Running 7.3.svn here on Slackware-14.1/-14.2 and looking at both vector
and raster modules I don't see how to overlay a vector map on a raster map
to divide the raster into two sections.
The raster map has the same value in every cell. I want to change the
value in cells north of a vector map of a road. If there's a workflow
description in the docs please point me to it. Otherwise, please suggest a
procedure to accomplish this.
TIA,
Rich
Rich Shepard wrote
Running 7.3.svn here on Slackware-14.1/-14.2 and looking at both vector
and raster modules I don't see how to overlay a vector map on a raster map
to divide the raster into two sections.The raster map has the same value in every cell. I want to change the
value in cells north of a vector map of a road. If there's a workflow
description in the docs please point me to it. Otherwise, please suggest a
procedure to accomplish this.TIA,
Rich
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What about?:
-g.region by your raster
-v.in.region to get a vector area of your raster
-split the vector area by your road
-Add a new attribute column and give 1 for the area which shouldn't change
and the other the number which you want to divide
-v.to.rast by attribute
-r.mapcalc with some if statement
-----
best regards
Helmut
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On Tue, 6 Jun 2017, Helmut Kudrnovsky wrote:
What about?:
-g.region by your raster
-v.in.region to get a vector area of your raster
-split the vector area by your road
-Add a new attribute column and give 1 for the area which shouldn't change
and the other the number which you want to divide
-v.to.rast by attribute
-r.mapcalc with some if statement
Helmut,
I thought there would be a need to transform maps from raster to vector
(or the other way) but I did not work out the appropriate sequence as you
have. This reflects my relative lack of experience doing complex processing
with grass.
Thank you very much,
Rich
On Tue, 6 Jun 2017, Helmut Kudrnovsky wrote:
What about?:
-g.region by your raster
-v.in.region to get a vector area of your raster
-split the vector area by your road
I have a line that defines the two areas. When I try to use v.overlay to
union the two maps (using ain=line, bin=area and op=or) the module tells me
I cannot add a line to an area.
The v.overlay manual page tells me that the union operator can be applied
only to an area, and that the ainput type can be line, area, or auto while
the binput type must be an area.
The v.split module works on lines.
Cluestick needed,
Rich