I'm no expert, but I have some thoughts.
A) this really isn't a GDAL issue -- GDAL is about reading ant writing
the data -- you're interested in processing. you might want to look at
the geos lib.
In order to get this profile, I want to do a spatial query on DEM
shapefiles
DEMs are usually gridded data -- a shapefile is odd for this. Is it gridded?
someone gives me a large shapefile, e.g. that of a whole country, I
don't know if computationally it's reasonable to perform a proximity
check on every single feature in the shapefile. I suppose this would
be O(2), which could get quite expensive/long for a microprocessor or
some kind of embedded platform.
yup.
What you need is a spatial index. I think shapelib has one built in --
you load the shapefile, index it, and then these sorts of neighbor
queries are fast. (order logN, I think).
You could also use:
http://trac.gispython.org/spatialindex/wiki/
and there are python bindings for geos and rtree:
http://pypi.python.org/pypi/Rtree
http://pypi.python.org/pypi/Shapely/1.0.11
which may be helpful for prototyping.
What I was hoping to discover is whether shapefiles have some field in
a feature that says what other features share common points.
nope -- they are pretty simple, really.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
[EMAIL PROTECTED]
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