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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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