Geography Reference
In-Depth Information
Usage:
v.proj [-lz] input=name location=string [mapset=string]
[dbase=string] [output=name] [--overwrite]
Flags:
-l
List vector files in input location and exit (a dummy value
must be given for input)
-z
(3-D vectors only) Assume z co-ordinate is ellipsoidal
height and transform if possible
--o
Force overwrite of output files
Parameters:
input
Name of input vector map
location
Location containing input vector map
mapset
Mapset containing input vector map
dbase
Path to GRASS database of input location
output
Name for output vector map
As you can see, there aren't many required parameters. You have to
know where the map resides, including the full path to the GRASS
database if it's in a different database than the target location. Usually
you get away with just entering the map name and location and speci-
fying the output name. As usual, GRASS gives you an --overwrite option
in case you need to run the command more than once to get it right.
We have a lakes map in our alaska_albers location that we can play with.
Let's project it to our UTM Zone 6 location alaska_utm6_nad27 . 1 We begin
by starting GRASS in the location where we want the projected map to
reside, in this case our UTM location, and then proceeding:
GRASS 6.3.cvs (alaska_utm6_nad27):~ > v.proj input=lakes \
location=alaska_albers mapset=PERMANENT output=lakes
Input Projection Parameters: +proj=aea +lat_1=55 +lat_2=65 +lat_0=50
+lon_0=-154 +x_0=0 +y_0=0 +no_defs +a=6378206.4 +rf=294.9786982
+nadgrids=/usr/local/grass-6.3.cvs/etc/nad/alaska
Input Unit Factor: 1
Output Projection Parameters: +proj=utm +zone=6 +a=6378206.4
+rf=294.9786982 +no_defs
+nadgrids=/usr/local/grass-6.3.cvs/etc/nad/alaska
Output Unit Factor: 1
Re-projecting vector map...
Building topology ...
177 primitives registered
Building areas:
100%
87 areas built
1. Projecting a region the size of Alaska into a single UTM zone is not really appropriate,
but it illustrates the process of projecting vectors with GRASS.
 
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