[GRASSLIST:2425] Re: g.region output in decimal degrees

[Markus Neteler]

On Sun, Feb 01, 2004 at 12:16:02AM -0500, Jason Horn wrote:
> Small but perplexing question:
> 
> g.region outputs the coordinates of a lat-lon locaion in dd:mm:ss
> format.  How can I get it into decimal degrees?  (I can't just convert
> it manually - I'll loose accuracy.)  I need to know the exact
> boundaries of the region in decimal degrees.  In the manual page for
> g.region, it shows output for g.region -l in decimal degrees.  But I
> get dd:mm:ss when I invoke it.


In a latlog location:

GRASS 5.7.-cvs:~ > g.region -p
projection: 3 (Latitude-Longitude)
zone:       0
datum:      wgs84
ellipsoid:  a=6378137 es=0.00669438
north:      47:39:27.3456N
south:      47:27:03.6432N
west:       10:56:05.2476E
east:       11:04:23.0484E
nsres:      0:00:02.9988
ewres:      0:00:02.9988
rows:       248
cols:       166
GRASS 5.7.-cvs:~ > g.region -g
n=47.657596
s=47.451012
w=10.934791
e=11.073069
nsres=0.000833
ewres=0.000833

In a Gauss-Krueger (Transverse Mercator) location:
GRASS 5.7.-cvs:~ > g.region -p
projection: 99 (Transverse Mercator)
zone:       0
datum:      potsdam
ellipsoid:  bessel
north:      5956600
south:      5953200
west:       3380000
east:       3382000
nsres:      0.32
ewres:      0.32
rows:       10625
cols:       6250
GRASS 5.7.-cvs:~ > g.region -l
long: 7.18156 lat: 53.72834 (north/west corner)
long: 7.21185 lat: 53.72880 (north/east corner)
long: 7.21314 lat: 53.69826 (south/east corner)
long: 7.18288 lat: 53.69780 (south/west corner)
rows:       10625
cols:       6250
Center Longitude: 7:11:50.484819E [7.19736]
Center latitude:  53:42:47.876333N [53.71330]

To be disussed is which datum 'g.region -l' should use. Maybe the
code should be updated to work as 'd.where' does:

  -d   Output lat/long in decimal degree
  -l   Output lat/long referenced to current ellipsoid
  -w   Output lat/long referenced to WGS84 ellipsoid using datum

Markus Neteler