500

 -Hip
 Knee
 400 -Ankle



 "E
 u 300




 S200
 U.



 100




 0
 0 5000 10000 15000 20000 25000
 Function Evaluations

Figure 4-1. Outer-level optimization objective function fitness value convergence for
 synthetic marker data with random continuous numerical noise to simulate
 skin movement artifacts with maximum amplitude of 1 cm, where the best
 fitness value among all nodes is given for each iteration.