Daniel - Thanks! (Remind myself to re-read the manual for the functions
I don't often use!)
Richard
Daniel Victoria wrote:
If I understand you correctly, v.hull might help to create the service
area polygon from the points....
http://grass.itc.it/grass62/manuals/html62_user/v.hull.html
On Sun, Apr 4, 2010 at 8:12 PM, Richard Chirgwin
<[email protected]> wrote:
------------------------------
Message: 3
Date: Sat, 03 Apr 2010 23:11:26 +0200
From: "Johannes Sommer" <[email protected]>
Subject: [GRASS-user] v.net.iso - service area
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
Hi list,
recently I played around with the network functionality in ArcGIS. I
generated so called "Service Areas" in a network dataset which return the
regions that can be accessed in a network dataset based on several distances
(in my example 150, 400 meters).
I wanted to reproduce the results with GRASS GIS and after a short search
I found the module v.net.iso which seemed to fit my needs. It returns
exactly the same results as ArcGIS did on isolines on a network, but I can't
find any solution concerning the service areas.
Can anyone point me in the right direction to calculate zones (that is
"build polygons from the end points of each network segment") from these
generated isolines in a network?
Regards,
Johannes
Johannes,
I don't think there's anything to do this automatically in Grass-GIS. But I
think you should be able to construct a script that would connect pairs of
points.
So if you can extract each end point of the network segment, you would end
up with a vector containing only points - then create a temporary map of a
point pair, run (say) v.distance output=connectors on each point pair, patch
the resulting maps together ...
It sounds a bit labourious, and probably someone else can think of something
easier, but if you get all the individual steps right, a script is then easy
to create.
(Actually, Johannes, I think the idea is brilliant. I've done lots of
network service area work, and it never occurred to me before!)
Richard Chirgwin
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