On Mon, Jun 23, 2008 at 9:08 PM, Markus Neteler <neteler@osgeo.org> wrote:
Rainer,
I suggest to try the snap parameters of v.in.ogr first. Maybe the SHAPE
file is full of gaps and slivers (commonly found, even in governmental
data).
*Small* snapping values might cure it. Be careful to not snap, say,
Africa to a triangle 
Markus
Thanks Markus,
but the information is there. If I display the layer and select
layer=2, I see the overlapping areas, and if I click i=on them to get
information (v.what -a map=fires@simulation ...), I get the following
info:
East: 255207.46888
North: 6235456.43154
Map: fireHistory
Mapset: simulation
Type: Centroid
Line: 3202
Layer: 1
Category: 4
Driver: dbf
Database: /home/rkrug/Documents/Projects/AlienSpread/R/../grass/simulation/dbf/
Table: fireHistory
Key column: cat
cat : 4
YEAR : 2005
Layer: 1
Category: 178
Driver: dbf
Database: /home/rkrug/Documents/Projects/AlienSpread/R/../grass/simulation/dbf/
Table: fireHistory
Key column: cat
cat : 178
YEAR : 1993
Layer: 1
Category: 208
Driver: dbf
Database: /home/rkrug/Documents/Projects/AlienSpread/R/../grass/simulation/dbf/
Table: fireHistory
Key column: cat
cat : 208
YEAR : 1995
Layer: 2
Category: 3 <<---
and the one value marked by <<-- is the one which IO want to extract
into a raster or vector map.
Even if I do
v.extract input=fireHistory@simulation output=fires
type=point,line,boundary,area layer=2
it gives me the areas, but no associated attribute table.
On Mon, Jun 23, 2008 at 12:13 PM, Rainer M Krug <r.m.krug@gmail.com> wrote:
Hi
I am importing a vector layer from a shape file as follow, and get the
warning below:
> v.in.ogr dsn=/home/rkrug/Documents/Projects/AlienSpread/data/input/
> layer=fireHistory output=fireHistory --overwrite
WARNING: 703 areas represent more (overlapping) features, because polygons
overlap in input layer(s). Such areas are linked to more than 1
row in attribute table. The number of features for those areas is
stored as category in layer 2
I am aware of that, and I want to create a raster layer with the
number of features overlapping in each location. As I ultimately need
a raster layer, I thought to use the following, but I get the error
message below:
> v.to.rast input=fireHistory layer=2 output=mf use=attr column=category
> --overwrite
ERROR: Unable to get layer info for vector map
Why is that?
Is there another way of getting the number of overlapping features per
cell?
Thanks
Rainer
--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)
Plant Conservation Unit
Department of Botany
University of Cape Town
Rondebosch 7701
South Africa
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--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)
Plant Conservation Unit
Department of Botany
University of Cape Town
Rondebosch 7701
South Africa