Re: [OSGeo-Discuss] geospatial algorithm to create area midway boundaries from lines ?

2020-03-06 Thread Markus Neteler 
Hi Karsten,

With v.type you can then change the type "line" to "boundary" and
eventually place centroid(s) with v.centroid to complete closed boundaries
plus centroid to topologically correct areas.

Best,
Markus

karsten  schrieb am Fr., 6. März 2020, 18:28:

> Hi Markus,
>
> I will look into this Grass function and how I can use it. I am not sure
> however if it can output polygons rather than lines
>
> Cheers
> Karsten
>
> --
> *From:* Markus Neteler [mailto:nete...@osgeo.org]
> *Sent:* Friday, March 06, 2020 14:55
> *To:* karsten
> *Cc:* OSGeo-discuss
> *Subject:* Re: [OSGeo-Discuss] geospatial algorithm to create area midway
> boundaries from lines ?
>
> Hi Karsten,
>
> Probably this GRASS GIS Addon can help:
>
> https://grass.osgeo.org/grass7/manuals/addons/v.centerline.html
>
> If I got your wish right...
>
> Best,
> Markus
>
>
> karsten  schrieb am Fr., 6. März 2020, 17:36:
>
>> Hi All,
>>
>> a general geospatial question to all:
>> I am trying to find out if there is any existing geospatial algorithm (in
>> any open Open Source Geospatial software) that would allow to use a network
>> of lines as a start point and expand those in such a way that I can create
>> new area boundaries for each of the lines "coverage area". What I mean with
>> that is if one could "buffer" the lines out in such a way to create
>> boundaries where any potential buffers would meet at the middle way point
>> between the lines so that in the end I could have an area within that is
>> the starting line. On example could look like this (5 hand drawn lines in
>> red and corresponding colored areas that I would want to create). Note that
>> is exact but to communicate the idea) see
>> http://terra5.terragis.net/sites/html/aeras_for_lines%20copy.png
>>
>> It's kind of similar to Thiessen polygons but for lines instead of
>> points...
>>
>> One preference would be if there was something that could be used
>> programmatically on large data sets ...
>>
>> Cheers
>> Karsten
>>
>> Karsten Vennemann
>> www.terragis.net
>>
>> ___
>> Discuss mailing list
>> Discuss@lists.osgeo.org
>> https://lists.osgeo.org/mailman/listinfo/discuss
>
>
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Re: [OSGeo-Discuss] geospatial algorithm to create area midway boundaries from lines ?

2020-03-06 Thread karsten 
Hi Markus,
 
I will look into this Grass function and how I can use it. I am not sure
however if it can output polygons rather than lines 
 
Cheers
Karsten 

  _  

From: Markus Neteler [mailto:nete...@osgeo.org] 
Sent: Friday, March 06, 2020 14:55
To: karsten
Cc: OSGeo-discuss
Subject: Re: [OSGeo-Discuss] geospatial algorithm to create area midway
boundaries from lines ?


Hi Karsten, 

Probably this GRASS GIS Addon can help:

https://grass.osgeo.org/grass7/manuals/addons/v.centerline.html


If I got your wish right...

Best,
Markus


karsten  schrieb am Fr., 6. März 2020, 17:36:



Hi All,
 
a general geospatial question to all: 
I am trying to find out if there is any existing geospatial algorithm (in
any open Open Source Geospatial software) that would allow to use a network
of lines as a start point and expand those in such a way that I can create
new area boundaries for each of the lines "coverage area". What I mean with
that is if one could "buffer" the lines out in such a way to create
boundaries where any potential buffers would meet at the middle way point
between the lines so that in the end I could have an area within that is the
starting line. On example could look like this (5 hand drawn lines in red
and corresponding colored areas that I would want to create). Note that is
exact but to communicate the idea) see
http://terra5.terragis.net/sites/html/aeras_for_lines%20copy.png
 
It's kind of similar to Thiessen polygons but for lines instead of points...
 
One preference would be if there was something that could be used
programmatically on large data sets ...
 
Cheers
Karsten
 
Karsten Vennemann
  www.terragis.net
 
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Re: [OSGeo-Discuss] geospatial algorithm to create area midway boundaries from lines ?

2020-03-06 Thread karsten 
Hi Pierre,

I mean line segments like e.g. in a road or water GIS layer and they could
be smooth or rather less smooth.
The output I desire should be polygons and not lines. Overall I am looking
for nothing exact here - any approximate interpolation about midway
plus/minus would be fine...

Karsten

-Original Message-
From: Pierre Abbat [mailto:p...@bezitopo.org] 
Sent: Friday, March 06, 2020 14:59
To: discuss@lists.osgeo.org
Cc: karsten
Subject: Re: [OSGeo-Discuss] geospatial algorithm to create area midway
boundaries from lines ?

