On 24/03/14 18:24, Annalisa Minelli wrote:
Hello Moritz,
I tried your solution and since I generated the path using the same
v.net.path with the same -s flag (which preserves the segments) that you
suggest, when I do the v.distance trying to "copy" the attribute cat
from the net segments it seems not to work properly - I mean, it copies
"something" but that "something" is wrong in the sense that it takes the
category of the element NEAR the studied one, not 'under' even
specifying a dmax=0..
v.net.path input='gridCat' output='tmpPath2' file='tmpCoord2' -s
v.db.droptable map='tmpPath2' -f
v.category input='tmpPath2' output='tmpPath4a' option='del'
v.category input='tmpPath4a' output='tmpPath2' option='add')
v.db.addtable map='tmpPath2' columns='cat integer,tmpcat integer'
v.distance from='tmpPath2' from_type='line' to='gridCat' to_type='line'
upload='cat' column='tmpcat' dmax=0
here a pic of my situation: http://oi62.tinypic.com/2epopcj.jpg
in red the tmpPath2 and tmpcat value as label
in black the gridCat and the value of the category as label
The man page says "For lines to lines, say line A to line B, v.distance
calculates the shortest distance of each vertex in A with each segment
(not vertex) in B. The module then calculates the shortest distance of
each vertex in B to each segment in A. The overall shortest distance of
A points to B segments and B points to A segments is used. Additionally,
v.distance checks for intersections. In case of intersections, the first
intersection found is used and the distance set to zero."
I guess that identity is not the same as intersection...
Markus ?
Moritz
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