[GRASS-dev] G7: v.mkhexgrid addon for hexagon creation

Markus Metz markus.metz.giswork at gmail.com
Thu Nov 20 00:52:46 PST 2014

On Thu, Nov 20, 2014 at 12:29 AM, Markus Neteler <neteler at osgeo.org> wrote:
> Hi,
> I have added v.mkhexgrid as new G7 addon to the Addons repo. The
> original author is Trevor Wiens who already implemented it as a Python
> script. I made some minor changes to get it running in GRASS GIS 7.
> Screenshot:
> https://svn.osgeo.org/grass/grass-addons/grass7/vector/v.mkhexgrid/v_mkhexgrid.png
> Originally I had hoped that v.voronoi would do the job but it does not
> create proper hexagons. I was running:
> # desired result:
> http://blogs.esri.com/esri/arcgis/files/2013/05/fig3.png (3rd figure
> within)
> # create first set of points
> g.region rast=elevation -p
> v.mkgrid -p map=pointpattern1 grid=13,15 position=region breaks=1
> # shift grid by half point distance
> g.region n=n+500 w=w+500 e=e+500 s=s+500 -p
> # create second set of points
> v.mkgrid -p map=pointpattern2 grid=13,15 position=region breaks=1
> # merge into final point pattern
> v.patch input=pointpattern1,pointpattern2 output=pointpattern3
> # generate Thiessen, hoping for hexagons
> v.voronoi input=pointpattern3 out=hexagon_attempt
> # show result
> d.mon wx0
> sleep 5
> d.vect hexagon_attempt type=boundary

The points are not "cleverly spaced". Attached is a python script that
generates center points of hexagons. The output of v.voronoi shows now

Markus M
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