1. A method for implementing optical rule checking (ORC) to identify and quantify corner rounding errors, the method comprising: using a computer for: receiving ORC corner rounding data based on established ground rules; determining a simulated shape for a semiconductor device feature produced on a wafer, the simulated shape based on a designed shape for the semiconductor device feature; selecting a corner feature associated with the designed shape, and drawing one or more triangles at the selected corner feature; for each drawn triangle, determining the presence or absence of an intersection between the triangle and the simulated shape, wherein a degree of corner rounding is determined by a pair of successively sized triangles for which one of the pair intersects with the simulated shape and the other of the pair does not intersect with the simulated shape; determining an approximate corner rounding; and comparing the determined approximate corner rounding with the ground rule based ORC corner rounding data for the designed shape to determine whether the simulated shape results in a corner rounding rule violation.