[mapserver-users] minscaledenom puzzle, Mapserver 6.0.1

[Peter N. Schweitzer]

Surely I have misunderstood minscaledenom or otherwise have misused it.

I just switched over to Mapserver 6.0.1 (Linux, CentOS, data in
PostgreSQL+PostGIS)

The web page is http://mrdata.usgs.gov/mineral-resources/mrds-us.html
Feature type is point.  The classes from the map file are these:

   labelitem "site_name"
   labelmaxscaledenom 250000
   classitem "dev_stat"
   class
     maxscaledenom 7000000
     expression ('[dev_stat]' == 'Producer' or '[dev_stat]' == 'Past Producer')
     name "Mine, past or present producer"
     color 160 0 0
     symbol "mine"
     size 5
     label
       color 0 0 0
       size 10
       type truetype
       font arial
       position cr
       offset 4 4
       end
     end
   class
     maxscaledenom 7000000
     expression ('[dev_stat]' == 'Prospect' or '[dev_stat]' == 'Occurrence')
     name "Prospect or occurrence"
     color 0 160 0
     symbol "opensquare"
     size 5
     end
   class
     maxscaledenom 7000000
     expression ('[dev_stat]' == 'Plant')
     name "Processing plant"
     color 0 0 160
     symbol "mine"
     size 6
     label
       color 0 0 0
       size 10
       type truetype
       font arial
       position cr
       offset 4 4
       end
     end
   class
     maxscaledenom 7000000
     expression ('[dev_stat]' == 'Unknown')
     name "Unknown"
     color 0 0 0
     symbol "occurrence"
     size 6
     end
   class
     minscaledenom 7000000
     color 160 0 0
     symbol 0
     end

Under mapserver 5.6.7, this generated red pixels for every point when
the map is zoomed out; those are replaced by the square symbols when
the map is zoomed in.

But under 6.0.1, I am not getting the 1-pixel symbols when zoomed out.
I assumed that the last class defined above would apply when the scale
is coarser than 1:7M.

Here is the OpenLayers command that loads this layer:

   var wms = new OpenLayers.Layer.WMS(
     "Mineral Resources",
     "http://mrdata.usgs.gov/cgi-bin/mapserv?",
     {
       map: 'mrds.map',
       transparent: 'true',
       layers: 'mrds'
       },
     {
       singleTile: 'true',
       ratio: 1
       }
     );

Would some modification of my map file or my OpenLayers javascript
bring back my little red pixels?

Thanks for any help you might offer.

Peter
-- 
Peter N. Schweitzer (MS 954, U.S. Geological Survey, Reston, VA 20192)
(703) 648-6533  FAX: (703) 648-6252  email: pschweitzer at usgs.gov
<http://geology.usgs.gov/peter/>