[GRASS-user] V.voronoi

[Benjamin Ducke]

The input map information suggests that you have linked more
than one attribute table (i.e. a multi-layered input map).
Make sure that when you run v.voronoi on the input map,
you specify the correct layer, that actually contains
all your input points.

Benjamin


Sampson, David wrote:
> Hey folks,
> 
> Looking for a some ideas and help.
> 
> I am ttrying to use the v.voronoi (in wingrass) tool and it is
> perplexing me with the results I am getting. Here is the scenario.
> 
> I am trying to anaylise the spatial distribution of road intersections.
> I started with a road network file from Statistics Canada, and clipped
> out the roads of the city of Ottawa for my subset. I created a new
> vector containing only the nodes of the Ottawa network. The resulting
> vector has the following basic stats
> 
> =========
> Type of Map:  vector (level: 2)                                          |
>  |                                                                           
> |
>  |   Number of points:       48156           Number of areas:     
> 0          |
>  |   Number of lines:        0               Number of islands:   
> 0          |
>  |   Number of boundaries:   0               Number of faces:     
> 0          |
>  |   Number of centroids:    0               Number of kernels:   
> 0          |
>  |                                                                           
> |
>  |   Map is 3D:             
> 0                                                |
>  |   Number of dblinks:      2
> ===========
> 
> The nodes represent both road terminations and intersections.
> 
> I am new to using Voronoi charts but when I run the v.voronoi script I
> expect it to create a polygon for each node.
> 
> Instead when I run the basic stats on the new Veronoi vector I get:
> 
> =============
>  Type of Map:  vector (level: 2)                                          |
>  |                                                                           
> |
>  |   Number of points:       0               Number of areas:     
> 1          |
>  |   Number of lines:        0               Number of islands:   
> 1          |
>  |   Number of boundaries:   4               Number of faces:     
> 0          |
>  |   Number of centroids:    0               Number of kernels:   
> 0          |
>  |                                                                           
> |
>  |   Map is 3D:             
> 0                                                |
>  |   Number of dblinks:      1       
> =============
> 
> I get a rectangular shape that is located just north of ONE of the nodes
> in the coverage. As I zoom out some other nodes apear surounding
> rectangualr shape…  The manual doesn't shed light on my situation.
> 
> Any help, experieince or knowledge would be great.
> 
> Cheers
> 
> 
> ------------------------------------------------------------------------
> 
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-- 
Benjamin Ducke, M.A.
Archäoinformatik
(Archaeoinformation Science)
Institut für Ur- und Frühgeschichte
(Inst. of Prehistoric and Historic Archaeology)
Christian-Albrechts-Universität zu Kiel
Johanna-Mestorf-Straße 2-6
D 24098 Kiel
Germany

Tel.: ++49 (0)431 880-3378 / -3379
Fax : ++49 (0)431 880-7300
www.uni-kiel.de/ufg