Polygon buffer?

[Steve Lime]

Jason: MapServer does support this, either via the CGI or using
MapScript.

MapServer's feature or shape query methods do support distance
computations.
The result set mimics doing a buffer on the selection shape first and
then applying
it looking for intersections/overlap.

Distances are set within the layer to be searched using TOLERANCE and
TOLERANCEUNITS
so you could do something like:

  - select a lake
  - find all boat landings within 500 ft
  - find all state parks within 50 miles
  - find all steams with 1 km

All with one query. I don't have a good example laying around, but it's
easy enough
to setup. Here's a featurenquery example that selects a county and all
quads that
intersect it. If you set layer tolerances for the quad layers being
searched you'd
get what I described above.

Steve

>>> "Sievers, Jason" <jsievers at CO.LINN.OR.US> 12/8/2006 1:27:47 PM >>>
I want to perform a buffer query around a polygon.  I would select a
polygon, then get features from another layer who are within a
specified
distance of the outside edge of my selected polygon.  The only queries
involving buffers I see in the documentation are on points.  I have
looked
briefly at PostGIS and GRASS documentation.  Is the solution possible
in
MapServer? or should I investigate PostGIS, GRASS, or other tools?

Thanks for any help.


Jason Sievers
jsievers at co.linn.or.us