Link to the original event

An inside look on the Making Of of Pixars UP was presented at Gnomon School.

Balloons always fascinated children and adults. Gray Bruins, Supervisor of Effects for the film “UP“, seemed absolutely fond of balloons after his month-long involvement in the research and technology development that enabled Pixar to animate a cluster of roughly 10.000 balloons between the constraints of simulation and the challenge of artistic direction.

Pixar Attracts Too Many

The presentation that was held in the facilities of GNOMON School of Visual Effects attracted a massive amount of people – those who attended former behind-the-scenes presentations know about the often left over pizza pieces – this time, elbow fighting was necessary in order to grab one of the last pizza pieces.
Also, Gnomons usual presentation room for this type of event – a giant greenscreen studio inside the Television Center at Cahuenge Blvd., Hollywood – did not offer enough space for the huge crowd, so the presentation was held in a warehouse facility two blocks east of Gnomon. UP was simply too popular.

As an estimate, somewhere between 600-1000 people showed up to hear Gary Bruins speak. Many of them had never attended any prior Gnomon school events.

The large crowd attracted by Gnomon's presentation - 600 to 1000 people wanted to see the Making of Pixar's UP.

Speed is the Key – Parametric Objects Solve the Balloon Challenge

In the beginning, the effects team was faced with the request from the art department to creat a balloon cluster with 50.000 balloons. After a few tests, it was clear that there had to be actual interaction between the balloons in order to convey a realistic balloon cloud behaviour. With 500 balloons, the simulation showed pretty much what was needed – but the requested cloud should include 50.000 balloons, and using the same algorithm that was used for 500 balloons would simply cost too much time and flexibility.

The effects department stood in front of a wall: The simulation had to be fast enough to allow animators to manipulate the cluster in e.g. a storm and still review it with an acceptable speed; at the same time, the software had to be accurate enough to not let balloons intersect and give them a realistic, simulated behavior. After some tests, the team decided that 10.000 balloons would be enough, since they aimed for a solution that would prohibit the balloons from intersecting (the number 50.000 was an estimate of randomly aligned balloons inside the pear-shaped cluster boundaries, which would intersect).

Using Maya, a powerful Open-Source dynamics simulator named ODE (Open Dynamics Engine, by Russell Smith) and an in-house, standalone-plugin-hybrid called NED, the effects department came up with a solution: Russell Smith’s ODE allowed a dynamics simulation of a ridiculous amount of parametric objects (Gary showcased a test with tens of thousands of balls colliding and rolling around), and after developing a bridge to Maya – namely NED -, this program could be used to simulate the behavior of balloons and integrate this simulation in the production pipeline.

Since balloons are shapewhise closer to pears than to perfectly round spheres, every balloon was outlined by three differently sized, intersecting spheres for simulation purposes. The speed of NED’s calculations based on ODE’s data allowed a seamless transition from simulation to post-applied animation manipulation like force fields. NED was also responsible for the simulation of popping balloons.

Cutting Ropes and Unleashing Balloons

Those who saw UP can remember the scene where Carl, the old man lead character, cuts a rope in order to free the exotic, colorful bird that the villain Muntz is hunting restlessly. Under the pressure of the knife, the rope slowly tears, then rips apart. Interestingly enough, this effect was realized with NED – the effects put together three chains of cyliners and twisted them the same way actual threads are twisted during the process of making a rope. In simulation, these threads were glued together and then fell apart through the simulated force of the knife.
In a rough animation, Gary showcased that there was a simulated twisting, gluing and parting of the rope before the actual shot happened.

Similarly, in the scene where Carl releases the 10.000 balloons from huge cloth covers behind his house, no cloth simulation was used. Instead, the sheets were formed of thousands of digital flat cubes (resembling the look of a polygon mesh but having the functionality of parametric shapes that can dynamically interact). With NED, these flat cubes were holding together and behaving like cloth. Midway in the simulation, the two sheets were glued together for a few seconds and then released the balloons at the moment chosen by the art department.

Clouds and their Resemblance to Spheres

Another development made for UP was the volumetric cloud creation system. Gary explained a workflow in which the artist puts spheres together, can split them up in smaller spheres when detailing the shape, bulge them, grow and shrink them. The spheres are then filled with a volumetric cloud shader – lots of different presets were developed to emulate different kinds of clouds for different scenes and weather situations – and a density map can be painted within the clouds, generating the self-illuminating effect of a shining white cloud.

The clouds were, very well visible in the storm scene, animated with a fluid system.

Round and Square Shapes

From an artistic standpoint, a round and square shape theme is being applied throughout the whole movie. Round shapes stand for change, freedom and adventure, whereas square shapes symbolize stagnation, boredom and despair. While Ellie, Carl’s adventurous wife, is formed of round shapes and colored in a magenta theme, Carl starts of as a round boy but squares up as he grows older. Furniture, forms, image composition – everything is full of symbolism.

As Ellie dies, Carl is surrounded by squares; the light is shining in all the empty spots where Ellie used to spend her time, while Carl is sitting in shade continuously.  Russell, the boy scout that changes Carl’s life, is also quite a round boy. All these effects were used to support the story.

Further Reading:

• Pixar Website: UP
• Riding a flying arm chair (at Pixar headquarters)
• How Pixars House could really fly
• ODE – Open Dynamics Engine
• Making Of: Pixar’s Up
• 15 Minutes behind the scenes of UP

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