What I've got:
1: A vector-layer with administrative areas of my country
2: A raster-layer with the slope of the terrain of the same country (it is derived from SRTM elevation data with QGIS)
What I want:
A new vector-layer with the 'flat' land of all administrative areas.
How do I achieve this in QGIS?
A) How to extract the area below a certain slope (in the raster-layer)? - The option for rule-based display is not available (maybe this is just there for vector-layers).
B) How to 'intersect' the flat-land-raster-layer(-mask) with my admin-vector-layer?
A) Actually the "Clip to MinMax" with an appropriate set Min- and Max-value (e.g. Min: 10, Max: 100 - or inverse Min: 0, Max: 10.1) does the job. Now I want to use this as a 'clipping-mask' for my vector-layer, but how?