A GIS-based Time-geographic Framework for Spatio-temporal ...

A GIS-based Time-geographic Framework for 

Spatio-temporal temporal Analysis of 

Individual Activities and Interactions 

Shih-Lung Shaw 

Department of Geography, University of Tennessee 

Knoxville, TN 37996 Email: sshaw@utk.edu 

Hongbo Yu 

Department of Geography, Oklahoma State University 

Stillwater, OK 74078 Email: hongbo.yu@okstate.edu 

Third Meeting on ICT, Everyday Life and Urban Change 

Coombe Lodge, Bristol, UK, March 16-19, 2008

Acknowledgement: 

• This research is funded by U.S. NSF Grant #BCS- 

0616724. 

• We thank Glenn Lyons, the Faculty of the Built 

Environment, and the Centre for Transport & Society at 

the University of the West of England for organizing and 

hosting this meeting. 

Shaw & Yu, Third ICT Meeting, Bristol, UK, March 16-19, 2008

Research Background: 

• Many researchers have made contributions to the study of 

how ICT affect human activities in everyday life and their 

implications to urban, economic and social systems. 

• An increasing number of empirical studies with detailed 

data collected at the individual level are being conducted. 

• Time geography has been suggested as one useful 

approach to pursuing this research topic. However, 

classical time geography falls short of representing and 

analyzing activities and interactions in virtual space. 

• We need a versatile space-time analytical environment to 

support empirical studies based on the time-geographic 

approach. 


A Brief Review of Time Geography: 

• Hägerstrand’s (1970) time geography provides a useful 

framework for studying individual activities under 

different constraints (capability, authority, and coupling 

constraints) in a space-time context. 

• Three types of constraints: 

Capability 

constraints 

Authority 

constraints 

Coupling 

constraints 

Physiological necessities: sleep, eat, etc. 

Capabilities: auto ownership, physical disability, etc. 

Access restrictions: 

restricted areas, open hours of a shopping mall, etc. 

Requirement of concurrence in space and time 

face-to-face meeting 


• Some key concepts of Time Geography: 

– Space-time path (ST path) 

– Space-time prism (ST prism) 

– Potential path area (PPA) 

time 

time 

Space-Time Path 

t2 

Space-Time Prism 

3 

space 

t1 

space 

1 

2 

Potential Path Area 


Information and Communications 

Technologies (ICT): 

• Information and communications technologies (ICT), 

such as cell phones and the Internet, have introduced 

important changes to the ways that activities are carried 

out. 

• While transportation serves as the means of carrying out 

activities in physical space, ICT provide the means for 

individuals to perform activities in virtual space. 

• Interactions between physical and virtual activities take 

place in a space-and-time context. 


• Spatio-temporal processes and patterns: 

– Physical activities and virtual activities mutually influence 

each other. 

– Fragmentation of activities (Couclelis 2004): suggests 

different spatio-temporal activity patterns 

physical space 

Transportation 

virtual space 

ICT 


• “Other (capability) constraints ... Enable the time-space 

surrounding of an individual to be divided up into a series 

of ‘concentric’ tubes or rings of accessibility, the radii of 

which depend on his ability to move or communicate ...” 

(Hägerstrand, 1970, p. 12) 

• “I am sure that we are still far from understanding the 

locational implications of the next enlargement of the 

range of this tube (i.e., telecommunications), which have 

entirely broken up this once so narrow spatial boundary.” 

(Hägerstrand, 1970, p. 12) 


Research Objectives: 

• Extend the classical time-geographic concepts to cover 

activities and interactions in a hybrid physical-virtual 

space. 

• Design a space-time GIS framework that is capable of 

representing and visualizing activities and interactions in 

both physical and virtual spaces. 

• Develop GIS functions that can capture activities and 

interactions as processes and can support spatiotemporal 

analysis of individual activities and 

interactions. 


Implication to Space-Time Path: 

• With ICT, individuals are no 

longer confined to the spatial 

proximity along their spacetime 

path. 

time 

email 

travel 

• We must represent both 

physical and virtual activities 

in an integrated space-time 

environment. 

