Wave Animation with John Clark

In the third of a series of production diaries, John Clark talks about what it takes to craft the digital waves in Sony Pictures Animation's 3D-animated feature, Surf's Up.

by John Clark

First of all what are waves? Well, from a surfer's perspective, waves are essentially a water surface on which we can ride our surfboards. Waves begin their lives far out to sea when ocean storms begin to generate high winds that disturb the ocean surface. If the winds perpetuate long enough, and blow hard enough, then waves of tremendous size can be created. These waves travel across the ocean, sometimes thousands of miles away before they reach a shore upon which they break.

Transition from animation control rig to final quality render. The left side represents the model and controls intercut with animations; final composite image showing white water, lip spray and board spray effects. All artwork © Sony Pictures Animation.

Why do they break, you ask? Because as waves reach shallower water, they begin to "feel" the bottom and friction slows them down. When they reach an area where the bottom rises up very quickly (such as a beach or a reef), then the wave slows down very quickly, and the wave energy below the surface causes the wave to rise higher and higher, until... you guessed it, the wave becomes unstable and it breaks. And if you're lucky, you can catch the wave at the very moment it breaks, and ride it to the beach, dude.

Shows wave surface without dynamic effects.

Now we've talked about real waves, but what about CG animated waves? Well animating waves has been and will always be a complicated matter, and the very notion of animating a realistic "surfable" wave conjures a barreling pit of potential difficulties. Add in the idea that the wave must behave as a character - pitching, throwing, swelling, crashing, barreling, closing-out, pinching, backing off, opening up, flattening out, walling up and any other action and condition a surfer might encounter on a single ride -- and wow! Now we've really got our work cut out for us. My job on Surf's Up was to think through all these potentials, create the wave animation, and then to design, block, and layout the subsequent surfing shots with as close to final timing and action as possible. I would then pass the final-animated locked wave, and the rough-animated surfers on the wave to the surfing animation team for final character animation on the surfers.

Animation Control Rings: each ring can be turned independently to evolve the weave animation along the wave; Wire frame model of wave surface without shading or high frequency detail.

My approach to animating a wave for a shot was always multi-fold and started with laying out a ton of groundwork prior to every sequence. By groundwork, I mean water work, and that meant teaming up with the directors to get a good sense of the character of the waves in each sequence, i.e. How stormy is the weather? How big are the waves here? How much skill should the surfer need to ride the waves? Is the surf powerful and tubing? Or is it weak and mushy? Are the wave breaking left or right? Or both? How long are the longest rides? I also needed to know the story in order to help solve how the events could unfold in the terms of surfing, and in the surfing environment. We called that "keeping it real." Often the directors would ask me how the action would unfold in a "real" surfing environment, and I would call upon my 25 years of surfing experience that included surfing in contests and surfing big waves around the world.

White water and lip spray elements only.

Once I had a good sense of what was called for creatively, I would approach the technical side of things and begin to think of the physics involved: How fast should this type of wave be moving forward? How fast should it break down the line? What's the speed of a surfer in the tube? How can I shape the wave to get the length of rides that are required? Is there enough room in the environment, or will we can to cheat space, or add in a cut? What is the camera speed here? What kind of camera are we using: water cam, jetski cam, telephoto from the beach?

It is here that I would open Maya, import a Wave Rig and begin animating. Yes, the wave has a character rig like every other character, complete with a list of controls and attributes. The main controls for the wave were a series of concentric rings in a row across the center of the flat wave surface. The wave surface itself begins as a flat nurbs plane. Rotating each ring would drive blend shape curves through the shape-stages of a breaking wave, from rising to peaking to crashing and dying. I also used my wave knowledge, and a ton of reference to help model these blend shapes and give the waves the most authentic contours I could achieve.

Wave Render: Water only.

