A method for modifying an upper layout for an upper layer of an IC using information of a lower layout for a lower layer of the IC, the method including 1) receiving the upper layout containing features and modifications to features, 2) producing a density map of the lower layout having geometry coverages of sub-regions of the lower layout, 4) selecting a feature in the upper layout, 5) retrieving, from the density map, the geometry coverage of a sub-region below the feature, 6) determining a vertical deviation of the feature using the geometry coverage, 7) determining an alteration to the modification using the vertical deviation, 8) applying the alteration to the modification, and 9) repeating for all features. In some embodiments, the upper layout is designed using a library of pretabulated models, each model containing a modification to a feature calculated to produce a satisfactory feature on a wafer.