The easiest and most intuitive way of describing the ELEVATION GRADIENT component is in terms of color, which we'll use here, but the same concepts apply to the percent and bump versions.
ELEVATION GRADIENT assigns colors based on the elevation values of a linked bump texture. You can
think of this as "coloring" a topographical map, based on elevation. The Shell Position 1 to -5 and Shell Value 1 to -5 parameters define the colors assigned by you to each elevation. For a given shell position,
which you can think of as an elevation, any part of the bump texture that has the same elevation will be assigned the corresponding shell color. For the blending between elevations, you can link the Blend Function parameter to a generator or let it default to a linear blend. You can set the number of shell positions and values from 2 to 5.
When the Enable Clamps parameter is set, the elevation values and colors remain in the same order (that
is, from one to five). In other words, Shell Value 1 (which corresponds to the lowest elevation) will never appear above Shell Value 2 (which corresponds to the next higher elevation). This is so, even if Shell
Position 1 was given a higher elevation level than Shell Position 2. Rather, the shell position will be clamped to a lower value than the next elevation level. When Enable Clamps is not set (checked), the
order of the shell values depends on the values given to the shell positions.
