Three images with equal extent along their respective major axis, from left to right: a Gaussian; a crescent model; a ray-traced image from a general relativistic magneto-hydrodynamics (GRMHD) simulation of a black hole shadow and accretion disk. Model visibility amplitudes along the major axis of each source as a function of (u, v) distance, after flux and size normalization, show identical behavior at short baseline length but diverge at longer baseline length: the Gaussian in black; the crescent in blue; and the GRMHD simulation in red.