[gdal-dev] gdal utilities question

[Dennis Burgess]

I have been using the GDAL utilities.  But ran into a snag.  We create
KML overlay files, basically KML file that geolocates a PNG on google
maps.  This PNG is a vector image as well as can have 1 or two colors
other than the transparent background.    We used gdal to convert this
to a GEOTIFF using the gdal_contour and this work quite well, its
ignores the colors for the most part, as all we want is a poly of the
colored areas, don't care about what color.  gedal_polygonize, sees all
colors and seams much more rough.  

 

in both cases, we generate a KML shapefile, but it appears they create
line entries vs polygons.

 

We also use ogr2ogr to simplify the KML as well.   Can anyone give me
some better method to get a pologyon for only the colored areas ,
ignoring changes in color.?

 

Dennis Burgess, 

 

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