– Not only activities at specific 

locations/time, but also 

relationships with other 

individuals and/or entities 

e-shopping 

cell phone call 

travel 

space 

ST Path 


Spatio-temporal temporal Representations in GIS: 

• 3 dimensional spatio-temporal features: 2D space + 1D time 

– ST point feature: (x, y, t ) 

– ST line feature: {(x 1 , y 1 , t 1 ), (x 2 , y 2 , t 2 ), …, (x n , y n , t n )}, 

where t 1

Representation of Individual Activities in GIS: 

• Represent individual activities on a space-time path using 

spatio-temporal linear referencing and dynamic 

segmentation 

time 

6 

7 

4 

space-time path 

5 

Physical activities: 

1. Drive to work 

3. Have lunch 

4. Drive back home 

6. Grocery shopping 

7. Return home 

3 

1 

2 

space 

Virtual activities: 

2. Instant messaging with colleagues 

5. Receive a cell phone call from 

spouse to do grocery shopping 


individual 

human activities 

space-time paths 



Concepts of Stations and Bundles: 

• A station is a location in space where paths can bundle 

for some activity. This usually corresponds to a 

designated location such as a retail outlet, office, or 

home.” (Miller, 2005, E&P-B, p. 386) 

• “Stations have different physical extent in time and 

space and are represented as tubes of varying size, …” 

(Golledge and Stimson, 1997, p. 272) 

• Hägerstrand (1970) discussed bundle within the context 

of coupling constraints. An individual forms a bundle 

with other individuals and/or entities because they need 

to be coupled together to participate in a specific 

activity. 


• The concepts of station, bundle, and coupling constraint 

are closely related to each other in classical time 

geography. 

• In physical space, we can identify stations and bundles 

by examining the spatial and temporal proximities 

among individual space-time paths. 

– stationary stations/bundles (e.g., offices, homes) 

– mobile stations/bundles (e.g., carpools, bus rides, family 

trips) 

– can help derive potential relationships among individuals 



present 

Rural-urban continuum a la Beale 

past 

Migration Data Set: Northern Plains survey data 

over 2,800 individuals/11,000 moves, ~ 90 years 



Stations and Bundles in Virtual Space: 

• “A further kind of bundle deserves some passing 

comments. Telecommunication allows people to form 

bundles without (or nearly without) loss of time in 

transportation.” (Hägerstrand, 1970, p. 15) 

• Bundles in virtual space can be defined as “clusters of 

individuals and/or entities that share virtual interactions 

with each other.” (e.g., teleconference, online interactive 

game – World of Warcraft) 

• Stations in virtual space can be defined as “locations in 

virtual space where individuals and/or entities are 

bundled together to participate in a virtual activity.” (e.g., 

MySpace) 


- Visualize spatiotemporal 

patterns 

of individual 

activities and 

interactions 

- Manage and 

analyze individual 

activity and 

interaction data in 

a space-time 

context 


• We identify stations and bundles in virtual space based 

on the relationships among individual space-time paths 

instead of the proximities among them. 

• In classical time geography, a person can be at only one 

location at a time. In virtual space, a person can form 

virtual bundles at multiple virtual stations at the same 

time. 


Space-Time Prism in Physical & Virtual Space: 

• With ICT, individuals are no 

longer constrained by the 

physical space-time prism. 

• What is the equivalent of 

space-time prism in virtual 

space? 

– Not “anywhere & anytime” 

due to various constraints 

(e.g., language barrier, 

members-only sites, no 

service) 

– A “Swiss cheese model” 

time 

t2 

t 

t1 

accessible 

site/area 

virtual space 

ST Prism for virtual activities 


(Credit: This slide is contributed by Dr. Zhixiang Fang.) 



Activities, Events, and Projects: 

• In time geography, everything being done (including 

“doing nothing”) is considered an activity. 

• Human activities are often organized in some temporal 

orders such that we can accomplish various tasks. 

• It therefore is important to view human activities as 

processes rather than independent events. 

• “Projects are composed of a series of tasks and act as 

the vehicle for goal achievement. ..… The pursuit of 

projects involves events and actions that are 

incorporated into an individual’s path.” (Golledge and 

Stimson, 1997, p. 271) 


• A project can consist of activities that involve only one 

participant or multiple participants. 

