Symbols: cut-off and decluttering

[Dave Weaver]

I'm trying to plot symbols on a map (US highway shields), but am
experiencing problems.

If I ask MapServer for two adjacent squares of map, on the northern square I
get the top half a symbol (it is at the southern boundary) and on the
southern square there is no sign of that symbol. When the squares are later
put together to form a larger map, the effect is of half a symbol. Is there
a way to prevent partial symbols? The PARTIALS directive only appears to
apply to labels, not symbols.

I also note that if I render an overlapping square containing half of the
northern and half of the southern square, the symbol that is cut off in the
northern square is nowhere to be seen. What happened? Is there some sort of
decluttering going on? If so, how can this be controlled?

Northern tile: http://www.screenshots.cc/view_image/9fb511255/1.png
Southern tile: http://www.screenshots.cc/view_image/ee8631252/3.png
Overlap tile (halfway between northern & southern):
http://www.screenshots.cc/view_image/c0f0a1216/2.png


Below is some relevant stuff from the map file:

SYMBOL
  NAME "Interstate"
  TYPE PIXMAP
  IMAGE "/home/map/shapes/PB13/shields/INTERSTATE_ALPHA.PNG"
END

LAYER
    NAME         us_interstate_symbols_level_8
    DATA         "/home/map/shapes/PB13/Interstate_symbols_level_8"

    STATUS       OFF
    TYPE         ANNOTATION
    LABELCACHE on
    LABELITEM "Route"
    MAXSCALE       2407465
    MINSCALE       1203732
    LABELMAXSCALE          2407465
    LABELMINSCALE          1203732
    TRANSPARENCY 90
    PROJECTION
      "init=epsg:4326"
    END
    METADATA
        wms_title       us_interstate_symbols
        "wms_onlineresource"
"http://wxtile2.wsi.com:85/cgi-bin/mapserv?map=map/labeltest.map&
"
        "wms_srs"       "EPSG:4326 EPSG:900913"
    END
    CLASS
        STYLE
                SYMBOL "Interstate"
        END
      LABEL
                TYPE truetype
                FONT "tahoma"
                SIZE 7
                #ANGLE auto
                POSITION cc
                COLOR 255 255 255
                BACKGROUNDCOLOR 0 84 146
                PARTIALS FALSE
                FORCE TRUE
         END
    END
END

Thanks,
Dave.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/mapserver-users/attachments/20071220/d23dc3e2/attachment.htm>