[OSM-newbies] Will the real track please step forward
christof at infinitus.co.uk
Mon Mar 26 00:27:51 BST 2007
I'm glad I'm not the only person experiencing "oddities" with track results;
I drove around Birmingham for about two hours and got fairly expected
results - but at one point I got caught up in rush hour traffic, and the
resulting track whilst I was stuck in slow-moving queues is all over the
place! I have a Qstarz BT-Q880 (little oblong blue receiver, sits in the
palm of your hand nicely) fwiw.
Interestingly though, all my results seem to be (consistently) slightly
adrift when compared to the existing ways and paths... Any reason for this,
or any way to fix? I can post my raw .gpx conversions if anybody wants to
take a look for themselves. I'm currently wading about inside JOSM trying to
figure out how to correctly convert my results into properly-formatted data
to upload, but I've not submitted anything yet.
First post to the list, also. Hi all :)
> -----Original Message-----
> From: Dirk-Lüder Kreie [mailto:osm-list at deelkar.net]
> Sent: 26 March 2007 00:06
> To: digger vermont
> Cc: Open Street Maps
> Subject: Re: [OSM-newbies] Will the real track please step forward
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> digger vermont schrieb:
> > I have a few tracks I've made by walking around. They make me look
> > like a drunken sailor with the amazing ability to right
> through blocks
> > of buildings! I've another from driving that looks somewhat
> > It actually coincides for the most part with yahoo maps. Is this as
> > good as it gets?
> > I have made some nodes, segments, and ways but at this point I
> > hesitate to upload them because of the accuracy.
> The SirfStar III Chipset has problems in some situations when
> you walk with it, because it trusts speed measurements more
> than position measurements apparently.
> Disclaimer: I have no real knowledge about how the SirfStar
> III does stuff internally, this is based solely upon my own
> observations of the behaviour and some knowledge about GPS
> measurements in general.
> Due to the nature of the sampling inside the GPS receiver it
> detects the diverse movements of the walking body and
> extrapolates its next positions from it, when the positional
> data is not accurate enough (only
> 3 sats or bad reception) it even "drifts" in that direction
> for a bit longer than strictly needed, thus generating these
> "drunken sailor" tracks.
> You'll find that putting the GPS receiver on your back or
> shoulder and cycling to be much more accurate than walking,
> because the speed measurements and the repeated location
> samples can work together.
> Dirk-Lüder "Deelkar" Kreie
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