[mapserver-users] Classify raster image

[Andrea Goethals]

This works for version 3.3.011:

LAYER
  NAME forden
  TYPE raster
  DESCRIPTION "Forest Density"
  STATUS default
  MAXSCALE 4300000
  DATA grids/forden.tif
  CLASSITEM 'dummy'
  CLASS
     NAME "91-100 percent forest cover"
     EXPRESSION ([value] > 90 AND [value] < 101)
     COLOR 50 70 43
  END
  CLASS
     NAME "81-90 percent forest cover"
     EXPRESSION ([value] > 80 AND [value] < 91)
     COLOR 63 88 54
  END
  CLASS
     NAME "71-80 percent forest cover"
     EXPRESSION ([value] > 70 AND [value] < 81)
     COLOR 76 106 65
  END
  CLASS
     NAME "61-70 percent forest cover"
     EXPRESSION ([value] > 60 AND [value] < 71)
     COLOR 89 124 76
  END
  CLASS
     NAME "51-60 percent forest cover"
     EXPRESSION ([value] > 50 AND [value] < 61)
     COLOR 102 142 87
  END
  CLASS
     NAME "41-50 percent forest cover"
     EXPRESSION ([value] > 40 AND [value] < 51)
     COLOR 115 160 98
  END
  CLASS
     NAME "31-40 percent forest cover"
     EXPRESSION ([value] > 30 AND [value] < 41)
     COLOR 128 178 109
  END
  CLASS
     NAME "21-30 percent forest cover"
     EXPRESSION ([value] > 20 AND [value] < 31)
     COLOR 141 196 120
  END
  CLASS 
     NAME "1-10 percent forest cover"
     EXPRESSION ([value] > 0 AND [value] < 11)
     COLOR 182 255 156
  END
END

Andrea

> 
> Berend Veldkamp wrote:
> >
> > Hi,
> > How do I classify a raster image, like:
> >  0-10 -> red
> > 10-20 -> orange
> > 20-30 -> yellow
> >
> > I know I can reclassify the tiff images, but can this also be done
> > on-the-fly.
> 
> I think you can use the special attribute name "VALUE" to represent the
> pixel values in your class expressions... so the following should
> hopefully work:
> 
>   CLASSITEM "VALUE"
>   CLASS
>     EXPRESSION ([VALUE] < 10)
>     COLOR 255 0 0
>   END
>   CLASS
>     EXPRESSION ([VALUE] < 20)
>     COLOR ...
>   END
>   CLASS
>     EXPRESSION ([VALUE] < 30)
>     COLOR ...
>   END
> 
> --
> ------------------------------------------------------------
>  Daniel Morissette               morissette at dmsolutions.ca
>  DM Solutions Group              http://www.dmsolutions.ca/
> ------------------------------------------------------------
>   Don't put for tomorrow what you can do today, because if
>       you enjoy it today you can do it again tomorrow.