[GRASS-user] v.net.iso - service area

[Daniel Victoria]

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
<rchirgwin at ozemail.com.au> wrote:
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Sat, 03 Apr 2010 23:11:26 +0200
>> From: "Johannes Sommer" <Johann.online at gmx.de>
>> Subject: [GRASS-user] v.net.iso - service area
>> To: grass-user at lists.osgeo.org
>> Message-ID: <20100403211126.313360 at gmx.net>
>> 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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