I have a DEM raster file of a country. From this, I want to produce a polygon shapefile which only contains the land boundaries of the country.
My idea is to select the parts of the raster which have values greater than 0 (therefore, selecting only the land part, and excluding the LAKES and OCEANS).
The problem is how to convert this to a polygon, with all the inner lakes and the ocean excluded?
I have tried Raster>Polygonize, but I don't really want this, just the boundary of the country excluding the water bodies.