Updates
These maps are based on several terrain parameters that capture most of the variability: profile curvature, tangential curvature, slope gradient, annual solar radiation, and truncated flow-density.

SFREC-terrain_classification_003: 3-class terrain groupings

SFREC-terrain_classification_004: 4-class terrain grouping

 
First Attempts
The were based on a flow-accumulation (r.watershed) and quick estimate of annual beam radiance. The artifacts were caused internal casting of FCELL to CELL in the updated version of r.watershed's MFD flow-routing algorithm. Multiplying elevation data by 100 first solves these problems. In addition, the strong influence of the active channel can be minimized by setting an (empirical) upper bound to the flow accumulation map.

SFREC-terrain_classification_002: Flow accumulation and solar radiation; convergence=5 -- PAM unsupervised classification.

SFREC-terrain_classification_001: Flow accumulation and solar radiation; convergence=1-- PAM unsupervised classification.