[GRASS-user] random points through multiple vector maps

GRASS GRASS user
1

Friends,

    I am trying to drop random points through two vector maps to establish the correspondence between them. I couldn't figure out how to do that with v.random so I created a database table with 10,000 random points within the bounds of the region, and then used v.in.db to bring the points in as a vector map. Then I tried v.what.vect using the random points on a vegetation map, but v.what.vect failed as noted below

v.what.vect map=rnd_points column=vmap_veg qmap=vmap qcolumn=vegtype
Finding nearest features...
  100%
Update vector attributes...
  100%
5049 categories - no nearest feature found
v.distance complete. 10000 records updated.

So 10,000 points were updated to NULL because no nearest feature was found. Can somebody explain to me what went wrong or how to fix it?

OS: 3.12.6-1-ARCH
GRASS: grass70-svn

Thanks, Dave
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
David W. Roberts office 406-994-4548
Professor and Head FAX 406-994-3190
Department of Ecology email droberts@montana.edu
Montana State University
Bozeman, MT 59717-3460

2

Friends,

    Sorry, this DID work for points inside the polygon of interest.

    I guess I was too tired.

Dave

On 05/30/2014 05:42 PM, Dave Roberts wrote:

Friends,

    I am trying to drop random points through two vector maps to
establish the correspondence between them. I couldn't figure out how to
do that with v.random so I created a database table with 10,000 random
points within the bounds of the region, and then used v.in.db to bring
the points in as a vector map. Then I tried v.what.vect using the
random points on a vegetation map, but v.what.vect failed as noted below

v.what.vect map=rnd_points column=vmap_veg qmap=vmap qcolumn=vegtype
Finding nearest features...
  100%
Update vector attributes...
  100%
5049 categories - no nearest feature found
v.distance complete. 10000 records updated.

So 10,000 points were updated to NULL because no nearest feature was
found. Can somebody explain to me what went wrong or how to fix it?

OS: 3.12.6-1-ARCH
GRASS: grass70-svn

Thanks, Dave

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
David W. Roberts office 406-994-4548
Professor and Head FAX 406-994-3190
Department of Ecology email droberts@montana.edu
Montana State University
Bozeman, MT 59717-3460