[FWTools] Clipping based on polygons

[Frank Warmerdam]

Travis Kirstine wrote:
> Hi All,
> I am fairly familiar with the command line utilities included with FWTools
> and would like to automate some of tasks I perform via python.   What I
> would like to do is clip shapefiles and or rasters based on a existing tile
> index. I have done a little python scripting in the past but would
> appreciate some direction.

Travis,

I would advise you to review some of the scripts in

    http://www.gdal.org/srctree/pymod/samples

and

    http://www.gdal.org/srctree/pymod

Do you want to clip the actual geometries in a shapefile to some predefined
tile boundary or just select all features with geometries touching the tile
area.  Clipping is a bit more involved ... you would need to use the
ogr.Geometry.Intersection() method on the geometries and a tile rectangle.

I think rel.py could be helpful in writing a script to do spatial clipping.
Are you wanting to clip to a rectangle or to a polygon?

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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