 This representation is efficient in terms of storage, formula_14 and relatively efficient in terms of access queries, formula_15 An advantage of the level method on octree data structures is that one can solve the partial differential equations associated with typical free boundary problems that use the level set method.The CASL research group has developed this line of work in computational materials, computational fluid dynamics, electrokinetics, image guided surgery and controls.The run-length encoding (RLE) level set method, introduced in 2004, applies the RLE scheme to compress regions away from the narrow band to just their sign representation while storing with full precision the narrow band.