[ gpsdrive ] External program interfacing with gpsdrive

[Hamish]

Stan:
> Could do with a hand on the data, for something called 'well known text'

Well Known Text (more commonly seen as "WKT") is a standardized way to
talk about map projections across spoken languages and regions.

for example, for Lat/Lon WGS84 like your GPS reports the WKT is:

GEOGCS["wgs84",
    DATUM["WGS_1984",
        SPHEROID["WGS_1984",6378137,298.257223563],
        TOWGS84[0.000,0.000,0.000]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433]]


hey, there's even a wikipedia article for it:
  http://en.wikipedia.org/wiki/Well_Known_Text


> its proving a real pain to find what the decimal data refers to, any
> pointer to some info on how it converts?

can you provide more specifics about the data? short example?


> I'm guessing there is something in the gpsdrive 
> source but I couldn't see it.

the PROJ.4 library and probably GDAL contain code to translate between
WKT, PROJ.4 parameter format, and EPSG codes (e.g. LL/WGS84 is
EPSG # 4326). I would say that EPSG code is preferable as there is
even less doubt about which projection+datum is being referred too.


> Sticking with libgda for data access and it looks like the

(you mean libgdal ?)

> grass libs should be good for the routing but thats a long way off at
> the mo.

well, get stuff running one step at a time. I think GRASS is a nice
stepping stone to work up a prototype for the routing as the support
modules are already there and working, but in the long run dglib (if
used) could be used a la carte without the full GRASS dependency.

note GRASS uses GDAL as its primary non-native data I/O provider; they
complement rather than compete. I did not mean to imply otherwise.


stuff to play with,
Hamish