Fast Marching and Velocity Extrapolation
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We study the `Fast Marching method <https://math.berkeley.edu/~sethian/2006/Explanations/fast_marching_explain.html>`_ for computing signed distance fields. A more accurate version is described `here <http://physbam.stanford.edu/~fedkiw/papers/stanford2004-07.pdf>`_ in Section 2.2.

Fluid velocities are extrapolated outside the liquid region using a similar
method, as described `here <https://www.sciencedirect.com/science/article/pii/S0021999198960909>`_.