I'm trying polygonize the elevation level 200 m of Europe map from raster GeoTIFF (The raster is projected in EPSG:3120). At first I tried with Raster > Extraction > Contour, but the lines are interrupted in many parts so using lines to polygon didn't convert it well, joining the line at interrupted path. Then I tried with Vector geometry > Polygonize which in some cases created the polygons but in the major part of the map couldn't create polygons. After that I thought to try it directly from raster using at the process toolbox from GDAL > Raster conversion > Polygonize (Raster to vector), this took about 24 hours and didn't finish the process so I canceled.
I'm stuck at this point. The other elevation levels (500m, 1000m, etc) looks fine. Maybe they have less data than 200m. Can someone tell me whats wrong or a solution for this ?