1. A method for synthesizing a photomask data set from a given target layout, comprising the steps of: a) providing a set of target polygons for said target layout; b) fitting a smooth curve to a target polygon of said set of target polygons, the curve having a set of etch-target points; c) moving the etch target points according to a model of an etch process to produce a set of lithography-target points; and d) synthesizing a photomask data set based on a model of a lithography process and the set of lithography-target points.