In addition to the control rings, I had a number of attributes, which enabled me to greatly alter, and sculpt the wave shape and size. Some of the basic attributes under my control were the throw of the lip, the trough depth, the wave face height, the slope of the shoulder of the wave, how much the wave collapses, the height of the wave back, the thinness of the lip, the noise on the lip, and the height and width of the wave. Adjusting all these attributes enabled me to create our three basic wave types that appear in the move: The Pipeline wave, the Mavericks wave and the Spilling Breaker wave. They also helped me create special conditions in the wave animation, such as a "close out" or an "air ramp section" (a section of the wave that slopes perfectly for launching an aerial maneuver).

Wave Render: Water + foam and spray elements.

So back to Maya. I would animate the wave according to its wave type, and the size and length that we predicted would be required for the sequences, and so I began to build a library of generic wave animation. I very soon built a library of over 25 fully animated waves from which I could choose as a starting point for each shot in a sequence. For example, I would pull in a "Mavericks 30ft Left" when animating a contest shot toward the end of the film, or I would bring in a 6ft Pipeline Left to use on Z's Beach for a perfect tube ride. I would then position the wave in the island environment, and begin to customize the wave to the requirements of the shot. I chose starting points for the wave that made sense for the environment, meaning that the wave would begin breaking at a point in physical space that made sense for the shape of the island and the wave type. We tried to maintain consistency with where the waves broke throughout the film, which added to the feeling of being at a real beach with real waves. In this movie, you can look around and know where a character should sit in order to catch a wave. I would next import a surfboard and a surfer, position them relative to the wave as required for each shot, constrain them to the animated wave and block out the surfing action and the cameras to the satisfaction of the directors.

Wave Render: Water + foam and spray elements + characters.

Often I would setup one wave for a series of shots, block the surfers' actions - from paddling to catching the wave, to standing and riding. I would then create the numerous camera angles that we needed. This kept the action flowing in real time as guided by the speed of the oncoming wave. Blocking the action this way constrained us to "keeping it real," so the audience will always have the feeling of being in the water with an oncoming wave. This is a very different approach to traditional animation where time could be cheated at will. Instead we chose to make time and space dictate action, and adjust speed in a cinematographic way --by changing the camera speed. This choice ensures that the surfing will feel real, consistent and intrinsically "right" throughout the entire movie.

Needless to say, I was constantly inundating myself with reference, and that meant watching surf videos with a stop-watch. My online account with Surfline was essential, because many surf movies on DVD are shot high-speed, thus making it difficult to judge actual surfing speed. Surfline has a library of realtime video. However, we made good use of the high-speed photography techniques that the best surf filmmakers use in their films, thus I was often animating from 96fps up to 192fps. We even added speed ramps and step-framing that simulated many of the cool effects from the best surf movies. Once again "keeping it real."

Render of a typical “pipeline” wave with all the elements composited.

So there you have it. Wave animation in a rather large nut-shell. The job was a pleasure for me to do, as it combined two of my life's passions: surfing and animation -- and I really hope it gets you inspired to do both. So enjoy Surf's Up, and get out there a catch a wave!

Radically yours,

John Clark

John Clark is a technical animator at Sony Pictures Imageworks. Having just completed working on Surf's Up as the Wave Animation lead, Clark currently is contributing his talents to Cloudy With a Chance of Meatballs. Clark has worked in commercial film production for more than 14 years, creating scenic art and practical effects before moving into digital animation and visual effects. He joined Sony Pictures Imageworks, having been the visual effects supervisor for the award-winning digital production house Motion Theory in Venice Beach, California, where he garnered commercial credits with campaigns for HP, Budweiser, Toyota, Direct TV, Mervyns, Johnson & Johnson, Mazda, Nike, Fox, ESPN, EA Sports, Met Life and Cingular. Clark also helped create music videos for The Used, Papa Roach, R.E.M., Less Than Jake, Velvet Revolver and Beck. Clark's awards for animation and vfx include: five AICP awards, International Art Directors Silver Cube and Gold Cube, and multiple Telly awards, along with having had two animation pieces accepted to the SIGGRAPH Computer Animation Festival. Clark concurrently is teaching Dynamic Effects Animation at the Gnomon School of Visual Effects in Hollywood. He is a graduate of the University of Central Florida. Originally hailing from the Cocoa Beach area of Central Florida, Clark now is living in Culver City, California.