1. A method comprising: identifying a mapping assigned to a first patch by one or more processor-based devices; propagating the identified mapping to a second patch to generate a propagated mapping by the one or more processor-based devices; perturbing the propagated mapping to generate a perturbed mapping by the one or more processor-based devices; and assigning one of the propagated mapping and the perturbed mapping to the second patch by the one or more processor-based devices.