Hi all, I was writing to enquire about the status of the "8CONNECTED=8" option in the Polygonize function of GDAL 1.8. I would expect that this option joins all pixels of equal value that are diagonally adjacent into a single polygon.
However, with the following raster dataset (see http://i.imgur.com/jdUla.png) I receive two polygons in my output shapefile (see http://i.imgur.com/CZWMU.png ). For a copy of the raster, see http://dl.dropbox.com/u/6732375/mish9000.img.zip I am calling polygonize from GDAL's python bindings, which reports itself as "GDAL 1.8.0, released 2011/01/12". My code looks like: gdal.Polygonize(tmprasterband, tmprasterband, shapefile_polygons_layer, 0, ["8CONNECTED=8"]) Is this the expected behaviour or a bug? Can I modify my call to polygonize to get the desired behaviour? If not, how would I merge multiple polygons with the same attribute value (an id number) into a single geometry? Thanks for your help, Francis Markham
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