[GRASSLIST:955] live GRASS/GPS interface

[Hamish]

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).


Anybody have thoughts or suggestions before I dive into the gpsdrive
code?


Hamish