  The physical world consists of spatially varying media, such as the
atmosphere and the ocean, in which light and sound propagates along non-linear
trajectories. This presents a challenge to existing ray-tracing based methods,
which are widely adopted to simulate propagation due to their efficiency and
flexibility, but assume linear rays. We present a novel algorithm that traces
analytic ray curves computed from local media gradients, and utilizes the
closed-form solutions of both the intersections of the ray curves with planar
surfaces, and the travel distance. By constructing an adaptive unstructured
mesh, our algorithm is able to model general media profiles that vary in three
dimensions with complex boundaries consisting of terrains and other scene
objects such as buildings. We trace the analytic ray curves using the adaptive
unstructured mesh, which considerably improves the efficiency over prior
methods. We highlight the algorithm's application on simulation of sound and
visual propagation in outdoor scenes.
