I use d.zoom to set the extents I want for the project mapset and see the
northern and eastern coordinates of this area. If I use g.region n=<values>
e=<values> res=30 I assume that the southern and western bounds will be
calculated as a round number of the resolution within the displayed window.
Is this correct?
If not, what is the preferred approach to interactively defining a region
and saving it as the default for that mapset?
Rich
On Wed, 27 Jul 2011, Rich Shepard wrote:
I use d.zoom to set the extents I want for the project mapset and see the
northern and eastern coordinates of this area. If I use g.region
n=<values> e=<values> res=30 I assume that the southern and western bounds
will be calculated as a round number of the resolution within the
displayed window. Is this correct?
Searching my saved mail list threads I found the answer: v.in.region
out=<region_name>. However, I have not found the follow up to this: now that
I have defined my limited analytical region, how do I clip the large maps
(and their associated attribute data) to this area?
For example, there are almost 805,000 stream/river reaches in the state
and many fewer in my area of interest; there are 4204 drainage basins
(12-digit resolution) in the state and only about 18 within my analysis
area.
What command deletes everything outside the current region?
Rich
On Wed, 27 Jul 2011, Rich Shepard wrote:
Searching my saved mail list threads I found the answer: v.in.region
out=<region_name>. However, I have not found the follow up to this: now
that I have defined my limited analytical region, how do I clip the large
maps (and their associated attribute data) to this area?
Well, that didn't work as expected. When I kill the monitor and start the
GUI I see only the bottom portion of the zoomed maps. Back to the drawing
board.
Rich
On Wed, 2011-07-27 at 10:13 -0700, Rich Shepard wrote:
On Wed, 27 Jul 2011, Rich Shepard wrote: > Searching my saved mail list threads I found the answer: v.in.region > out=<region_name>. However, I have not found the follow up to this: now > that I have defined my limited analytical region, how do I clip the large > maps (and their associated attribute data) to this area? Well, that didn't work as expected. When I kill the monitor and start the GUI I see only the bottom portion of the zoomed maps. Back to the drawing board.
First you’ll want to set your analytical region with g.region (use all four parameters, n-= s= e= w=. If you don’t specifiy any one of them, it will stay as it was.)
Now, for rasters, just run:
r.mapcalc =
Since r.mapcalc honors the current region, the new rasters will be limited to the new region
Next you can use the v.in.,region to get a rectangular vector of the current region, and use that with v.overlay to clip your various line and polygon vectors like:
v.overlay a_in=streams b_in=analytical_region_vector out=streams_clipped
v.overlay should merge all data columns into the resulting output vector.
–
Micha
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