1. A method for calculating design parameters D j , j=1,. .. , M of a progressive spectacle lens design on the basis of a predetermined design polygon, the method comprising: specifying a point P Design within the design polygon, wherein the point P Design defines the spectacle lens design; and determining a value D j (P Design ) of each design parameter D j , j=1,. .. , M, of the spectacle lens design at the point P Design by an interpolation of one or more predetermined values D j (P Corner ), j=1,. .. , M at respective corner points P Corner and, optionally, of one or more predetermined values D j (P Addition ) of the design parameter D j at least one additional point P Addition , wherein each point P within the design polygon defines one design that is characterized by design values D j (P), predetermined design values D j (P Corner ), j=1,. .. , M of the design parameters characterize the design at the respective corner points P Corner of the design polygon, predetermined values D j (P Addition ) of the design parameters characterize the design at the at least one additional point P Addition within the design polygon, and M designates the number of design parameters.