Hi , I have a large vector shapefile I would like to split into many smaller tiles of equal size. Can somebody suggest a way to do this in GRASS 6.4 (either Windows or Linux).
Also is it possible to use scripts (for batch processing) under the Windows version of GRASS?
Many thanks
George
--
View this message in context: http://n2.nabble.com/Splitting-shapefile-tp2536771p2536771.html
Sent from the Grass - Users mailing list archive at Nabble.com.
On Thu, Mar 26, 2009 at 6:50 AM, georgew <gws293@hotmail.com> wrote:
Hi , I have a large vector shapefile I would like to split into many smaller tiles of equal size. Can
somebody suggest a way to do this in GRASS 6.4 (either Windows or Linux).
You could use v.mkgrid to generate a grid. Then loop over all categories
in this grid (v.categories) and use v.overlay to intersect.
Also is it possible to use scripts (for batch processing) under the Windows version of GRASS?
Yes, I think so.
Markus
You could use v.mkgrid to generate a grid. Then loop over all categories
in this grid (v.categories) and use v.overlay to intersect.
Thank you Markus, I had no problem in creating the grid with:
v.mkgrid --overwrite map=grid_vect grid=20,20 box=10000,10000
(only struck a small bug in the GUI which does not let you enter two values for the grid (eg 20,20) so I had to enter the command in the command box).
But had no success at all using v.category and v.overlay to create individual map tiles for each of the 400 tiles in the grid. I suspect I am not using v.category properly but could not find an example that could help me.
My understanding is that for v.overlay to work, the b-input must be a single tile, then the AND intersection will extract the a-input features for the area under that tile. But I could not find a way to extract a single tile out of the grid.
What am I missing?
Do I need to reduce the current region to the single tile before v.overlay and then loop through all the tiles that way?
George
--
View this message in context: http://n2.nabble.com/Splitting-shapefile-tp2536771p2551084.html
Sent from the Grass - Users mailing list archive at Nabble.com.