[OSM-dev] gpx elevation data for given bounding box?

[Robert (Jamie) Munro]

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Timo Juhani Lindfors wrote:
> Hi,
> 
> http://www.openstreetmap.org/api/0.5/trackpoints?bbox=24.910183149172653,60.15440288678513,24.95553022602672,60.17696276708048&page=0
> 
> gives me GPX data for a given bounding box but does not seem to
> include elevation data for any of the points. However, if I download
> the original GPX tracks from e.g.
> 
> http://www.openstreetmap.org/trace/185458/data
> 
> I can see elevation data. Is there anything I could do to get such
> elevation data for only specific bounding box? I am not sure how much
> www.openstreetmap.org likes if I download all GPX files (44 gigabytes
> if my extrapolation is correct) separately and then do bounding box
> filtering locally.

It would be interesting to get this data and compare it to STRM in areas
with a lot of traces, for example e-courier or ASTL datasets, which are
lots of vehicles regularly covering the same area. If you average real
data together, how close does it get? I know that theory says that the
results may not be very good, it would be good to see some results in
practise.

I also notice that sometimes if I my GPS starts off reading 20m to the
north of reality, the whole trace is 20m north of reality for a long
time, but the actual shape of the trace matches the road. I wonder if
vertical traces are the same - perhaps a GPS will consistently read 10m
above reality, and if we can correct for that where a trace overlaps
another trace or SRTM data, we can use it to fill in an SRTM void that
the trace continues into.

Robert (Jamie) Munro
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