[GRASS-user] Again about direction

[Micha Silver]

Sofina Natalia wrote:

> Hello everybody !
> I would like to compare values for raster and vector points at 
> positions of vector points. Raster is filtered with edge detection 
> function. And as compared value should be "direction".
>
> How can I get now the information about direction in each point for 
> vector map? Vector points should have one's own values of the 
> direction. Then I'll compare this values from raster and vector.
>
If I understand correctly, you have a vector point layer with an 
attribute column "direction". And you have a raster which also shows 
directions. What you want is to add to the vector points an additional 
column "Raster_direction" which shows directions from the raster. Is 
this correct?


If so then you have two simple steps. First add the additional column to 
the vector:

v.db.addcol <vector_layer> col="rast_dir integer"

Then get the raster values into the vector with:

v.what.rast vect=<vector_layer> rast=<raster_layer> col=rast_dir


> Many thanks.
>
>
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-- 
Micha Silver
Arava Development Co. +972-52-3665918
http://surfaces.co.il