[Openstreetmap] Satellite cost/benefit

[Frank Mohr]

Jo Walsh wrote:
> > GPS collection
> could be 'sexy' in the right context: e.g. cyclist groups like the
> Tower Hamlets Wheelers of the Camden CC could love this; we could
> introduce a street scoreboard for cycle couriers; etc.

The map data (at least new data) for bbbike
(http://bbbike.sourceforge.net/)
is collected that way.

> 
> > using out of copyright data
> > ---------------------------
> > benefits: free, easy to obtain
> > costs: out of date data
> 

disadvantage: out-dated

Who long are maps copyrighted?

- I had a look at a german roadmap (1:500000) from 1955
  -> most "autobahn"-sections are missing.
  -> major roads have changed
- I compared the GPS data of my New-Years holidays with a 
  streetmap of Cologne from 1960 and a current streetmap
  -> streets were renamed
  -> inner city streets changed, some are now pedestian areas
  -> access roads to bridges changed
  -> most of the cathedral/station/rhine area changed
- Even if I compare a 1997 streetmap atlas (1:20000) with 
  my daily way to work
  -> 2 motorway interchanges had been modified
  -> a street crosses the office building i work in
  -> some industrial areas are missing or have changed
  -> several intersection changed to traffic circles
  -> in my (small) hometown, 2 development areas that 
     started that time are missing

> Schuyler's played with the
> douglas-peucker line simplication technique and got interesting if not
> totally convincing results. even a GPS layer would be a place to start
> tracing...

I'm still working on a algorithm to do some track-bundle averaging.

Frank