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

[maven apache]

Thanks I have tried it ,and I found each transfered vector map is
not compatible with the real color position of the image......

2009/6/18 Moritz Lennert <mlennert at club.worldonline.be>

> 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
>
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