Raster Issues in MapServer 4.4.1

[Bruce Raup]

Frank,

As a co-worker of Chris's, I've been following this conversation closely.

It seems to me that proj is behaving reasonably already:  you give it
nonsensical input, it gives you nonsensical output.  That is, if you
give it lon/lat coordinates in Sweden and try to project them to UTM
zone 8 (Alaska, central meridian -135), you should expect weird
results.

I think the problem is that mapserver is giving proj nonsensical
input.  The mapfile contains this layer for one of the Alaska images:

  LAYER
    NAME "taku_L7"
    GROUP RASTERS
    TYPE RASTER
    STATUS OFF
    DATA p058r019_7t20010815_z08_421RGB.tif
    MAXSCALE 22331381.8
    PROJECTION
      "proj=utm"
      "ellps=WGS84"
      "zone=8"
      "north"
      "no_defs"
    END
  END

The projection is specified as Zone 8.  Yet, when you zoom into
Sweden, Mapserver thinks it needs to display the zone 8 image anyway.

Or maybe it does the reprojection before deciding whether to display
or not?  If that's what's going on, then it seems that you could fix
it either by doing what you suggested (having proj fail in such cases,
in which case mapserver could be made to ignore that layer), or have
mapserver pay attention to the location of the zones of the layers
relative to the map extents.

Bruce

--
Bruce Raup
http://cires.colorado.edu/~braup/


-- 
Bruce Raup
http://cires.colorado.edu/~braup/