don't know if I unterstood you right, but what about buffering your
polygons (v.buffer with buffer=50m), i.e. the buildings. So you get a
map of overlapping areas where features not more far away than 50
meters. Afterwards you can use v.to.rast for rasterizing the buffer
zones and describing small towns for you case.
Regards,
Christian.
Am Sonntag, den 15.06.2008, 08:43 -0700 schrieb Gabriele N.:
Hi all
I have 2 vector polygonal; one representing the buildings and another that
represents the infrastructure.
I think to put them together with v.patch.
I have to create another vector polygonal, which is to enclose all the
polygons that are close to each other within 50 metres. I need to identify
small towns.
How can I do?
1) v.patch
2) v.distance?
3)?
Thank you very much
Gabriele
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Indeed this was doing. I made the buffer (but on many polygons gives a bit
of problems)
and now , as suggested by you, I can go to raster with v.to.rast.
Or should I try to dissolve the buffer by working again with the vector.
Thanks
Gabriele
Christian Schwartze-2 wrote:
Hi,
don't know if I unterstood you right, but what about buffering your
polygons (v.buffer with buffer=50m), i.e. the buildings. So you get a
map of overlapping areas where features not more far away than 50
meters. Afterwards you can use v.to.rast for rasterizing the buffer
zones and describing small towns for you case.
Regards,
Christian.
Am Sonntag, den 15.06.2008, 08:43 -0700 schrieb Gabriele N.:
Hi all
I have 2 vector polygonal; one representing the buildings and another
that
represents the infrastructure.
I think to put them together with v.patch.
I have to create another vector polygonal, which is to enclose all the
polygons that are close to each other within 50 metres. I need to
identify
small towns.
Indeed this was doing. I made the buffer (but on many
polygons gives a bit of problems)
v.buffer can have some errors. It is currently being rewritten and we should have something better in place by the end of the summer.
Before then, and if you are converting to raster anyway, you might try the r.buffer module. it is much healthier.
and now , as suggested by you, I can go to raster with
v.to.rast. Or should I try to dissolve the buffer by working
again with the vector.
I don't remember if it was suggested before, but you could convert back to vector and run v.clean with the remove small areas tool so only big blobs remain.
another idea is to buffer around individual buildings with an output buffer value of 1, then use r.series to add all the buffer areas together so overlap areas are equal 2,3,4,.. then r.grow or use 'r.neighbors maximum' to somehow extract/flood fill areas containing overlap. ?