[GRASSLIST:5539] Re: v.mkgrid extract grid sections

[Dylan Beaudette]

On Wednesday 26 January 2005 06:09 pm, Hamish wrote:
> > I have used v.mkgrid (GRASS6-CVS) in the past to make vector grids,
> > and all  has been well.
>
> ..
>
> > However, this morning I tried to extract a single square from the
> > output from  v.mkgrid, and was only able to get either a single
> > centroid (almost correct),  or the entire boundary (not good). Since
> > the boundaries do not have CATs,  there is no way for me to extract a
> > single boundary...
>
> ..
>
> > Any ideas?
>
> what about
>
>   v.category type=boundary option=add
>
> to add category numbers to the boundaries?
>

Thanks! ... this gives the boundaries CATs... but for some reason, each grid 
square is made up of about 8 line segments (3 for top and bottom lines, 1 for 
each vertical line)... 

My hope is that i can make each grid "cell" into a discreet polygon, that can 
be used to set the region -- i.e. so that i can accurately subsample a larger 
map.

thanks!

-- 
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341