I classified my raster-DHM into elevation levels using colormap. Its not a "real" classification, just a colormap. So I can't vectorize the classes to get polygons for every class.
What's the best way, to classify and vectorize a raster? The Rastercalculator? How to use it, if I want to classify my DHM in elevation gradation like: 1000-1200m; 1200-1400m?