Table 3
Parameters for a GTP run.
 Objective  Generate realistic or aesthetic terrains  Function set  Functions from Table 1, all operating on
matrices with float numbers  Terminal
set  Terminals from Table 2 chosen randomly  Selection and fitness  Decided by the designer accordingly to
desired terrain features or aesthetic appeal  Population  Fixed size with 12 individuals; initial
depth limit 6; no tree size limits; random initialisation  Parameters  If 2 individuals are selected: 90% subtree
crossover and 10% mutation; if just one individual is selected: 50% mutation
(without crossover)  Operators  Three mutation operators are used with equal
probability: (1) Replace mutation where a random node is replaced with
a new random tree generated by the grow method; (2) Shrink mutation where a random subtree (S) is chosen from the parent tree and replaced by a
random subtree of S; (3) Swap mutation where two random subtrees are
chosen from the parent tree and swapped, whenever possible the two subtrees
do not intersect. One crossover operator is used: subtree crossover where random nodes are chosen from both parent trees, and the respective
branches are swapped creating two offsprings  Termination  Can be stopped at any time by the designer,
the “best” individual is chosen by the designer 