• When a project involves multiple participants, it is better 

to organize the activities as a set of events. 

• An event (e.g., a basketball game) consists of activities 

associated with multiple participants (e.g., players, 

referees, cheerleaders, and audience). These participants 

carry out different activities at the event. 

• A project (e.g., organize a conference) consists of a 

sequence of events (e.g., call for papers, registration, 

conference meeting) that may be disjoint in space and/or 

time (i.e., fragmentation of activity). 


• Each activity is identified as either a physical activity or 

a virtual activity. It also can record the initiator and the 

receiver of an activity. 

• This design allows us to represent, manage, and analyze 

activities that occur in physical and virtual spaces, events 

that involve multiple individuals/activities, and projects 

that consist of multiple events. 


A Space-time GIS Design 



Spatio-temporal temporal Analysis: 

• Human activities clearly have both spatial and temporal 

dimensions and should be analyzed in a space-time 

context. 

• Two types of sptio-temporal analysis functions we have 

been working on: 

– Analyze the spatio-temporal patterns and interactions of 

large empirical dataset of individual activities (e.g., Yu, 

2006; Yu & Shaw, 2007; Shaw & Yu, under review) 

– Provide useful spatio-temporal analysis functions for 

various application domains (e.g., assess physical and 

virtual opportunities for individuals). 


An Example of Analyzing Spatio-temporal 

temporal 

Relationships: 

• With ICT, people can participate in activities through telepresence 

in addition to the conventional physical presence. 

• Literature identifies four types of communication modes based 

on their spatial and temporal characteristics (Janelle, 1995; 

Harvey and Macnab, 2000; Miller, 2003) . 

Spatial 

Temporal Physical presence Tele-presence 

Synchronous 

SP (Co-existence) 

• Face-to-face meeting 

ST (Co-location in time) 

• Telephone 

• Instant messaging 

Asynchronous 

(Source: adapted from Miller, 2003) 

AP (Co-location in space) 

• Post-it note 

• Bulletin board 

AT (No co-location in 

space or time) 

• E-mail 

• Voice mail 


Spatio-temporal temporal Relationships of Human Activities: 

• Four types of human interactions based on their spatio-temporal 

relationships and represented by extended space-time paths: 

time 

t2 

t1 

SP (co-existence) 

space 

time 

AP (co-location in space) 

space 

time 

ST (co-location in time) 

AT (no co-location in either space or time) 

time 

t2 

t1 

space 

space 


SP 

(co-existence) 

AP 

(co-location in space) 

ST 

(co-location in time) 

AT 

(no co-location 

In either space 

or time) 


Exploratory Analysis of ST Relationships: 

time 

time 

T5 

T6 

T 

L1 

L2 

T4 

T interpolate 

T3 

A 

T1 T2 

space 

space 

Find locations of ST paths at time T 

Locate time for point A on the ST path 

time 

time 

P 

L 

space 

space 

Find ST paths visiting location L 

Find ST paths interacting with person P 


space-time path 

of Prof D 

Department of 

Geography 

Co-location in space 

analysis 


An Example of Assessing Physical & Virtual 

Activity Opportunities: 

• People and entities (e.g., workplaces, stores) are located 

at different physical locations in Knoxville. 

• Let’s assume that different students want to buy a 

particular product, say, Kodak Z812 digital camera. 

• Let’s also assume that people with access to the Internet 

have options of doing information search and online 

purchase. 

• Can we analyze their physical and virtual activity 

opportunities using the GIS-based time-geographic 

system? 





Conclusion: 

• This GIS-based time-geographic framework: 

– extends the concepts of time geography to cover 

activities and interactions in a hybrid physical-virtual 

space; 

– provides a space-time GIS framework for representing 

and managing individual activity data in an integrated 

space-time environment; and 

– offers a foundation for developing spatio-temporal 

analysis functions. 

• We would like to collaborate with researchers who have 

empirical data to put this space-time GIS into practical 

uses. 


Thank You! 

For additional information about this research, 

please visit our web site at: 

http://web.utk.edu/~sshaw/NSF-Project 

Project-Website/default.htm

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