Generating 2D and 3D coordinate systems using geometric ray-tracing on
potential function solutions of Laplace's equation is a viable
approach. Because of certain properties of potential functions,
ray-traced coordinate systems are guaranteed to be orthogonal.
Importantly, these coordinate systems are appropriate for 3D
Riemannian wavefield extrapolation, and can be applied in numerous
scenarios, including wave-equation migration directly from an
undulating 2D topographic surface, and VSP imaging from deviated wells.