Terrains in Terraform4D are built from Operator Objects, which are grouped as children under a Terrain Object. The Terrain Object evaluates its child Operator Objects in order from the top down, blending each operator with the result of the previous operators, and generates the terrain geometry from their cumulative effects.
By creating any number of Operator Objects and grouping them under a Terrain Object, you can create an infinite number of unique and interesting terrains. The settings of each Operator Object, as well as its position and rotation in space (at least for some of the operators), and the order of the Operator Objects affect the look of the resulting terrain. The result of each operator is blended with the result of the previous operator.
An Operator Object can either be a Generator or a Filter.
Think of the Operator Objects like layers in an image processing application. They contain - or generate - image data (Generator), or alter the underlying image data (Filter). Just like layers in an image processing application, Operator Objects in Terraform4D can be freely rearranged and enabled/disabled.