[Openstreetmap] geodriving results

Graham Wall g.hamwall at gmail.com
Fri Apr 8 21:08:49 BST 2005


A word of caution on accuracy and precision. I've written a little
about it here, with an example:
http://www.prizeonion.co.uk/?p=17

Basically - yes, the data looks like it's following a neat path, but
that path might be reported as being in the wrong place. It would be
interesting to see what happens if you repeat the same route.

It's a shame that the Garmin protocol and GPX have no provision for
the reported accuracy of a trackpoint, but repeated observations of
the same roads will give an indication of accuracy.

Graham

On Apr 6, 2005 9:11 PM, Alex Willmer <alex at moreati.org.uk> wrote:
> SteveC wrote:
> 
> >So the past weekend a few of us piled in to a hire car to take some
> >tracks.
> >
> >
> I've also gathered some tracks, they cover the part of the M1, the M6
> East of Birmingham, part of the M42, half of the M5 some streets in the
> North of Birmingham. Long distance stuff was gathered with a bluetooth
> receiver on the dashboard (even worked with heated front windscreen!)
> The streets in my immediate neighbourhood were by bike, receiver in bum bag.
> 
> The logging was performed by cotoGPS running on a Palm, extraction and
> conversion using pilot-xfer+cotoGPS Desktop on Linux. I've not captured
> any metadata. The GPX file is here:
> 
> http://www.alexwillmer.pwp.blueyonder.co.uk/track-trial-20050405aw.gpx.gz
> 
> Observations:
> 
> - GPS accuracy is amazing, there's clear seperation where I doubled
> back, even on narrow streets. For what ever map is produced by us, it's
> clear wide roads and up will need capturing in both directions.
> 
> - Capture will have to be systematic for local roads, major roads and
> motorways are few enough we could capture them in the course of travelling.
> 
> - As a simple method of keeping track it would make sense to do the
> edges (major throughfares) and use them as a structure to define areas
> that can be marked todo -> done.
> 
> - Simple algorythm for doing an area systematically: keep turning left
> unless you've done that bit.
> 
> - For me at least, GPS batteries last much longer than PDA or laptop
> batteries - use an adaptor
> 
> - It would be very useful to have a dictation program, audio notes
> timestamped to the GPS.
> 
> - Capturing local roads by bike is effective for getting
> urban-residential raw data, quite relaxing infact.
> 
> Questions:
> - Following the SCO and *Alexis de Tocqueville *claims regarding Linux,
> can we anticipate claims of copyright infringement?
> - If so, what raw data and documentation (gpx files, notes, diaries,
> sketches, audio, photos) should be kept to prove clean room
> reimplementation?
> - What data, if any, can we avoid gathering on the ground (eg points of
> interest, street names, road designations, urban/rural land designation)?
> - What data is available, if any, regarding organisational boundries
> such as counties and boroughs?
> - By what standard do we judge a road/track as a public road - ie I took
> the rule of thumb 'follow the curb, if it's marked private or it's just
> for parking, don't go there', is that sufficient?
> - Anyone else doing this in the Birmingham area?
> 
> 
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