Time In GIS
This page of the OSGeo Wiki contains some tidbits of information about represting time or working with time in geographic information systems. (This is also known as temporal GIS.) This is not a comprehensive coverage of the topic. It is a collection and summary of responses to a question about temporal GIS that I posted to the OSGeo Discussion Mailing List and Geowanking Mailing List.
The Sunburned Surveyor
Using Linear Referencing To Work With Time In GIS
You can use built-in linear referencing functionality in geographic information systems or relational databases as a "hack" to work with time. A line or other linear geometry is used to represent a "timeline".
Doctor Shih-Lung Shaw (University of Tennessee) and Doctor Hongbo Yu (Oklahoma State) have done some interesting work that use this method to work with events in temporal gis.
PostGIS and GRASS contain this linear referencing functionality:
http://postgis.refractions.net/docs/ch06.html#id3060376
http://grass.osgeo.org/grass63/manuals/html63_user/vectorintro.html
More Than Just Events
Working with time in GIS can involve more than just the concept of an "event" or a single instant in time. It can also involve a chain of events or "history" of an object or feature modeled in a GIS. (For example, a survey monument can be "Set", "Recovered", "Disturbed", and "Destroyed". These are all events. A single survey monument could "own" all of these events, which would form its history.)
Working with time in GIS can also allow us to understand the evolution of objects for features modeled in a GIS. (For example, a railroad can become a pedestrian trail.) This deals with the lineage or heritage of an object or feature. It stores information about what a feature was created from and what it eventually became or evolved into.
This issue was dealt with on the Great Britain Historical GIS:
http://www.visionofbritain.org.uk
http://www.port.ac.uk/research/gbhgis/aboutthegbhistoricalgis/database/
Additional Material
ISO 19108 - Temporal Schema
Time in Geographic Information Systems (A Book Authored By Gail Langran 1992)
Representations Of Space and Time (A Book Authored By Donna Peuguet)
Links
Talk On Time In GIS At FOSS4G In 2006
http://joda-time.sourceforge.net/ Joda (Java Time Programming Library)
Examples
This is a list of examples of combining time and spatial information:
Time & Space Map For Earthquakes
Semi-Functional Application Working With Time, Space, and Biological Observations
Cool Stuff
OGC Stuff
The OGC has some papers that deal with time in GIS. Take a look at OWS 4 WFS Temporal Investigation (06-154) and Temporal Standard Recommendations (06-022r1). You can download PDFs of these two (2) documents here.
Brainstorming
Credits and Thanks
I'd like to thank the following OSGeo members and Geowanking Subscribers for there responses to my question about time in GIS.
Ian Turton
Martin Weis
Vasillis Vlastaras
Brent Fraser
Mikel Maron
Brent Pedersen
Robert Brundage
Grant Pezeshki