[Openstreetmap] Open Map of Paris

Lars Aronsson lars at aronsson.se
Fri Jun 17 22:04:21 BST 2005


Karen O'Rourke wrote:
> What does the GPS unit need to be able to do? I gather there are problems of
> reception, storage and compatibility. Do you have any concrete suggestions
> on which models might be better for this kind of project? We need some kind
> of receiver which can be connected to a PC. There is no need to buy any kind
> of map data if we're generating our own, or is there?

I bought a Garmin Foretrex 201 which I carry in a welcro band 
around my wrist, just like a (big) watch.  This means I can bring 
it everywhere I go: walking, running, bicycling or by train.  In 
my car, I have taped a welcro strip to the front of my dashboard, 
where I put it when I drive.  I'm very happy with this solution. 

This unit stores up to 10,000 track log points, which is more than 
enough. It can be set to a fixed time interval (1, 2, 3, ... 
seconds), fixed distance interval (every 50 meters or so) or 
"automatic", which means the unit only stores your position and 
timestamp when you change speed or direction.  The automatic 
setting is the most economic, and contains all the information you 
should need.  However, the current implementation of the 
OpenStreetMap.org website works best with the fixed time interval.  
I wrote a comment about this on my user page in the wiki, 
http://www.openstreetmap.org/wiki/index.php/User:LA2

> I've been looking into GPS & have found some lists of waypoints 
> online (http://www.swopnet.com/waypoints/gps/france5.html). Can 
> these be used/useful to the project?

In theory they should be.  However, I don't know if they can be 
used in the current website implementation.

When you shop for a GPS receiver, you will find in the technical 
specifications and sales brochures that most GPS receivers handle 
various quantities of three kinds of data: waypoints, routes, and 
track logs. Track logs are recordings of where you have been, and 
typically function in the way described above. Waypoints are 
important points of interest or destinations, such as restaurants, 
gas stations, traffic speed cameras, your home, or where in the 
parking lot you left your car.  Routes are sequences of waypoints 
that you plan to visit.  The typical GPS receiver allows you to 
navigate towards a given waypoint or leg of a route.  It will tell 
you the direction and distance towards your next destination. More 
advanced GPS receivers can store maps that contain information on 
one-way-streets for more advanced navigation.  More simple units 
such as the Garmin Foretrex 201 cannot store maps.


-- 
  Lars Aronsson (lars at aronsson.se)
  Aronsson Datateknik - http://aronsson.se




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