The gradational filter redefines the null nodes outside a clipped region by computing the distance to the closest defined node and multiplying the g-value for the closest defined node be a scalar based on the distance to that node.  For example, if the closest distance from a null node to a non-null node is very small, the null node will be reassigned a value that is very close to the closest defined node.  Conversely, as the distance increases, the reassigned value will decrease.

Pre-Filtering:  If desired, node values below a specified threshold can be set to null before the gradational filtering takes place.

Distance: This setting defines the lateral width of the gradation.