You might want to consider a different idea: convert the line vector to
a raster, then apply the r.grow.distance module to "fill" all null
pixels in between the line pixels with the cat value of the closest line.
Here's how it would work in the nc_basic_spm mapset, using the 'streams'
vector:
g.mapset -p
#user1
g.region -ap rast=elevation
g.copy vect=streams,mystreams
v.to.rast mystreams output=streams_rast use=cat
r.grow.distance input=streams_rast value=theissen_areas
r.to.vect -s theissen_areas output=theissen_polys type=area
Here is what the result looks like:
https://pasteboard.co/IXYLwGI.png
HTH, Micha
On 3/7/20 1:16 AM, karsten wrote:
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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Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918
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