[[File:Levelset-mean-curvature-spiral.ogv|thumb|Video of spiral being propagated by level sets ([[curvature flow]]) in 2D. Left image shows zero-level solution. Right image shows the level-set scalar field.]]
The '''Level-set method''' ('''LSM''') is a conceptual framework for using [[level set]]s as a tool for [[numerical analysis]] of [[Surface (topology)|surface]]s and [[shape]]s. Even though [[Euler method|Eulerian methods]] have their uses, like approximating unknown curves, LSM can perform [[Numerical computation|numerical computations]] involving [[curve]]s and surfaces on a fixed [[Cartesian grid]] without having to [[Parametric surface|parameterize]] these objects.<ref>{{Citation |last1 = Osher |first1 = S. |last2 = Sethian |first2 = J. A.| title = Fronts propagating with curvature-dependent speed: Algorithms based on Hamilton–Jacobi formulations| journal = J. Comput. Phys.| volume = 79 |issue = 1 |year = 1988 |pages = 12–49 |url = http://math.berkeley.edu/~sethian/Papers/sethian.osher.88.pdf |doi=10.1016/0021-9991(88)90002-2|bibcode = 1988JCoPh..79...12O |hdl = 10338.dmlcz/144762 |citeseerx = 10.1.1.46.1266|s2cid = 205007680 }}</ref> Importantly, LSM makes it easier to perform computations on shapes with sharp corners and shapes that change [[topology]] (such as by splitting in two or developing holes). These characteristics make LSM effective for modeling objects that vary in time, such as an [[airbag]] inflating or a drop of oil floating in water.
[[Image:level set method.png|thumb|right|400px|An illustration of the level-set method]]
