The term surface aberrations refers to features of the OF response to DVs, features of the topology, that make it difficult for optimization algorithms. Finding the optimum of an unconstrained quadratic surface is a trivial exercise. However, for many applications several types of OF features cause difficulty for the algorithm. These are easily visualized in the three dimension of a 2-D application (OF response to DV1 and DV2) but translate to 1-D and N-D applications. The following illustrations show the 3-D net and/or 2-D contour map patterns.