When was the last time you ran a fluid simulation for your visual effects shot and when it was done you sat back and thought “Perfect”. I’ll bet it’s been a while, if ever. CG Fluids are notoriously hard, and the reason why is best described in this paragraph from FusionCIS:
CG fluid, especially “SPH” fluid (smoothed particle hydrodynamics), suffers from inaccurate physics at the microscopic level, at the scale of individual particles making up the fluid. Even when simulating with very large particle numbers, this becomes a major problem wherever the fluid becomes splashy since it forms thin sheets and strings — or rather, it should form thin sheets and strings, like we see in real water. Hi-speed macrophotography of fluid spashes classically show how delicate, impossibly thin and continuous sheets of fluid fly thru the air and stay coherent for prolonged periods. These produce tiny droplets and hair-like strings of fluid from their margins but otherwise hold together for a long time, before they eventually and suddenly burst apart. CG fluids on the other hand always break apart immediately, forming very unattractive and distinctly un-real cheese-like holes and webbing, never holding together in thin sheets.
So what do you do? Most people tend to try and hide the effect with careful camera tricks, motion blur, or just add more particles. A new technology from FusionCIS called “Smorganic” can fix this by closing the holes created during the simulations, and create amazing new life-like simulated results, as shown in the image above of “honey” pouring over a sphere:
The image below is a render of a simulation of pouring “honey”, where we’ve set smorganic to disallowo any holes in the fluid. The results show the smoothness of the resulting meshes despite the high-spec, high-refractive nature of the shader and lighting, and despite a hard impact with a rigid body.
Hit their website for more pictures and sample movies.
