On Tue, Dec 29, 2009 at 12:01 AM, Liz ed...@billiau.net wrote:
There are many sources of error in SRTM and GPS and barometric height
measures.
First of all
Height compared to what?
WGS84 adjusted by the deviation between WGS84 and EGM96 at the lat/lon of
the measurement? Would that work?
the srtm contour data used in some osm renders is great, partic for
cyclists and walkers. i've realised that it's not as high
accuracy/precision as it might be though. i notice that most GPS
devices also record the elevation within their tracklogs, and that it
might be useful to extract this data,
Robin,
Robin Paulson wrote:
the srtm contour data used in some osm renders is great, partic for
cyclists and walkers. i've realised that it's not as high
accuracy/precision as it might be though. i notice that most GPS
devices also record the elevation within their tracklogs, and that it
2009/12/28 Frederik Ramm frede...@remote.org:
Pure GPS elevation is worthless due to bad precision (for technical reasons,
Z measurement is much worse than X/Y measurement in GPSes). Some GPSes have
ok, i didn't realise that. what levels of bad precision are we talking
about; i assume it varies
Hi,
Robin Paulson wrote:
ok, i didn't realise that. what levels of bad precision are we talking
about; i assume it varies form model to model; how does it compare to
the precision of srtm?
I'm not really an expert in this but Internet sources say that altitude
error is *at least* factor 1.5
: Frederik Ramm frede...@remote.org
Date: Tue, 29 Dec 2009 00:20:09
To: Robin Paulsonrobin.paul...@gmail.com
Cc: OSM Talktalk@openstreetmap.org
Subject: Re: [OSM-talk] augmenting contour data with gps track logs
Hi,
Robin Paulson wrote:
ok, i didn't realise that. what levels of bad precision are we
2009/12/28 Robin Paulson robin.paul...@gmail.com:
2009/12/28 Frederik Ramm frede...@remote.org:
Pure GPS elevation is worthless due to bad precision (for technical reasons,
Z measurement is much worse than X/Y measurement in GPSes). Some GPSes have
ok, i didn't realise that. what levels of
On Tue, 29 Dec 2009, Robin Paulson wrote:
the srtm contour data used in some osm renders is great, partic for
cyclists and walkers. i've realised that it's not as high
accuracy/precision as it might be though. i notice that most GPS
devices also record the elevation within their tracklogs, and
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