On 03/02/14 11:48, Johannes Radinger wrote:
Hi Moritz,
hi all,
sorry for my late response. I can now provide an example using the NC
dataset.
First I needed to generate data (rasterized line/river) similar to the
data input I am using.
So I transformed the streams vector into a raster using the attribute
column FCODE as
value for the raster (v.to.rast input=streams@PERMANENT output=r_streams
column=FCODE)
Thereafter I thinned the raster (r.thin input=r_streams@PERMANENT
output=r_streams_thin). The
output corresponds to a map similar to my original map I am using.
Now I wanted to (back-)transform the raster map back to lines where the
resulting line segments should
correspond to the segments visible in the raster map
(r.to.vect input=r_streams_thin@PERMANENT output=v_r_streams_thin
feature=line). However, lines
are broken only where different lines join.
I attached a screenshot that illustrates my task. You can see the raster
map with three
different segments (two different values) for that single tribuatry
(indicated by blue-yellow-blow).
However when the raster gets transformed into a line this information
gets lost, as lines
are not broken where a new raster value starts. Any suggestions how to
solve such
a task?
Same response as last time: try the -v flag of r.to.vect.
Moritz
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