[GRASS-user] keeping simple areas after v.buffer

GRASS GRASS user
1

Hi List,

I have a vector layer of points.
After I expand the points to areas with:

v.buffer -t input=in output=out distance=500

some of the out areas overlap. I'd like to plot one area like this:

d.vect out where="cat == 2" fill_color=none

but when I do, I see all of the overlapping circles within the 500 m circle surrounding point 2. That is, I see the "o" that I want, but within it I see some "(" and ")" shapes where other areas overlap parts of the "o".

I can't seem to to use v.clean on the entire vector. Before plotting one area I can extract it with v.extract and then v.clean with tool=rmarea, but this seems like an overly complicated approach, and the original DB still has the issue. Is there another tool to clean this up, or another way to generate the buffers around the points, to avoid this issue?

Thanks,

  -k.

2

On 07/03/17 13:39, Ken Mankoff wrote:

Hi List,

I have a vector layer of points. After I expand the points to areas
with:

v.buffer -t input=in output=out distance=500

some of the out areas overlap. I'd like to plot one area like this:

d.vect out where="cat == 2" fill_color=none

If border lines are not important, you could do the contrary:

d.vect out where="cat == 2" color=none

I can't seem to to use v.clean on the entire vector. Before plotting
one area I can extract it with v.extract and then v.clean with
tool=rmarea,

Just running v.extract -d is enough, no need for v.clean.

but this seems like an overly complicated approach, and
the original DB still has the issue.

We do not consider this an issue, but a feature :wink:

Is there another tool to clean
this up, or another way to generate the buffers around the points, to
avoid this issue?

No, AFAIK, the only two solutions you have are to either

1) loop over the points and call v.buffer on each one on its own
2) after creating all buffers at once, loop over the cat values and extract each buffer into a separate map using v.extract -d.

The big question is: besides the question of aesthetics in visualisation, do you have another reason why you wish to have each buffer (including overlapping ones) separate ?

Moritz

3

On Tue, Mar 7, 2017 at 7:50 AM, Moritz Lennert <mlennert@club.worldonline.be

wrote:

Just running v.extract -d is enough, no need for v.clean.

I had not noticed the "-d" flag. This solves the issue.

Thank you!

   -k.