[GRASSLIST:5211] v.what.rast question

GRASS GRASS user
1

I am trying to transfer a stream characteristic (gradient) from a line
vector coverage to a set of riparian polygons (an area vector
coverage). I figured the easiest way to to this (since I am only
interested in one column) was to convert the line coverage to a raster
coverage with using the gradient column as the attribute, then to use
v.what.rast to insert the corresponding values into the riparian
polygons' attribute table. However, when I use v.what rast, I get no
values uploaded to the table. Here were my commands:

v.to.rast in=streams out=stream_grad col=gradient
v.what.rast vect=riparian rast=stream_grad col="GRADIENT"

Am I going about this incorrectly? If not, why doesnt this work?

Thanks,
Chris

2

Any idea, then, what the appropriate function for moving attributes
from one vector attribute to another is? v.overlay does not seem to
work for this either.

Thanks in advance,
Chris

On Wed, 22 Dec 2004 08:57:12 +0100 (CET), blazek@itc.it <blazek@itc.it> wrote:

> I am trying to transfer a stream characteristic (gradient) from a line
> vector coverage to a set of riparian polygons (an area vector
> coverage). I figured the easiest way to to this (since I am only
> interested in one column) was to convert the line coverage to a raster
> coverage with using the gradient column as the attribute, then to use
> v.what.rast to insert the corresponding values into the riparian
> polygons' attribute table. However, when I use v.what rast, I get no
> values uploaded to the table. Here were my commands:
>
> v.to.rast in=streams out=stream_grad col=gradient
> v.what.rast vect=riparian rast=stream_grad col="GRADIENT"
>
> Am I going about this incorrectly? If not, why doesnt this work?
>
> Thanks,
> Chris

v.what.rast works only with points.

Radim