David Sampson wrote:
> 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.
I think that unlike most vector modules v.voronoi works in the current region.
Try 'g.region -p vect=nodes_map' before running v.voronoi to set the zoom to
cover all points in the input map.
?
Hamish
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