Bin,
As I understand it the real problem is with the spatial resolution and
geography of cell data. The phone company has data on cell handovers, but
they don’t know with any precision (they say) where the cell boundaries are.
Cells overlap and signals bounce off buildings etc. so the geography of
cells is very messy. It also varies depending on demand - a cell that has a
lot of traffic may delay accepting handover from neighbours. Carlo Ratti's
animations of cell occupancy overlaid on maps of Milan shows the extent of
what one can do easily with the data at the moment - ie. generalised contour
maps at an aggregate population level with neither spatial (street) nor
individual person resolution. Gives a nice view of populations ebbing and
flowing over time though.
GPS data are much nicer... We are working on the Cityware project with
Naranker Dulay, Markus Huebscher and Morris Sloman at Imperial College who
have taken a different approach. They have written an application (a context
logger or "Clogger") for your smartphone which logs your GPS location, IDs
of Bluetooth devices you can see, cell ids, WiFi nodes visible, phone calls,
pictures you have taken, diary appointments, emails and SMS messages etc.
etc. continuously and uploads these to a webpage. It does wonders for your
phone bill and battery life, but also gives beautiful data on what you are
doing with whom, where and when as you move around the city. The problem
(apart from the bill) is that programming phones is tricky and needs to be
redone for different devices. But Clogger is open source so hopefully there
may be people out there who will take on that task...
Alan Penn
[log in to unmask]
www.vr.ucl.ac.uk
www.spacesyntax.org
>
> Dear all,
>
> I am very happy to see so many responses on the real time maps (I was
> away for the Chinese new year break). I have a project to track people's
> daily trajectory pattern and then analyze it for city planning. Now the
> most difficult thing is how to get the trajectory datasets. One simple
> way would be to collaborate with cell phone operators, and ask them to
> release all trajectories in one particular geographic area. But it seems
> difficult, simply phone company would not cooperate if there is no
> direct benefit. Another way would be to invite individual people to
> voluntarily participate, and asked them to send an SMS to individual
> respective phone operators to release the trajectory datasets. Anyone
> there had such an experience to share? Would the cell phone operators
> have such duty to do so? Many thanks in advance.
>
> Cheers.
>
> Bin
>
> SteveC wrote:
> > Tom Carden wrote:
> >
> >> feeds of live cab locations in San Francisco. I believe Google
> >> offers maps of the same for most US cities, but I don't know how
> >> accessible the data is.
> >
> > There's a hack for that in google maps hacks from oreilly.
> >
> > have fun,
> >
> > SteveC [log in to unmask] http://www.asklater.com/steve/
> >
>
>
> --
> --------------------------------------------------------
> Bin Jiang
> Division of Geomatics
> Dept. of Technology and Built Environment
> University of Gävle, SE-801 76 Gävle, Sweden
> Phone: +46-26-64 8901 Fax: +46-26-64 8828
> Email: [log in to unmask] Web: http://www.hig.se/~bjg/
> --------------------------------------------------------
>
> NordGISci: http://www.hig.se/~bjg/NordGISci/
> NordGISci2007: http://www.hig.se/~bjg/NordGISci2007/
> ICA Workshop: http://www.ggy.uga.edu/people/faculty/xyao/Workshop2007/
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