This shot follows a classic FOOH approach — I developed the concept, captured the plate on my phone, and 3D tracked the footage before moving into Houdini to build the VFX.
The main focus of this piece was to explore more advanced control of velocity fields and custom forces, while also pushing my whitewater workflows beyond standard FLIP tank setups.
The Vortex:
A key challenge was controlling the vortex behavior, keeping the liquid contained within the force while maintaining a clean shape, without making the force so strong that it prevented natural breakup and escape.
The vortex forces were fully animated, initially driving the liquid upward, and, after the magic was done, reversing it to pull it back into the manhole. To support this motion, particles were managed through groups with distinct lifecycles: particles settling on the shouldn't age, while particles within the vortex were continuously recycled to maintain a stable and dynamic flow. As the motion transitioned to pulling the liquid back, particle aging was disabled to ensure a cohesive return.
