[OSM-talk] 68 GPS units donated to OSM

Erik Söderström erik at yi.se
Sun Jan 18 23:13:51 GMT 2009


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Gisle Sælensminde wrote:
> Chris Hill skrev:
>> But to push the average sample rate for an area up to a useful level you will need about a 100 trips on the same road - easy near a depot or a big customer, not so elsewhere.  It might give a reasonable track in very slow-moving traffic.
>>
>> Just uploading all the tracks to OSM and then looking at the combined download with JOSM will give you the average.  I think Potlatch joins the points together with a line which might be distracting when they are three minutes apart.
>>
>>   
> It may be that the way JOSM and potlatch work is not optimal for such
> data, so that they require extra processing. I do not think that you
> need 100 times coverage, and also this depends on the road. Since 3
> minutes is 180 seconds, this is equivalent to sampling every 1.8
> seconds, and in rural areas this is more than required. It is also not
> unlikely that one of many hundreds of cars pass a single road 100 times
> during a year, so I would still think that these data can be useful a
> lot more places than just outside a depot. For some rural roads it may
> take a very long time to get enough coverage, but eventually there will
> be coverage, since these data is collected every day of the year.
> 
> As mentioned, I can look at these data and see what can be done.
> 
> Gisle Sælensminde
> (email - gsale - broadpark - no)
> 
> 
I have sent the data to some fellow mappers in #osm.se (irc.oftc.net).
Its basically a CSV with lat/lon and time.

The file is at http://gamezone.fatal.se/~gem/pos.tar.gz

As I am VERY new to this, I'm not quite sure what to do with the data,
so perhaps you or anyone else can see if there is anything of value here.

http://sobek.yi.se/temporary/pos4_osm.jpg
is an example of overlaying gnuplot on an OSM map to see if there is
coverage. Scale of map and overlay is not equal, so the points dont
align properly with whats available.
You can view http://sobek.yi.se/temporary/pos4.jpg (which is a Google
map) for comparison.

// Erik
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