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How the ‘Interstellar’ VFX Team Built Wormholes, Black Holes and Alien Planets

How the 'Interstellar' VFX Team Built Wormholes, Black Holes and Alien Planets

When it came to wormholes and black holes, Christopher Nolan set out to make the most physically realistic sci-fi movie ever made with “Interstellar.” The VFX results are spectacular and Oscar-worthy, even compared to last season’s Oscar-winning “Gravity,” demonstrating how high the bar continues to be raised technically and creatively when it comes to space adventures.

In fact, the ground-breaking VFX work on the black hole by Double Negative is so brilliant that physicists will now have actual models to study for the first time, thanks to breakthrough rendering capabilities. 

Situated somewhere between “2001: A Space Odyssey” and “The Right Stuff,” Nolan’s movie is obviously a different gravitational force from Alfonso Cuaron’s blockbuster, and a wonderful companion piece to “Inception.” “Kip Thorne provided the physics,” recalls Oscar-winning VFX supervisor and Double Negative co-founder Paul Franklin (“Inception”). “Wormholes connect two points in space-time like a giant spherical lens in space and theoretically allow time travel. Kip explained that wormholes are theoretically permissible under certain circumstances but are very unstable.”

A black hole, by contrast, is a region of space-time from which gravity prevents anything from escaping, including light. It is completely black with no surface detail. “Kip worked with the R&D team at Double Negative, which developed a new renderer called The Worm Renderer, which calculated the relativistically warped space around the black hole [called Gargantua] and ray traced all the light paths around it [as well as around and through the wormhole]. When we saw the test versions of the renderers, I realized that we didn’t have to embellish it.”

Dneg set up the shots in a fairly traditional fashion, using previs and a proxy object standing in as the wormhole. There was a lot of trial and error because shots in the renderer didn’t behave the way you would intuitively expect. As you approach the wormhole, the object didn’t necessarily maintain its size and weight. And the closer you got to the warped space around the wormhole, you would actually shrink in size relative to the camera. Also, as you got closer, the distortions behaved very unexpectedly. They constantly ran the renderers to see what came out the other end.

For the journey inside the black hole, they looked at early slit scan photography predating The Stargate in “2001.” They also read about cosmology and objects leaving a trace of matter in space as they travel in time. The most fantastical part of “Interstellar,” however, occurs inside the black hole, where Matthew McConaughey encounters the Tesseract: an artificial construct that allows him to perceive time as a physical dimension. Inspired by abstract modern art, and utilizing a familiar environment, the Tesseract is comprised of interlocking cubes where you can track movement through a series of time slides. Franklin helped design the Tesseract with production designer Nathan Crowley, which became a physical set with CG extension.

Speaking of CG, there is no green screen in “Interstellar.” Instead they were inspired by the old school approach of “The Right Stuff.” They used miniatures of the three spacecraft (The Endurance, The Ranger, and The Lander) made by New Deal Studios in LA, and shot them under real lighting conditions with realistic exposure ratios and got the cameras to behave naturally around them. In the end, they wound up with less than 10% of the spacecraft shot digitally and used 150 miniature shots. 

“We realized that we could do a modern version of front projection using Barco projectors,” Franklin adds. “We built large projection screens around space craft windows. One was 300-foot long x 80-foot high. And we threw big images of the wormhole and black hole and star fields and shot in camera. This gave us a great look visually and allowed the actors to put themselves in that space. We were often creating content moments before it would appear on screen and the cameras would roll. We were developing the images of the wormhole and black hole as we went along and improving the software.”

Naturally they wanted space to look as realistic as possible. Dneg got a hold of a NASA database of stars with correct position, magnitude, and color temperature, and then built another new renderer called the Star Field for determining the size of the points.

As for the two alien planets — the water planet and the ice planet — the crew shot in Iceland for both. But for the water planet, Dneg created a series of 4,000-foot animated waves using basic deformers along with detailed simulation work on top. “Basic animatics would come out quickly but then it took months to get final renders of the simulation work at IMAX resolution,” Franklin adds.

For the ice planet, Dneg created a surface comprised of marble sheets of ice from a combination of CG and matte paintings. “Everything is grounded in the gritty, hand-held photography of Hoyte van Hoytema [who modified the IMAX camera]. You get a level of tactile reality that puts us right there,” Franklin concludes.

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