[GRASSLIST:957] Re: live GRASS/GPS interface

[Buchan Milne]

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Hamish wrote:
> I've been thinking about how to do a real-time GRASS/GPS interface.
>
> General idea is to have a GPS feeding NMEA statements into the laptop's
> serial port, and have a program running in the background which parses
> the statement, feeds it through PROJ, and appends the result into a
> site_lists/gps_track file, as well as replacing the single point in a
> site_lists/latest_postion sites file. Lat-Lon, Time, COG, SOG, other GPS
> messages would be written to the site's comments. (or even run r.what
> for that position and use that in the comment string)
>
> e.g.:
>
> d.rast topo
> d.vect contours
> d.sites gps_track color=red size=1
> d.sites latest_position color=red size=3
> d.site.labels latest_position attr=...
>
> then, d.redraw or d.pan should update the track whenever I update the
> monitor.
>
> I suppose you could also have a background process which runs:
> g.region sites=latest_postion
> d.redraw
> every few minutes if you wanted. It could even do a little math so it
> only redraws when latest_postion is outside WIND ...
> I suppose a 5.1-style GUI could be written to control all this..
>
>
> Not very clean, but I think it should work.
>
> I've already written the NMEA parser, output to the sites format is
> trivial, but I'm not sure about how to go about the serial port daemon
> (although I am pretty familiar with RS232 i/o).
>
>

I have been doing some similar stuff (not directly to grass, I need some
ohter processing first), and found it convenient to make a gpsd client.
This allows the use of a remote GPS, or a local GPS, and allows you to
forget about managing the serial port, and also allows multiple programs
to access the data.

Regards,
Buchan

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Buchan Milne                Mechanical Engineer, Network Manager
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