|
|
| (2 intermediate revisions by one user not shown) |
| Line 1: |
Line 1: |
| − | {{Content Tree|HEADER=QGIS Tutorial|NAME=QGIS tutorial}}
| + | #redirect[[GRASS region]] |
| − | | + | |
| − | | + | |
| − | {{typed|text=g.region}} is a very important module because it manages the boundary definitions for
| + | |
| − | geodata. Changing the settings means that you modify several parameters of a region:
| + | |
| − | * geographical projection (e.g. UTM, Latitude-Longitude, Gauss-Krueger, etc),
| + | |
| − | * geographical extension, i.e. the North/South/East/West limits of the area covered,
| + | |
| − | * number of columns and number of rows for the data,
| + | |
| − | * resolution, i.e. the extension divided by the number of rows (N-S resolution), respectively (E-W resolution).
| + | |
| − | | + | |
| − | How do we use it? One of several possibilies is to use the GRASS Shell. Open the Toolbox click on {{mitem|text=Modules List → GRASS Shell}}.
| + | |
| − | | + | |
| − | '''Synthax'''
| + | |
| − | *{{typed|text=g.region [rast=name ] [vect=name ] [res=value ] -p -l}}
| + | |
| − | '''Parameters'''
| + | |
| − | *{{typed|text=[rast=name]}}= Set region to match this raster map
| + | |
| − | *{{typed|text=[vect=name]}}= Set region to match this vector map
| + | |
| − | *{{typed|text=[res=value]}}= Grid resolution 2D (both north-south and east-west)
| + | |
| − | '''Flags'''
| + | |
| − | *{{typed|text=-p}}= Print the current region
| + | |
| − | *{{typed|text=-l}}= Print the current region in lat/long using the current ellipsoid/datum
| + | |
| − | | + | |
| − | '''Why care about the region?'''
| + | |
| − | | + | |
| − | The region defines the extension and geometric resolution (pixel size) of the data on
| + | |
| − | which most GRASS (raster) commands work. If the region is set to a smaller extension
| + | |
| − | than that of the map you are working on, display and results of raster processing
| + | |
| − | commands will only show the portion of the map that is contained in that region.
| + | |
| − | | + | |
| − | {{attention|text= In short, this means that whatever command you use in GRASS, it is always applied '''only to the data in the current region.''' So always keep an eye on the region settings!}}
| + | |
| − | | + | |
| − | ==Related articles==
| + | |
| − | * [[GRASS integration]]
| + | |
| − | * [[GRASS toolbox]]
| + | |
| − | * [[GRASS manual]]
| + | |
| − | * [[GRASS shell]]
| + | |
| − | * [[Region settings]]
| + | |
| − | * [[Creating a new location]]
| + | |
| − | * [[GRASS data import]]
| + | |
| − | | + | |
| − | | + | |
| − | [[category:Introduction to Quantum GIS]]
| + | |
