[Qgis-user] connect the dots

Germán Carrillo carrillo.german at gmail.com
Wed Nov 11 16:23:42 PST 2009


Hi all.

I think would be great not only allow an "index" field with the points order
in the line, but also an "route" field (or "line" field, or "feature" field)
whith the line id. This way can be possible create a new layer with several
lines from a point layer.

Regards.

Germán

2009/11/11 Declan Troy <declan.troy at gmail.com>

> Hey Giovanni et al.,
>
> Yup, you correctly described the situation, a series of points with
> associated times that I want to link in order. Should be pretty
> straightforward.  The birds I track like to complicate things a bit by
> weaving back and forth across 180° but that is a side issue.
>
> An ideal project to learn python scripting on but I'll hedge my bets and
> send Richard a sample data set on the odds that his group will get to it
> faster than I will (thanks Richard).
>
> And thank you Brendan for the PostGIS example. PostGIS is also on the list
> of things to delve into but a bit further down the list to learn. The
> simplicity of the solution makes another case for trying to get there sooner
> than later.
>
> Thanks for the interest and responses to my query.
>
> Declan
>
>
>
> On Nov 10, 2009, at 12:10 PM, G. Allegri wrote:
>
>  Hi Declan,
>> I had the same need some time ago, but than I decided to follow
>> different ways in my analysis so I didn't went on on with this. You're
>> talking about migration paths, so I suppose you have temporal
>> attributes on your points, or some other kind of sequential index that
>> makes points logically connected. Right? In such case it wouldn't be
>> difficult with little scripting: just sort them on the index, and then
>> loop over their coordinates to build the polyline. It would a nice,
>> simple, exercise I think... or...am I making things too simple?
>>
>> bye,
>> giovanni
>>
>> 2009/11/10 Declan Troy <declan.troy at gmail.com>:
>>
>>> Hey Richard,
>>>
>>> Thanks for the response. Indeed fTools was the first place I looked as it
>>> seemed the type of functionality that might be there. Perhaps some day,
>>> or
>>> maybe in the rumored Ecological toolbox?
>>>
>>> Seemed like the type of operation that many users might have cause to use
>>> so
>>> I was hoping there was an easy way I was just overlooking but perhaps I
>>> misjudged. Once I get around to learning to write python plugins this
>>> should
>>> be a nice project to start on. Until then I can do this outside of QGIS,
>>> I'm
>>> just periodically attempting to see how far I can get in the hopes of
>>> shifting over. Each version keeps getting better.
>>>
>>> Declan
>>>
>>>
>>> On Nov 9, 2009, at 6:19 AM, Richard Duivenvoorde wrote:
>>>
>>>
>>>>  Is there a mean in QGIS to convert a series of points to a polyline?
>>>>> I would like to create some tracklines from series of telemetry
>>>>> points to summarize movement/migration paths. I hope I've overlooked
>>>>> something but the commands I see tend to be dissolution rather than
>>>>> aggregation of features.
>>>>>
>>>>
>>>> Hi Declan,
>>>>
>>>> don't know a tool like that (but I'm not authorative for that...), but
>>>> the
>>>> first thing I think of is the fTools-functionality of Carson Farmer (in
>>>> Vector menu of Qgis). It already does things like that. Maybe it's worth
>>>> a
>>>> feature request to him?
>>>>
>>>> Another option would be to write a python plugin for it? Or add it to
>>>> the
>>>> plugin-wishes list if you do not want to do it yourself:
>>>> http://www.qgis.org/wiki/Vector_Support_Wishes
>>>>
>>>> Regards,
>>>>
>>>> Richard Duivenvoorde
>>>>
>>>>
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