Aspect — the downslope compass bearing via Horn's method (gdaldem's aspect algorithm, cellsize-free like GDAL's own — it assumes square pixels): 0=north, 90=east, clockwise. Flat pixels (no gradient) → -1 (gdaldem's flat sentinel).
Aspect — the downslope compass bearing via Horn's method (gdaldem's aspect algorithm, cellsize-free like GDAL's own — it assumes square pixels): 0=north, 90=east, clockwise. Flat pixels (no gradient) → -1 (gdaldem's flat sentinel).