[GRASSLIST:2872] Re: problem with v.buffer

Dear all,
I follow your help and it wors very well but if the buffer overlap?
I see that if I convert to rast a vector with two circles overlapped the
circles take the same value (the value of one of these).
I'd like to have the a rast with the areas not overlapped with the rigth value
of the vector circles and the area overlapped with a value = at the sum of
the value of the two circles.
Is posiible that or something near at that?

Thank you very much.

Leonardo

Ciao,

scusa, ok, now I got your problem. Yes, v.buffer does NOT transfer the
attributes because of potential buffer overlap (which cannot be resolved
automatically).

Solution, if circles do not overlap:

#Example for Spearfish data (use v.in.sites to convert old sites data):

v.buffer input=archsites output=circles type=point buffer=200

# change original points to centroids:
v.type in=archsites out=archcentroids type=point,centroid

# patch circles and centroids:
v.patch in=archcentroids,circles out=circles_db

# attach attributes, either use
# db.copy ...
# or link to the original table:
v.db.connect map=circles_db table=archsites field=1 key=cat driver=dbf
database='$GISDBASE/$LOCATION_NAME/$MAPSET/dbf'

d.vect circles_db
d.what.vect circles_db

I have added this example to the documentation.

Cheers

Markus

On Fri, Feb 20, 2004 at 03:46:20PM +0100, Leonardo Lami wrote:
> Dear Markus,
> I am Leonardo Lami, a collaborator of Paolo Cavallini (Faunalia), and I'm
> working on a a environmental model with him.
> I'm working with the command v.buffer but I have a problem:
> I'd like to create circle buffer vectors (type area) of some points where
> the category of the single circle centroid results to have the value of
> the category of the relative point.
>
> It's possibile to do that in automatic?
> If not, would it be hard for you make this optional for the command
> v.buffer?
>
> Thank you a lot
>
> Leonardo

On Monday 08 March 2004 13:45, Leonardo Lami wrote:

Dear all,
I follow your help and it wors very well but if the buffer overlap?
I see that if I convert to rast a vector with two circles overlapped the
circles take the same value (the value of one of these).

Output areas have only one category (1).

I'd like to have the a rast with the areas not overlapped with the rigth
value of the vector circles and the area overlapped with a value = at the
sum of the value of the two circles.
Is posiible that or something near at that?

I agree that categories of input vectors are sometimes useful, unfortunately
this is not possible in v.buffer. For now, you have to do it yourself.
Using 'v.distance -a from_type=centroids max=<buffer_size> upload=cat'
you get categories of all features within your buffer size buffer_size.

Radim