[GRASS-user] can the grass calculate the area of different color for a image(tiff or other?)

[Moritz Lennert]

On 18/06/09 14:59, maven apache wrote:
> 
> 
> 2009/6/18 Moritz Lennert <mlennert at club.worldonline.be 
> <mailto:mlennert at club.worldonline.be>>
> 
>     On 18/06/09 14:31, maven apache wrote:
>      >         Also I found that I can see only five color from the tiff
>      >         swi.tiff, and yesterday I get five category with the same
>      >         steps(import and composite then calculate ), they are
>      >         "0
>      >         9321 26425 31744 32736   ";, but today it change to six!!
>      >
>      > Maybe I  remembered it wrongly. (*^__^*)
>      >
>      >
>      >         And acturlly I want to extract each color and export them
>     to a
>      >         vector map, I am looking the proper commond.
>      >
>      > It seems that there is no corresponding command to  achieve this
>     goal£¿
> 
> 
>     Please start by reading:
> 
>     http://grass.osgeo.org/grass64/manuals/html64_user/rasterintro.html
>     http://grass.osgeo.org/grass64/manuals/html64_user/vectorintro.html
> 
>     The command you are looking for is r.to.vect (I see it is not mentioned
>     in the rasterintro. Should be...).
> 
> It seems that the r.to.vect is to transfer the hole raster map to a 
> vector,but I want to transfer each category to a vector.... 

The easiest solution is probably a combination of r.to.vect + v.extract.

Moritz