Terrain
What a digital elevation model says about a cell: how steep it is, which way it faces, and how broken the ground around it is.
Terrain tools read a 3 x 3 window of a digital elevation model and describe its center cell: slope, aspect, and hillshade by Horn's method, and the terrain ruggedness index, topographic position index, and roughness. GIS analysts, hydrologists, and site planners use them to check a cell by hand or to test the numbers a GIS reports. Start with slope, aspect, and hillshade. One pitfall: on a grid in degrees, a cell is narrower east to west than north to south away from the equator, so its size must be corrected for latitude, which the slope tool does.
I want to find the slope, aspect, and hillshade of a cell
- Slope, aspect, and hillshade
Slope, aspect, and hillshade for the center of a 3 x 3 elevation window by Horn's method, with the cell size corrected for latitude on a degree-based grid.
I want to describe how rugged the ground is, and whether a cell is a ridge or a hollow
- Terrain ruggedness and position
The terrain ruggedness index, topographic position index, and roughness for the center of a 3 x 3 elevation window.