[Mapserver-users] Using a polygon instead of a bounding box?

[Timothy Rupe]

I'm using data from multiple sources, some of which are more accurate
than others.  When viewed at a national level they are all equally
accurate, but when viewed at a county level or lower, I want the
better (local) data sources to "override" the poorer (national) data
sources.  My problem is that these local data sources are not
necessarily rectangles, but can be arbitrary polygons.

I would like mapserver to be able to query my coverage database, get
the bounding polygons for each data source I need, and then create a
layer based on this patchwork.  Any locations not covered by the
higher accuracy local data would be filled in with the national data. 
Optimally, this would be transparent to the user, and would appear to
be just another layer served by mapserver.  Is this possible?  If not,
any ideas or workarounds?

Thanks,

Timothy Rupe
Programmer
USGS Mid-Continent Mapping Center