The Amazing Spider-Man 2

The cinematic adventures of our friendly neighbourhood Spider-Man are well known for their groundbreaking VFX work. With The Amazing Spider-Man 2, Sony Pictures Imageworks (SPI) continues to bring audiences blockbuster movie effects as they introduce the villain Electro. To bring Electro to life and to create a variety of VFX shots ranging from destruction, water, explosions and more, Houdini played an integral role.

Electro’s look consists of three key elements. He has “e-skin” that depicts electric-like veins pulsing beneath the surface of his skin. For his special powers, Electro fires “e-blasts” which are lightning bolts which pre-charge within his clenched hands and, lastly, Imageworks also had to show how much impact a high-voltage character would have on his environment.

To create the look of Electro’s e-skin, Imageworks VFX Artist Dan La Chapelle used Houdini to build an intricate, branching, interconnected neural network that resided within Electro’s body. This allowed for an animation of pulsing bands of energy to flow along Electro’s synapses. 

The animation of these flowing synapses was accomplished using Houdini, which allowed Imageworks artists to create a lot of overlapping patterns, with different timing that could eventually be combined in different ways by the compositors who were putting the shots together.

Houdini was an essential tool when it came to the generation of Electro’s e-blasts, as seen in the film’s Times Square and Power Plant sequences. 

Imageworks VFX Artists Spencer Lueders and Cosku Turhan built a variety of layers used to generate a complex "nebulae" look in the bolts - essentially a system to generate branching arcs using a combination of Houdini’s VOP networks inside nested ‘for each’ loops which then spawned off into several other layers.

Aside from Electro’s e-skin and e-bolts, Imageworks was presented with the task of defining how his overall environment reacted to his destructive energy. Custom surface solvers and particle simulations were created to add additional elements such as the electrical netting that filled his environment, or Tesla arcs that would crawl over the surface of Electro’s skin along with objects that were close to him. 

In addition to the primary e-blast effect, Imageworks VFX Artists Patrick Witting and Dimitre Berberov developed what was termed the "pre-charge" effect, a kind of super charge of violent energy that would engulf Electro's hands before he fires a blast. This was later adapted into something that Imageworks termed "e-pickle" which was a static electricity version of the pre-charge. To create this effect, a customized geometry solver was made to achieve the concentric spiraling of electrical arcs that surrounded Electro's hands.

Houdini was integral for Imageworks FX TD Chris Messineo’s development of this effect. He converted Electro into a dense point cloud, which he then noised around and flung along a curved trajectory marked by Electro’s motion. Chris found that Houdini was ideal for this kind of motion analysis and interpolation, and also for carrying around the texture/look information of the character. In essence, the point cloud needed to look exactly like the textured/lit rendition of Electro when he wasn't devolved into his atomized, E-Ghost state. 

This meant that Imageworks artists had the freedom to do anything to Electro that they could do to an arbitrary point cloud, essentially allowing them to fragment him in all kinds of interesting ways and then re-form him in a similar manner.

Aside from all of the associated VFX work for Electro, Houdini was also used to handle a range of VFX for the film. Imageworks VFX Lead Charles-Felix Chabert led the Destruction team who created everything from the large-scale destruction sequences of Times Square and The Power Plant, to smaller set pieces like Electro flattening the Oscorp Office. 

Imageworks’ core tool for destruction was a custom implementation of DMM running through Houdini’s dynamics level, but they also used geometry level implementations of Bullet, PhysX and ODE in Houdini. Houdini was the perfect framework for this type of work as it enabled Imageworks to customize lots of specific auxiliary tools for improving and refining destruction techniques. Almost too many to mention, but anything from shared edge analysis, to post sim solvers for applying clean up and fixing errors were crucial.

Imageworks also performed copious amounts of fire, explosions, smoke, dust, debris, tear gas, shockwaves, mushroom clouds and mist throughout the movie. In most cases, variations of smoke and fire created with Pyro FX solvers were used to achieve the desired aesthetic. 

The open nature of Houdini's dynamics tools really allowed technical artists to create custom set ups to meet a number of unique challenges. Houdini's Open VDB tools offered great flexibility and optimization, particularly in building inputs to fluid simulations, and the powerful capability of VOP networks allowed us to have highly specific control over the behavior of simulations.

Due to the sheer amount of VFX in the movie, Imageworks utilized everything from off-the-shelf networks, to networks built entirely from scratch using micro-solvers, to combinations of both to get the job done right. Houdini's up-res technology, re-timing tools, and rest field options were critical in allowing them to achieve the required amount of detail in their simulation work in a manner that was efficient and flexible.

For water-based VFX, Houdini’s fluid solvers were used. This included a custom drip that used a SOP solver inside a FLIP set up to simulate tiny drops clinging to skin, and larger scale simulations like an exploding water tank, fire hose and hydrant spray. 

Imageworks also found Houdini to be a useful tool for the early stages of production such as preliminary shot composition. 

In The Amazing Spider-Man 2, Houdini was used to create many variations of the same element, which then allowed for quickly populating the environments with effects. In the Power Plant sequence for example, Imageworks generated numerous simulations of fire to be used with burning debris. Because Houdini is completely procedural, it meant that they could quickly swap in different debris as the source for the fire, providing a result with similar characteristics but also with realistic variation. 

This also meant that Imageworks artists could hand off a whole raft of pre-baked simulation elements to their shot layout and lighting artists while allowing them the freedom to move elements around or change their composition without having to continually run new simulations.

“Where Houdini helped with this was the ease with which we could build hugely varied libraries from one base simulation setup” says Joseph Pepper, FX Animation Supervisor at Sony Pictures Imageworks.

“Beyond that, I would say anything that gives us flexibility, efficiency and the ability to change things without manually regenerating all the steps involved is a huge help in any creative endeavor. For example, our ability to quickly turn around iterations on certain elements, such as electrical netting from Electro, or arc and spark FX, definitely led to more such elements being added to the movie. As we produced certain elements like these, the director and VFX supervisor started wanting to see them appearing in more places in the movie where they weren't originally requested. This helps keep the creative composition of all the FX in the movie an organic process, allowing for more adjustments on the fly depending on what works creatively and what doesn't.”

With Houdini, it was possible for Sony Pictures Imageworks to create a visually sophisticated Electro complete with electric skin, surging bolts, and corresponding environmental effects. At the same time, Houdini played a significant role in the film’s bread-and-butter VFX work such as destruction, smoke, fire, and water, and supported the artists as they brought this latest chapter in Spider-Man’s life to the big screen.