[HOT] experience and methodology

Peter Wendorff wendorff at uni-paderborn.de
Wed Dec 21 10:06:13 GMT 2011


Hi Frans.

In OSM in generally it's not a good advise to take GPS logs from the 
device directly to push it into the map database.
But: Use your human mind to fix the measurement errors: a straight road 
is a straight road, even if the trace says it's a zig-zag-line crossing 
the straight connection repeatingly.

You ALWAYS have to do this manual postprocessing of traces, and that's 
not due to your specific logging device.

Good strategies are:
- trace more than one log of the same route and manually use some kind 
of average over all.
- trace intersections not by stopping in the middle and marking a 
waypoint, but by crossing the intersection in both directions to get 
crossing lines in the trace later.
- for fix points (like post-boxes, drinking water supply...) place the 
device on top of it and measore for a while (some minutes). You'll again 
get a blurred blob in the gpx trace with the jumping signal: use the 
middle (and justify the whole stuff with roads etc).

regards
Peter

P.S.: Always keep in mind: relatively accurancy of the whole map - and 
between the map features - is better than absolute accurancy of a few 
elements, but post boxes mapped on the wrong side of the street.

Am 21.12.2011 09:59, schrieb Frans Thamura:
>
> We use gps essential, and we got that waypoint is.not ideal to map, we 
> need extra effort.
>
> That is. We need your wxperience work with bad way point to become 
> high quality map
>
> On Dec 21, 2011 3:19 PM, "Kate Chapman" <kate at maploser.com 
> <mailto:kate at maploser.com>> wrote:
>
>     Hi Frans,
>
>     What do you mean by experience before and after?  The differences in
>     the data? What people learned?
>
>     What is available at: http://tasks.hotosm.org/job/9 is the
>     instructions we gave people.
>
>     There wasn't any data available beforehand except a couple roads.
>
>     -Kate
>
>     On Wed, Dec 21, 2011 at 2:49 PM, Frans Thamura <frans at meruvian.org
>     <mailto:frans at meruvian.org>> wrote:
>     > hi all
>     >
>     > read about mapping in padang etc,
>     >
>     > can anyone share your experience, from before to after.
>     >
>     > so we can see the different of the valuable work.
>     >
>     >
>     > --
>     > Frans Thamura (???)
>     > Shadow Master and Lead Investor
>     > Meruvian.
>     > Integrated Hypermedia Java Solution Provider.
>     >
>     > Mobile: +628557888699 <tel:%2B628557888699>
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>     >
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>     > Website: http://www.meruvian.org
>     >
>     > "We grow because we share the same belief."
>     >
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