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Abstract:
Large, 3D ice formations such as icicles exhibit a high degree of geometric
and optical complexity. Modeling these features by hand can be a daunting
task, so we present a novel physically-based algorithm for simulating this
phenomenon. Solidification is usually posed as a so-called `Stefan problem',
but the problem in its classic form is inappropriate for simulating the ice typically
found in a winter scene. We instead use the `thin-film' variant of the
Stefan problem to derive velocity equations for a level set simulation.
However, due to the scales involved in the problem, even an adaptive grid level set
solver is still insufficient to track the tip of an icicle.
Therefore, we derive an analytical solution for the icicle tip and use
it to correct the level set simulation. The results appear to be in
agreement with experimental data. We also present a physically-based
technique for modeling ripples along the ice surface that alleviates the
need to explicitly track small-scale geometry. To our knowledge, our
approach is the most complete model available, and produces
complex visual phenomena that no previous method has been able to capture.
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