[email protected] wrote:
Hello,
I need to crop an image based on a polygon from a shapefile.
Could not figure how to do it so I used gdal_translate and I specified
the extent of the shapefile like this
gdal_translate -projwin -428734.998712 20337 1.497532 -387578.449250
172036.180727 EstMtl.img rssMtl.img
But the polygon is irregular. So the new image contains the region I
need with some extra. From this new image Is there a way to assign
"nodata" to pixels outside the irregular polygon?
Or maybe there is a way to crop an image from an irregular polygon?
thanks
Steve,
You can use the gdal_rasterize command to burn a nodata value to all
pixels outside a target polygon.
eg.
gdal_rasterize -burn 0 -i -l polygon polygon.shp rssMtl.img
Note the -i flag meets to invert - that is assign all pixels outside
the polygon instead of all the pixels inside the polygon.
Docs at:
http://www.gdal.org/gdal_rasterize.html
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, [email protected]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent
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