Hi all,
I'm working on a road network vector file, however I have encountered
a small issue, and I would be very grateful if you could please offer
suggestions,
I'm unsure why this issue is arising, as I have worked with this data
a few months ago with no problems.... any advice is greatly appreciated.
Thanks
I'm working with road collision data.... and I have a slight issue
with excluding collisions that have been snapped >500m to a particular
route.
The problem arises when:
I use v.extract.where in the GRASS toolbox setting Distance<500 and
then I load the new map, a large proportion of the collisions are not
included in this new map (I have also changed setting to have Distance
<1000, however the same map is produced as the Distance <500m map)
I have outlined my steps below:
(I'm working on MAC OSX 10.5.8, QGIS version 1.4.0 Enceladus)
1) Loaded road into GRASS (using v.in.ogr.qgis)
2) Loaded collisions into GRASS (using v.in.ogr.qgis)
3) Created 3 new columns (X,Y,Distance) in the collisions attribute
table (using v.db.addcol)
4) used v.distance to calculate 'minimum distance to next
feature' (also recorded the x,y co-ordinates in the corresponding x,y
columns)
5) used v.extract.where setting Distance < 500 called the output
'collisions500' and then I reloaded the collisions500
I have tried shutting down QGIS / restarting/ reloading ..... but the
same problem still occurs....
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