[GRASS-user] Strange behaviour of v.net on GRASS GIS 7

[Lluís Vicens]

On 28/08/14 22:56, Markus Metz wrote:
> On Thu, Jul 3, 2014 at 1:32 PM, Lluís Vicens <lluis at sigte.udg.es> wrote:
>> Hi,
>>
>> I'm working with GRASS GIS 7.0.0svn (r59969) on Ubuntu 14.04 LTS and I'm
>> experiencing a strange behaviour when using v.net. I have set of nodes that
>> I want to connect to a collection of streets on a network.
>>
>> When I execute "v.net streets points=poi out=net op=connect thresh=35" on
>> GRASS GIS 6.4.4, the new arc(s)/line(s) that connect the points to the
>> network, inherit all the attributes (even the 'cat' value) of the
>> pre-existing arcs. But, when I execute the same command on GRASS GIS 7.0.0
>> that expected behaviour doesn't take place. The new arc(s)/line(s) generated
>> with GRASS 7 doesn't have attributes, a new cat value is generated for each
>> new line but they doesn't appear on the attribute table...
>>
>> I don't know if this is a bug/error, or a different but deliberated
>> behaviour.
> This new behaviour is by purpose. It does not make sense for a new arc
> to inherit the category and attributes of a pre-existing arc. For
> example connecting a point to a one-way road could cause the point to
> become unreachable because the new arc would also be a one-way road.
> If a pre-existing arc is split into two parts, the two new components
> should inherit the attributes, but not the categories in order to be
> able to assign unique costs to the arcs. See the manual for v.net.path
> for an example.
>
> Unless you want to do something particular with these new arcs, it is
> usually easier to snap the points to the network instead of creating
> new arcs from the points to the network (GRASS 7 only).
>
> Markus M

A lot of thanks Markus, for your answer and explanation.
Cheers,

Lluís
>
>> Thanks in advance.
>> Cheers,
>> Lluís
>>
>> --
>> Lluís Vicens
>>
>> SIGTE - Universitat de Girona
>> Pl. Ferrater Mora, 1
>> 17071   Girona
>>
>>
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-- 
Lluís Vicens

SIGTE - Universitat de Girona
Pl. Ferrater Mora, 1
17071   Girona

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