Overview Images in Mapserver

[Kenneth Denson]

I have 9 24-bit geotiffs that I've indexed using gdaltindex. They display
just perfectly in mapserver, but the problem is that it can be a little
slow. I've used gdaladdo to add some overview levels to the geotiffs, but
how do I tell mapserver to use those overviews? Or is it doing it
automatically? Just for reference, the following is the information about
the geotiffs and how their layer looks in mapserver.

Size is 10000, 10000
Coordinate System is `'
Origin = (2360000.000000,850000.000000)
Pixel Size = (0.500000,-0.500000)
Metadata:
  TIFFTAG_SOFTWARE=Adobe Photoshop 7.0
  TIFFTAG_DATETIME=2003:11:17 17:34:02
Corner Coordinates:
Upper Left  ( 2360000.000,  850000.000)
Lower Left  ( 2360000.000,  845000.000)
Upper Right ( 2365000.000,  850000.000)
Lower Right ( 2365000.000,  845000.000)
Center      ( 2362500.000,  847500.000)
Band 1 Block=10000x1 Type=Byte, ColorInterp=Red
  Overviews: 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 5000x5000, 2500x2500,
1667x1667, 1250x1250, 1000x1000
Band 2 Block=10000x1 Type=Byte, ColorInterp=Green
  Overviews: 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 5000x5000, 2500x2500,
1667x1667, 1250x1250, 1000x1000
Band 3 Block=10000x1 Type=Byte, ColorInterp=Blue
  Overviews: 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 3x3, 5000x5000, 2500x2500,
1667x1667, 1250x1250, 1000x1000


LAYER
    NAME "orthophoto"
    METADATA
      "tiles" "orthophoto"
    END
    STATUS ON
    TILEINDEX "tiles.shp"
    TILEITEM "location"
    TYPE RASTER
END

Kenneth Denson
Spatial Focus Inc.
kdenson at spatialfocus.com