GPS based data acquisition?

[Richard Weait]

On Wed, May 26, 2010 at 11:31 AM,  <phiscock-g851W1bGYuGnS0EtXVNi6w at public.gmane.org> wrote:
> Now I need to figure out how that data could be superimposed on a map...

Well, why didn't you say so!  ;-)

It you use .gpx to store your track file it is trivial to display that
gpx track over your map of choice.  Lots of software can read gpx and
display it with your choice of basemap.  There are a dozen or so Open
Source GIS packages to consider.  Try OpenJUMP if you don't have a
favorite already.    Here is a quick way to even display that track
over OpenStreetMap on your web site.

http://weait.com/content/easy-osm-your-gpx-tracks

This just shows the track.  Let's talk about showing the data.

One of the OpenStreetMap editors, josm[1], will display gpx tracks,
and vary the track colour by the velocity.  Not quite what you want,
but perhaps you can hack the code, or write a josm plugin to look in
the gpx for an arbitrary data tag, and convert that to colour or
intensity for display?

If you are primarily interested in showing the data on a web site,
perhaps dive back in to OpenLayers[2] which is pretty much a magic
wand for maps on web sites.  One gentleman recently demonstrated heat
maps in OpenLayers[3]. That code hasn't been released yet, as  far as
I know, but that might be a good start for your illumination data.

If all of this doesn't really seem right for you then you could
consider one of the heavy-duty map generation stacks.  Perhaps use
mapnik[4] to generate a set of translucent light-pollution tiles from
your collected data, then use OpenLayers to display the data over your
favourite base map. The Hike/Bike map is an excellent example of this
method.  [5] That link has the translucent "by night" layer active.
Press the blue plus sign (top right) to enable / disable the "by
night" or hill shading layers to see how your data might look over
your map.  Generating those translucent tiles is a slightly bigger
deal, but you get the chance to change rendering by zoom level which
will make your data look great at city, or street scale.

Sounds like tons of fun.

[1] http://josm.openstreetmap.de
[2] http://openlayers.org
[3] http://opengeodata.org/osm-heatmaps-in-the-browser-w-openlayers
[4] http://mapnik.org
[5] http://hikebikemap.de/?zoom=12&lat=50.93563&lon=14.15823&layers=B0000TFTFF
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