mapserver rasters scale

[David Fawcett]

I don't believe that this answers your central question, but you may want to take a look at your PROJECTION block.  

        PROJECTION
          "init=esri:27582"
        END

should probably read

        PROJECTION
          "init=epsg:27582"
        END

This may not be causing any problems right now, but if you add projection blocks to your layers, I am guessing that you will see an error.

For your primary question, I am guessing that Ed will jump right in.  My guess is that MapServer assumes a screen dpi that is not 250.  I believe that it is 72, but I am not sure.  You will probably have to convert your scale values to work with the default MapServer dpi.  

Play with the MINSCALE and MAXSCALE values in your Map file to see where the images swap.  

David.  


David J. Fawcett
MN Office of Environmental Assistance

>>> Stéphane RIFF <stephane.riff at CERENE.FR> 9/6/2004 3:57:34 AM >>>
Hi all,

I want to display some rasters layers :
       first one is 1/250000, 250 dpi
       second one is 1/25000, 250 dpi

Here is an extract of my map file :
    MAP
       UNITS METERS

       IMAGETYPE PNG

        PROJECTION
          "init=esri:27582"
        END

    LAYER
      NAME "250000"
      TILEINDEX "../data/250000"
      TILEITEM "LOCATION"
      TYPE RASTER
      STATUS ON
      OFFSITE 0 0 0
      MINSCALE 25000
      MAXSCALE 250000
      GROUP "carto"
      CLASS
        NAME "Fond raster 250000"
      END
    END

    LAYER
      NAME "25000"
      TILEINDEX "../data/25000"
      TILEITEM "LOCATION"
      TYPE RASTER
      STATUS ON
      OFFSITE 0 0 0
      MAXSCALE 25000
      GROUP "carto"
      CLASS
        NAME "Fond raster 25000"
      END
    END

This two layer switch well looking for mapserver scale.
The question i want to ask is why when i open a 1/250000 raster with
GIMP and set the scale to 100%,
it doesn't seem to correspond with what i see in mapserver at scale 250000.

In other words, if mapserver scale is 250000, does it means that the
view is at 1/250000 sacle???

I hope my question is understandable
Thanks