[GRASSLIST:2503] Re: Decimal degrees

[Rich Shepard]

On Wed, 26 Sep 2001, Eric G. Miller wrote:

> > We almost always use decimal degrees, with occasional use of degrees
> > and decimal minutes (NMEA format).

> > Is there any way to get grass to use decimal degrees?

> In what context?  Generally GRASS uses decimal degrees internally but
> reports or outputs coordinates as degrees:minutes:seconds<hemisphere>. The
> only way to change this behavior would be to hack the library code. --
> Specifically, src/libes/gis/wind_format.c -- No guarantee that'd be 100%
> successful, but probably would alter most cases to use decimal degrees for
> output.  Some modules might use the more specific routines found in
> ll_format.c, but modifying those would more likely lead to weird problems.

  This is a real problem for anyone taking data from a GPS for use in GRASS.
The NMEA message is in degrees/decimal minutes and, even if one wants to
convert the coordinate data to a projection, the software should accomodate
input in this format. Hmmm-m-m-m.

  I, too, face this problem with my bathymetric survey setup. For this I use
either of two GPS receivers (one sub-meter accuracy) and a depth-sounding
sonar. Both instruments feed into a notebook computer and I have a
time-stamped position plus a depth. The position from one GPS is only as
above, the other can be set to lat/lon, UTM or SPC.

Rich

Dr. Richard B. Shepard, President

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