Geography Reference
In-Depth Information
• The coordinates of the area to become the default region and the
grid resolution of this region
• A short, one-line description or title for the location
We will be creating a worldwide location in geographic (latitude/longi-
tude) coordinates so we know the answer to all the questions. The sec-
ond requirement doesn't apply since we aren't using UTM or some other
projection. Pressing Enter brings us to the coordinate system selection
screen. The options are as follows:
• A x,y
• B Latitude-Longitude
• C UTM
• D Other Projection
Option B is what we want, so we press B and then Enter . If we had
specified one of the others, we would have had to enter additional infor-
mation that requires having some information about the projection and
its parameters. GRASS asks us to confirm our selection by entering Y
or just pressing Enter since yes is the default answer (indicated by the
brackets around “y” in the question):
Latitude-Longitude coordinate system? (y/n) [y]
GRASS now asks for a one-line description of the location. We'll use
something simple like “World wide location in latitude and longitude.”
After confirmation, we are asked whether we want to specify a datum.
This is always a good idea—in fact, it's essential to ensure your maps
are transformed properly should the need arise. For this location, we
will use WGS84. We also have to set a datum transformation parameter.
The transcript for this part of the process is as follows:
Please enter a one line description for location <world_lat_lon>
> World wide location in latitude and longitude
=====================================================
World wide location in latitude and longitude
=====================================================
ok? (y/n) [y]
Do you wish to specify a geodetic datum for this location?(y/n) [y] Y
Please specify datum name
Enter 'list' for the list of available datums
or 'custom' if you wish to enter custom parameters
Hit RETURN to cancel request
>WGS84
 
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