On Friday, 6 March 2020 17:36:15 EST karsten wrote:
> Hi All,
> 
> a general geospatial question to all:
> I am trying to find out if there is any existing geospatial algorithm 
> (in any open Open Source Geospatial software) that would allow to use 
> a network of lines as a start point and expand those in such a way 
> that I can create new area boundaries for each of the lines "coverage 
> area". What I mean with that is if one could "buffer" the lines out in 
> such a way to create boundaries where any potential buffers would meet 
> at the middle way point between the lines so that in the end I could 
> have an area within that is the starting line. On example could look 
> like this (5 hand drawn lines in red and corresponding colored areas 
> that I would want to create). Note that is exact but to communicate 
> the idea) see 
> http://terra5.terragis.net/sites/html/aeras_for_lines%20copy.png

When you say "lines", do you mean polylines made of line segments, polyarcs,
or polyspirals? If polyarcs, will they generally be smooth? If polyspirals,
will adjacent spiralarcs osculate, just be tangent, or neither?

What sort of lines would the output be? If the input is polyarcs, the output
could contain pieces of hyperbola. If the input is polyspirals, the output
could contain strange indescribable curves. The only curves used as land
boundaries are line segments and circular arcs, so they'd have to be
approximated.

Pierre
--
When a barnacle settles down, its brain disintegrates.
Já não percebe nada, já não percebe nada.




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Re: [OSGeo-Discuss] geospatial algorithm to create area midway boundaries from lines ?

2020-03-06 Thread Pierre Abbat 
On Friday, 6 March 2020 17:36:15 EST karsten wrote:
> Hi All,
> 
> a general geospatial question to all:
> I am trying to find out if there is any existing geospatial algorithm (in
> any open Open Source Geospatial software) that would allow to use a network
> of lines as a start point and expand those in such a way that I can create
> new area boundaries for each of the lines "coverage area". What I mean with
> that is if one could "buffer" the lines out in such a way to create
> boundaries where any potential buffers would meet at the middle way point
> between the lines so that in the end I could have an area within that is the
> starting line. On example could look like this (5 hand drawn lines in red
> and corresponding colored areas that I would want to create). Note that is
> exact but to communicate the idea) see
> http://terra5.terragis.net/sites/html/aeras_for_lines%20copy.png

When you say "lines", do you mean polylines made of line segments, polyarcs, 
or polyspirals? If polyarcs, will they generally be smooth? If polyspirals, 
will adjacent spiralarcs osculate, just be tangent, or neither?

What sort of lines would the output be? If the input is polyarcs, the output 
could contain pieces of hyperbola. If the input is polyspirals, the output 
could contain strange indescribable curves. The only curves used as land 
boundaries are line segments and circular arcs, so they'd have to be 
approximated.

Pierre
-- 
When a barnacle settles down, its brain disintegrates.
Já não percebe nada, já não percebe nada.



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Re: [OSGeo-Discuss] geospatial algorithm to create area midway boundaries from lines ?

2020-03-06 Thread Markus Neteler 
Hi Karsten,

Probably this GRASS GIS Addon can help:

https://grass.osgeo.org/grass7/manuals/addons/v.centerline.html

If I got your wish right...

Best,
Markus


karsten  schrieb am Fr., 6. März 2020, 17:36:

> Hi All,
>
> a general geospatial question to all:
> I am trying to find out if there is any existing geospatial algorithm (in
> any open Open Source Geospatial software) that would allow to use a network
> of lines as a start point and expand those in such a way that I can create
> new area boundaries for each of the lines "coverage area". What I mean with
> that is if one could "buffer" the lines out in such a way to create
> boundaries where any potential buffers would meet at the middle way point
> between the lines so that in the end I could have an area within that is
> the starting line. On example could look like this (5 hand drawn lines in
> red and corresponding colored areas that I would want to create). Note that
> is exact but to communicate the idea) see
> http://terra5.terragis.net/sites/html/aeras_for_lines%20copy.png
>
> It's kind of similar to Thiessen polygons but for lines instead of
> points...
>
> One preference would be if there was something that could be used
> programmatically on large data sets ...
>
> Cheers
> Karsten
>
> Karsten Vennemann
> www.terragis.net
>
> ___
> Discuss mailing list
> Discuss@lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/discuss
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[OSGeo-Discuss] geospatial algorithm to create area midway boundaries from lines ?

2020-03-06 Thread karsten 
Hi All,
 
a general geospatial question to all: 
I am trying to find out if there is any existing geospatial algorithm (in
any open Open Source Geospatial software) that would allow to use a network
of lines as a start point and expand those in such a way that I can create
new area boundaries for each of the lines "coverage area". What I mean with
that is if one could "buffer" the lines out in such a way to create
boundaries where any potential buffers would meet at the middle way point
between the lines so that in the end I could have an area within that is the
starting line. On example could look like this (5 hand drawn lines in red
and corresponding colored areas that I would want to create). Note that is
exact but to communicate the idea) see
http://terra5.terragis.net/sites/html/aeras_for_lines%20copy.png
 
It's kind of similar to Thiessen polygons but for lines instead of points...
 
One preference would be if there was something that could be used
programmatically on large data sets ...
 
Cheers
Karsten
 
Karsten Vennemann
  www.terragis.net
 
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