  Simulating the radar illumination of large scenes generally relies on a
geometric model of light transport which largely ignores prominent wave
effects. This can be remedied through coherence ray-tracing, but this requires
the Wigner transform of the aperture. This diffraction function has been
historically difficult to generate, and is relevant in the fields of optics,
holography, synchrotron-radiation, quantum systems and radar. In this paper we
provide the Wigner transform of arbitrary polygons through geometric transforms
and the Stokes Fourier transform; and display its use in Monte-Carlo rendering.
