steve at fractalus.com
Tue Oct 5 12:12:41 BST 2004
* Jono Bacon (jono at jonobacon.org) wrote:
> Hi Matt,
> >the primary form of any GPS data is going to be the track - raw lat,
> >long & time (altitude if we're lucky) which will be uploadable via a
> >java web applet and editable straight into the database.
> >current thinking regarding the actual map is that it won't come
> >straight from GPS, rather the track will be used as a sort of
> >"sketch" which will then be filled in by the user (or
> >already-existing roads selected).
> This sounds like an interesting idea, and a little different to how I
> initially envisaged community based mapping.
hi jono, sorry not to see you also at eurofoo :)
> I assume you folks have discussed the relative merits of using the GPS
> data to automatically plot the map as opposed to using it as a sketch.
> What do you feel makes the sketching option the better choice?
One person can take the map, and others can add road names and whatnot.
The idea is to seperate (to some extent) the geographical and the meta
data. For example, I might drive around... Sheffield and have a map but
no nothing about the street names, or not have the time to add them.
What I use can add notes to the data (more below).
The other reason is that gps is accurate enough to distinguish between
the two sides of the M6. For a first guess, one side might be ok but
then later someone else will go down the other side. If you have a
sketch with multiple tracks doesn the M6 (say one person goes in the
slow lane, another in the fast, another in the fast on the other side)
then you could either do one 'line' or perhaps both carriageways.
But this is all up for grabs if there are better ideas!
> Another option for either methods is to have a selection box in the GPS
> tool that allows the user to define what kind of surface they are
> travelling on. As an example, if they are going onto the M6, they would
> select Motorway. You could define all kinds of types of surface,
> including, but not limited to roads. You could also include paths,
> parks, private drives and various other types of information.
> Is it possible to create the map as some kind of vector based unit so
> that when you zoom in closer, you get more detail of the map? I have no
> idea how this would be done.
Me neither. IMHO expedia maps doesn't do this brilliantly well, in how
it chosses what to label at what zoom level.
> A few final questions:
> - What kind of database schema are you using for the database?
I'm still figuring out how to do this. Specifically the versioning
things, and how best to represent streets. I was looking at the free US
census road data sets and they have a pretty insane representation.
> - What tool are you using to actually store the GPS sketch before it is
I have an old laptop with two batteries, a USB gps and a wifi card. A
little java prog grabs the position every second off the gps (through
gpsdrives gpsd) and puts in mysql. then when I plug it in to the real
network I move all the sql data to the server. I have a zaurus to talk
wifi to the thing. with the zaurus you can add notes like street names
or postcodes or whatever, which get added to the map. The idea is to use
these notes to define streets....
SteveC steve at fractalus.com http://www.fractalus.com/steve/
More information about the talk