A few different ways to handle fish animation
On our most recent production, Expedition Reef, I was tasked with figuring out how to populate our CG coral reefs with thousands of fish.
With strong guidance from Bart Shepherd (director of Steinhart Aquarium) and Luiz Rocha (curator of ichthyology), we chose about 30 species of fish to populate our opening scene which takes place at Devil's Point in the Phillippines.
After modeling the fish we needed, and texturing them with the help of Shauna Lacoste, I set up a tool in Houdini that would allow me to apply a generic rig dynamically to any of the fish, which sped the agent baking process up nicely. Here is a look at our fishy cast of characters.
I used Houdini's crowd/agent system for the bulk of the background schools of fish. Here is a look at several of the behaviors I developed for these fish.
Once you fill a scene with a bunch of these, the sheer complexity of their composite movement hides a lot of the imperfections that you would see if you really focused on a single individual. In fact these fish are all just rigged with a single spine which is animated procedurally using CHOPs in Houdini. The speed of the animation cycle is dynamically increased or decreased based on the speed of the particle in the simulation.
Using houdini for all the fish animation was a departure from a show we completed in 2014 where I used Maya for the bulk of the fish animation. I was able to get a more character-animator-friendly rig built in maya which meant more hand animation work, and less 'free' procedural animation, but I think that actually gives it more nuance and character really. The truth is though for Expedition Reef, I had so many fish on my plate for that show that I was focusing more on mass production than on individual nuance, so procedural animation and agent schooling systems was a godsend. Anyway, here is a look at the fish rig I built in Maya back in 2014 for animation rock fish.
And here's a sexier looking render of that same rockfish that I had made for some promotional video when we released the show back on 2014.