Marius,
thanks for the suggestion. I don't know if shapely supports
re-projection of geometries or has a simplify algorithm, which I will
both need. There could be some other functions of GDAL/OGR that I might
need in the future as well. So in principal I'd prefer to stick to GDAL.
armin
On 16/03/2011 01:35, Marius Jigmond wrote:
Armin,
Not sure if this would be straightforward in GDAL but you might want to
consider a combination of GDAL + Shapely
(http://gispython.org/shapely/docs/1.2/manual.html#cascading-unions).
What you're trying to do is spatial analysis not directly implemented in
GDAL. Shapely requires that you're working with Cartesian coordinates.
The upside is that it has WKT/WKB support for direct loading into
PostGIS.
-marius
On Wed, 2011-03-16 at 01:08 +0100, Armin Burger wrote:
Hi all
I would like to catalogue shapefiles scattered over lots of directories
of the file system and store retrievable information of the shapefiles
in a PostGIS layer. Extracting parameters like extent, projection,
fields, etc works very fine with GDAL's Python bindings.
But I would also like to store a sort of "footprint" of the whole
shapefile as a geometry object since the extent is a bit coarse
geographic representation of the shapefile.
So far I have no better idea than eg. for polygon shapefiles looping
through all features, applying a Union function on them. And at the end
trying to use the Simplify method on the resulting polygon that will be
used as the footprint.
This is for sure not very efficient for larger shapefiles with lots of
records. And for line and point shapefiles I still don't have a clue how
their records could be represented by an enclosing polygon (maybe the
Boundary functions does something like this...).
Any ideas how this footprint generation could be achieved in a feasible
way using GDAL/OGR Python?
Cheers, Armin
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