  We elucidate the basic physical mechanisms responsible for the
quantum-classical transition in one-dimensional, bounded chaotic systems
subject to unconditioned environmental interactions. We show that such a
transition occurs due to the dual role of noise in regularizing the
semiclassical Wigner function and averaging over fine structures in classical
phase space. The results are interpreted in the novel context of applying
recent advances in the theory of measurement and open systems to the
semiclassical quantum regime. We use these methods to show how a local
semiclassical picture is stabilized and can then be approximated by a classical
distribution at later times. The general results are demonstrated explicitly
via high-resolution numerical simulations of the quantum master equation for a
chaotic Duffing oscillator.
