Systems, methodologies and technologies for the analysis and
transformation of integrated circuit layouts using situations are
disclosed. A method for transforming an integrated circuit (IC) layout
includes recognizing shapes within the IC layout, identifying features
for each of the shapes and extracting situations for the respective
features. Extracted situations can be used to improve optical proximity
correction (OPC) of the IC layout. This improved OPC includes extracting
the situations, simulating the situations to determine a set of the
situations identified for modification based on failing to satisfy a
desired OPC tolerance level, modifying the set of situations to improve
satisfaction of the desired OPC tolerance level, and reintegrating the
modified set of situations into the IC layout. Extracted situations can
also be used to improve aerial image simulation of the IC layout. This
improved aerial image simulation includes extracting the situations,
simulating a subset of the situations to determine aerial images of the
subset, and tiling the subset of situations to form a larger aerial
image. Extracted situations can further be used to improve density
analysis of the IC layout. This improved density analysis includes
extracting the situations for a window of the IC layout, removing overlap
from the window based on the extracted situations, calculating a density
for each of the situations, and calculating a density for the window
based on the density for each of the situations.