WMS tiles & artifacts

[Tim Schaub]

>> I have been trying to marry MapServer with Google Map with 90% success
>> to overlay lots of "markers", but when a point generated from a layer in
the
>> mapfile touches the edge of a tile, there's an artifact in the shape of a
>> horizontal black line.
>
>Looks like a manifestation of bug #1861 
>(http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=1861)
>

This looks like a duplicate of bug #1719 to me
(http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=1719)

I included all the data necessary to reproduce the problem there.  It is
closed and marked as wontfix - because it's a problem with GD instead of
MapServer.

If you want to use a tiled map interface and get around these tile edge
artifacts, you can choose from two existing solutions.

Ka-Map gets around this problem by trimming off the edge of metatiles
(http://ka-map.maptools.org/).

Or you can use OpenLayers (which can overlay other layers on top of Google
tiles) and grab the code from my "gutters" sandbox.  A working example that
trims tile "gutters" is here:
http://dev.openlayers.org/sandbox/tschaub/gutter/examples/gutter.html

(This handles more tile edge artifacts than just the bleeding filled symbol
problem.)

Tim