Abstract: For modifying a zone of a surface having an original shape, outer constraints are defined at boundaries of the zone as continuities Gk along at least part thereof. Inner constraints Gn are defined as points or curves to be crossed by the zone when modified. An amount of deformation is defined in each point of the zone as a result of a resilient deformation of a generalized infinite thin planar plate in equilibrium, respecting the outer and inner constraints. The modified zone is generated as a surface resulting from a result of an application of the resilient deformation to the original shape in the zone and connected to the unmodified portion of the surface.