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:

www.visionofbritain.org.uk http://www.port.ac.uk/research/gbhgis/aboutthegbhistoricalgis/database/

Additional Material

ISO 19108 - Temporal Schema Time in Geographic Information Systems (Book Authored By Langran and Gail in 1992)

Links

Talk On Time In GIS At FOSS4G In 2006 Joda (Java Time Programming Library)

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 Freaser

Mikel Maron

Brent Pedersen

Robert Brundage