Let’s dive deeper into the new topographic derivatives we just added to GeoPard.
Relief Position is defined as the difference between a central pixel and the mean of its surrounding cells. In other words, spots with negative values mean field lowland, spots with positive values - field highland. You can have a hilltop in a “low” elevation that has very different soil properties than a mid slope or depression. Elevation, slope and aspect cannot show this. Relief position is calculated in meters.
Slope is the angle of inclination to the horizontal. Usually, it is calculated in degrees or percent slope. GeoPard does that in percent.
Ruggedness is defined as the mean difference between a central pixel and its surrounding cells. In other words, ruggedness describes the slope in absolute numbers (in meters) for every particular location (pixel).
Roughness is the degree of irregularity of the surface. It’s calculated by the largest inter-cell difference of a central pixel and its surrounding cell. In other words, it measures the maximum absolute value of the slope in meters for every location (pixel).
These four topographic derivatives reflect the slope details but in a bit different flavour.