I have a reclassified slope raster with 3 values in band 1. My problem is that I want to polygonize this layer, but the surface is so irregular with a lot of plots in terraces and because of this it becomes in a vector layer with infinite polygons.
What can I do to clean up the raster layer to obtain bigger polygons of slope?
Smooth the slope raster first. You can use a focal mean on the raw slope raster and then classify it, which will clean up some of the "noise".
You can clean up the classified raster using a focal majority. Alternately, you could use a sieve approach to establish a minimal mapping unit for your classified raster. Here are some details on sieve.
Using sieve filter in ERDAS Imagine and/or ArcGIS for Desktop?
How to generalize and vectorize a LandUseClassification raster file?
