowledge. In this paper, we define a new trajec...

With the rapid development of location sensing technology such as GPS, huge amount of location data through GPS are produced every day. The flood of taxi GPS data make it possible to predict the plentitude of traffic events on road network. In this paper, we propose a data-driven approach for traffic state convergence prediction on road network. We...

In this paper we illustrate a privacy framework named Indistinguishable Privacy. Indistinguishable privacy could be deemed as the formalization of the existing privacy definitions in privacy preserving data publishing as well as secure multi-party computation. We introduce three variants of the representative privacy notions in the literature, Baye...

The maximum diameter color-spanning set problem (MaxDCS) is defined as follows: given n points with m colors, select m points with m distinct colors such that the diameter of the set of chosen points is maximized. In this paper, we design an optimal O(nlogn) time algorithm using rotating calipers for MaxDCS problem in the plane. Our algorithm can a...

This book constitutes the thoroughly refereed proceedings of the PAKDD 2012 International Workshops: Third Workshop on Data Mining for Healthcare Management (DMHM 2012), First Workshop on Geospatial Information and Documents (GeoDoc 2012), First Workshop on Multi-view data, High-dimensionality, External Knowledge: Striving for a Unified Approach to...

Data collected from mobile phones have potential knowledge to provide with important behavior patterns of individuals. In this paper, we present approaches to discovering personal mobility and characteristics based on mobile phone location information and semantic analysis. We discuss three aspects related to very common mobile phone-related applic...

Spatially aggregated data is frequently used in geographical applications. Often spatial data analysis on aggregated data is performed in the same way as on exact data, which ignores the fact that we do not know the actual locations of the data. We here propose models and methods to take aggregation into account. For this we focus on the problem of...

As a major online interactive platform, microblogs have accumulated numerous data about people's interactive behaviors, which have attracted many researchers to study these data. However, the existing studies mainly focus on the community structure detection or information propagation from the conventional perspective of social network analysis. Fe...

Microblog has become ubiquitous for social networking and information sharing. A few studies on information propagation over microblog reveal that the majority of users like to publish and share the news on microblog. The public opinion over the internet sometimes plays important role in national or international security. In this paper, we propose...

In a normal Voronoi diagram, each site is able to see all the points in the plane. In this paper, we study the case such that each site is only able to see a visually restricted region in the plane and construct the so-called Visual Restriction Voronoi Diagram (VRVD). We show that the visual restriction Voronoi cell of each site is not necessary co...

Routing problem has been studied for decades. In this paper, we focus on one of the routing problems: finding a path from source to destination on road network with the guidance of landmarks. People use landmarks to identify previously visited places and reoriented themselves in the environment. When people give direction instructions for other peo...

DBSCAN is a well-known density-based clustering algorithm which offers advantages for finding clusters of arbitrary shapes compared to partitioning and hierarchical clustering methods. However, there are few papers studying the DBSCAN algorithm under the privacy preserving distributed data mining model, in which the data is distributed between two...

Road network analysis can require distance from points that are not on the network themselves. We study the algorithmic problem of connecting a point inside a face (region) of the road network to its boundary while minimizing the detour factor of that point to any point on the boundary of the face. We show that the optimal single connection (feed-l...

Let P be a simple polygon of n vertices and let S be a set of N points lying in the interior of P. A geodesic disk GD(p, r) with center p and radius r is the set of points in P that have a geodesic distance ≤ r from p (where the geodesic distance is the length of the shortest polygonal path connection that lies in P). In this paper we present an ou...

Motivated by the insufficiency of the existing framework that could not process multiple attributes with different sensitivity requirements on modeling real world privacy requirements for data publishing, we present a novel method, rating, for publishing sensitive data. Rating releases AT (Attribute Table) and IDT (ID Table) based on different sens...

A natural time-dependent similarity measure for two trajectories is their average distance at corresponding times. We give algorithms for computing the most similar subtrajectories under this measure, assuming the two trajectories are given as two polygonal, possibly self-intersecting lines. When a minimum duration is specified for the subtrajector...

Data collected from real world are often imprecise. A few algorithms were proposed recently to compute the convex hull of maximum area when the axis-aligned squares model is used to represent imprecise input data. If squares are non-overlapping and of different sizes, the time complexity of the best known algorithm is O(n 7). If squares are allowed...

Aligning and comparing two polygonal chains in 3D space is an important problem in many areas of research, like in protein structure alignment. A lot of research has been done in the past on this problem, using RMSD as the distance measure. Recently, the discrete Fréchet distance has been applied to align and simplify protein backbones (geometrical...

Consider a scenario like this: a data holder, such as a hospital (data publisher) wants to share patients' data with researcher (data user). However, due to privacy issue, the hospital could not publish the exact original data while the published data need to retain as much as possible the correlation of the original data for utility consideration....

In normal Voronoi diagram, each site is able to see all points in the plane. In this paper, we study the problem such that each site is only able to see half-plane and construct the so-called Half-plane Voronoi Diagram (HPVD). We show that the half-plane Voronoi cell of each site is not necessary convex and it could consist of many disjoint regions...

Influence analysis and expert finding have received a great deal of attention in social networks. Most of existing works, however, aim to maximize influence based on communities structure in social networks. They ignored the location information, which often imply abundant information about individuals or communities. In this paper, we propose Info...

Jack and Jill want to play hide-and-seek on the boundary of a simple polygon. Given arbitrary paths for the two children along this boundary, our goal is to determine whether Jack can walk along his path without ever being seen by Jill. To solve this problem, we use a linear-sized skeleton invisibility diagram to implicitly represent invisibility i...

We study the problem of moving network Voronoi diagram: given a network with n nodes and E edges. Suppose there are m sites (cars, postmen, etc) moving along the network edges, we design the algorithms to compute the dynamic network Voronoi diagram as sites move such that we can answer the nearest neighbor query efficiently. Furthermore, we extend...

In this paper we consider the problem of detecting commuting patterns in a trajectory. For this we search for similar subtrajectories. To measure spatial similarity we choose the Fréchet distance and the discrete Fréchet distance between subtrajectories, which are invariant under differences in speed. We give several approximation algorithms, and a...

In this paper we study several geometric problems of color-spanning sets: given N points with M colors in the plane, choosing M points with distinct colors such that some geometric properties of those M points are minimized or maximized. The geometric properties studied in this paper are the maximum diameter, the largest closest pair, and the minim...

There are n points in the plane and each point is painted by one of m colors where m ≤ n. We want to select m different color points such that (1) the total edge length of resulting minimal spanning tree is as small as possible; or (2) the total edge length of resulting minimal spanning tree is as large as possible; or (3) the perimeter of the conv...