For the destruction of The Eiffel Tower, Digital Domain had to write the code so that procedurally when it detected no more connections for a piece of metal, it would know to drop.

It all culminates with the collapse of The Eiffel Tower. "We had to match it and make it look as believable as possible. And I think we have the most detailed model of the Eiffel Tower every built, so if you know anybody who wants it, we would love to rent it out. The most difficult thing about this sequence, in addition to The Eiffel Tower being eaten, was dealing with the falling pieces as its being disintegrated by the Nanomites. It was a case of rigid body dynamics, but the Nanomites would also eat around certain areas and leave island structures in the middle. We had to write the code so that procedurally when it detected no more connections for a piece of metal, it would know to drop. Then we got into the whole failure of the structure issue when The Eiffel Tower loses a leg. This includes vibration when a structure can't feel it all the way to collapsing and crashing into the Seine River. We looked at reference of buildings falling, but not steel structures. We contacting an engineering firm and figured out where the failure of The Tower would occur once the legs are gone."

Both Digital Domain and Prime Focus VFX (formerly Frantic Films VFX) shared work on the Nanomites. However, Digital Domain wanted to drive the look "because we didn't want to be chasing our tales, and it just so happened that we were able to solidify the look with our sequence and keep moving forward," adds Grill. "We each used our own proprietary softwares for the Nanomites: we used Storm and they used Krakatoa. And, surprisingly, we both achieved a complementary look and it was hard to tell the difference."

Digital Domain used its proprietary Storm software for designing and animating the Nanomites.

Prime Focus handled the climactic attempt to thwart the Nanomites from destroying Washington, D.C. and the White House. "I challenged the guys at Prime Focus to render aerial skies and ultimately landscapes to virtualize the Potomac and Washington, D.C.," says Shermis. What they did is fantastic. They came up with a methodology -- they basically designed their own software and rendering tools -- to create aerial skyscapes, which, as far as I'm concerned, are the best I've ever seen in an aerial chase like that."

Prime Focus, which started out contributing previs, wound up creating roughly 70 out of a total of 124 visual effects shots for the finale's aerial sequence. Says Chris Bond, senior visual effects supervisor and president of Prime Focus VFX, "This sequence was particularly challenging because we weren't relying on any aerial photography, which would be nearly impossible to shoot at these speeds, but instead created nearly everything digitally -- the plane, sky, clouds and the destructive Nanomites that eat away the plane."

In addition to developing a custom toolset to generate 3D cloud and sky environments, Prime Focus built a Nanomite animation pipeline and a hybrid matte painting, environment and 3D animation pipeline. The company also dedicated extensive R&D to improving its in-house scene collaboration system that allowed its LA and Vancouver offices to work seamlessly together.

"We created a system whereby no single shot lives as a whole, but rather as a collection of project, sequence or shot assets," adds Chris Harvey, visual effects supervisor for Prime Focus VFX in Vancouver. "Assets could range from models, shaders, animations, scripts, light rigs and anything in-between. These assets would then be assembled on the fly based on the specific requirements. This facilitated a number of important aspects to our pipeline - artists would always have the latest approved assets regardless of their global location, and we could make changes en masse and have them propagate through various levels of the show, shot, sequence and even across the entire project."