Comments on: The Revival of Time Geography

By: Andrew Turner

Andrew Turner — Mon, 19 Jun 2006 00:03:47 +0000

Very interesting ideas and information about the “time prism”. Within this prism you could have decreasing radius as your time at the location increased. A great way to visualize spatial possibilities and planning.

As for the “geocoded calendar”, check out SpeedLimit: http://betimely.com. It ties in your GoogleCalendar, or any iCalendar file with locations to route you to your appointments and alert you when you need to leave.

By: Sven Teßmann

Sven Teßmann — Sat, 25 Mar 2006 22:37:35 +0000

Nice to find something about time geography here - for my thesis I’m currently looking at mapping these concepts to transportation networks. One would think that the lower dimensionality makes life easier: well it doesn’t. When calculating the network analogs (PPT/PNA) of the original concepts you run into serious algorithm complexity issues. For instance calculation of shortest-path based subgraphs for every time interval.

As Miller mentions “[...] for detailed urban-scale applications, especially for real-time applications (such as LBS) or data mining and visualization [...]” more efficient methods must be found.

Nevertheless I think interesting applications are possible and, like you wrote, a mathematical model is available.

P.S.: Nice idea with the gisblog !

By: Carsten Keßler

Carsten Keßler — Wed, 15 Mar 2006 12:20:57 +0000

You are right - the model behind time geography is what it makes particularly interesting for mobile applications. But it is not yet fully understood how to treat the model mathematically. Miller has done a good part of the work in the paper mentioned above.

Concerning visualisation over a longer period of time, you would certainly have a lower spatial granularity. If you look at a person’s path for, let’s say, a year, you are probably interested in longer trips. And once you want to visualise more than just a few paths, it becomes pretty confusing, of course. But as this was designed for the individual level, I don’t think this is a real problem.

I don’t know the Rinner paper, but I will have a look at it.

By: Patrick Maué

Patrick Maué — Wed, 15 Mar 2006 12:10:57 +0000

Good read. I am not quite sure about the visualisation though. As long as you just want to show the path of one individual its good, but integrating more paths or displaying longer time periods makes it pretty complex. Claus Rinner implemented a nice VRML application [1], which allowed dynamic interaction with the mapviewer to assist the user in this aspect.

I think these two visualisations methods should be better taken as models, which you should reconsider if you have to implement time-dependent GIS applications. Especially if you are developing for mobile hardware.

[1] Claus Rinner (2004): Three-Dimensional Visualization of Activity-Travel Patterns