Localized guided liquid simulations in bifrost
Michael Bang Nielsen, Konstantinos Stamatelos, Adrian Graham, Marcus Nordenstam, Robert Bridson · 2017
A guided liquid simulation [Nielsen and Bridson 2011] re-simulates a thin surface layer of an existing liquid simulation at higher resolution, or simulates just a thin layer near the surface of an animated input sequence produced e.g. by hand or by spectral wave methods. The movement of the simulated surface layer is guided by the underlying animation and this technique has been used to achieve high surface detail and art-directed water effects on several movies including "Hobbit - The Desolation of Smaug" and "Tintin - Secret of the Unicorn". Despite the successful application of guided simulations in production, the method as originally proposed requires a fair amount of manual setup time and can be computationally costly in scenarios where the area of focus (such as a moving ship) covers a large and non-regular area over time. In this talk we present an outline of a novel set of algorithms facilitating localized guided simulations, where the guided simulation takes place only within a - possibly animated - local region specified by the user. We have implemented our algorithms in Autodesk Maya's procedural Bifrost framework and integrated them with Bifrost's adaptive FLIP solver. We demonstrate with several examples the benefits of our approach in terms of computational efficiency and ease of use. Additionally our tool was utilized by Moving Picture Company (MPC) to create high resolution art-directed water simulations on Pirates of the Caribbean - Dead Men Tell No Tales.