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.
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.
--
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
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
____________________________________________________________________________________
Get easy, one-click access to your favorites.
Make Yahoo! your homepage. http://www.yahoo.com/r/hs
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.
v.voronoi has no layer= option.
Note that the help page says:
BUGS
Only attribute table of field 1 is copied.
Hamish
____________________________________________________________________________________
Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs
In that case, I suppose you still need to make
sure that the input points are actually in layer 1?
Benjamin
Hamish wrote:
David Sampson wrote:
| Number of dblinks: 2
Benjamin Ducke wrote:
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.
v.voronoi has no layer= option.
Note that the help page says:
BUGS
Only attribute table of field 1 is copied.
Hamish
____________________________________________________________________________________
Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs
--
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
May I make a suggestion have a small comment added to the documentation
page at http://grass.itc.it/grass63/manuals/html63_user/v.voronoi.html
to include a note concerning setting the region. In the example it shows
a step to set the region, which makes sense now, but upon first reading
it I did not catch on.
Cheers
-----Original Message-----
From: Hamish [mailto:hamish_nospam@yahoo.com]
Sent: Wednesday, November 14, 2007 17:40
To: Sampson, David
Cc: grassuser@grass.itc.it
Subject: Re: [GRASS-user] V.voronoi
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
________________________________________________________________________
____________
Get easy, one-click access to your favorites.
Make Yahoo! your homepage. http://www.yahoo.com/r/hs