[GRASS-dev] v.voronoi producing wrong output

[Cev Hillan]

Hello all,

As it is my first mail on this list, I would like to thank the devs and 
the whole team for the great work done in GRASS.

Before filing up a bug report I would like your advice on the following 
problem : the output of v.voronoi is wrong (additionnal lines and/or 
holes) for a set of around 4600 points in EPSG:27572 (in meters).

These are the steps to reproduce the bug :
v.in.ogr --overwrite input=C:\XXXX\points.shp output=points
g.region -p vect=points n=n+100 s=s-100 e=e+100 w=w-100 res=0.01 -a
v.voronoi --overwrite --verbose input=points output=voronoi_areas

The dataset is linked to the email, it is in EPSG:27572.
You will also find a picture of the (wrong) output.

The output of voronoi command is :
Reading features...
WARNING: La couche vectorielle <voronoi_areas> existe déjà et va être écrasé
Utilisation du format natif
Voronoi triangulation for 4622 points...
Writing edges...
Writing features...
Writing attributes...
Searching for topology errors...
WARNING: Le nombre de centroïdes dépasse le nombre de surfaces : 4622 > 3478
WARNING: Nombre de contours incorrects: 5058
WARNING: Nombre de centroïdes en dehors de surfaces: 308
WARNING: Nombre de centroïdes dupliqués:   881
Cleaning output topology
Reading features...
Accrochage des sommets passe 1 : sélection des points
Accrochage des sommets passe 2 : assignation des ancrages de sommets
Accrochage des sommets passe 3 : accrochage sur les points assignés
Sommets accrochés : 663
Nouveau sommet : 862
Intersections : 54331
Removed duplicates: 491
Modifications: 0
Removing dangles...
Removed lignes : 3
Removed dangles: 3
Removing bridges...
Removed lines: 0
Removed bridges: 0
Construction de la topologie pour la carte vectorielle 
<voronoi_areas at Test>...
Enregistrement des primitives ...
72112 primitives registered
139602 vertices registered
Construction des surfaces ...
31830 areas built
One isle built
Attachement des îles ...
Attachement des centroïdes ...
La topologie a bien été construite
Nombre de nœuds: 35661
Nombre de primitives: 72112
Nombre de points: 0
Nombre de lignes :0
Nombre de contours: 67490
Nombre de centroïdes: 4622
Nombre de surfaces: 31830
Nombre d'îles: 1
WARNING: Nombre de centroïdes dupliqués:   114
v.voronoi terminé.

This is the output of g.version -breg :
version=7.0.1
date=2015
revision=65800
build_date=2015-07-31
build_platform=i686-pc-mingw32
    ./configure  '--with-libs=/c/OSGeo4W/lib /c/OSGeo4W/apps/msys/lib 
/c/osgeo4w/usr/src/grass701/mswindows/osgeo4w/lib' 
'--with-includes=/c/OSGeo4W/include /c/OSGeo4W/apps/msys/include' 
--libexecdir=/c/OSGeo4W/bin --prefix=/c/OSGeo4W/apps/grass 
--bindir=/c/OSGeo4W/bin --includedir=/c/OSGeo4W/include --disable-x 
--without-x --with-cxx --enable-shared --enable-largefile 
--with-opengl=windows --with-fftw --with-freetype 
--with-proj-share=/c/OSGeo4W/share/proj 
--with-gdal=/c/osgeo4w/usr/src/grass701/mswindows/osgeo4w/gdal-config 
--with-geos=/c/osgeo4w/usr/src/grass701/mswindows/osgeo4w/geos-config 
--with-liblas=/c/osgeo4w/usr/src/grass701/mswindows/osgeo4w/liblas-config --with-sqlite 
--with-curses --with-regex --with-nls 
--with-freetype-includes=/c/OSGeo4W/include/freetype2 --with-odbc 
--with-cairo --with-cairo-includes=/c/OSGeo4W/include/cairo --with-postgres
libgis_revision=64733
libgis_date="2015-02-25 01:56:29 +0100 (st, 25 2 2015) "
proj4=4.8.0
gdal=1.11.2
geos=3.4.2
sqlite=3.7.17

I also tried on a Unix machine on which I built GRASS with the same results.

I tried to get a small subset of points and got down to 8 points 
producing a wrong output. Point subset and output image is also linked 
to this email.
I searched existing bugs and tried to increase resolution with g.region 
with no improvement;

Do you have any ideas ? Should I file in a bug or am I using the tools 
in the wrong way ?

Thanks for your thoughts,
Cev.


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