Since working on the original “Twister” in 1996, visual effects supervisor Ben Snow has earned four Oscar nominations for his contributions to fantasy projects, including “Iron Man” and “Star Wars: Episode 2 – Attack of the Clones.” “. But when he oversaw the visual effects for this summer's hit disaster movie “Twisters” (starring Daisy Edgar-Jones and Glen Powell), that particular F-word never entered the conversation.
Following director Lee Isaac Chung's lead, Snow and his team at Industrial Light & Magic abandoned exaggerated fantasy to make the Oklahoma tornadoes look as real as possible. “We found it was best not to put too much pressure on the environment,” Snow says. “We talked about the possibility of doing a surreal, almost post-apocalyptic yellow look, but it had this artificiality that we didn't like, so we leaned towards real photography as a starting point.”
Speaking from his vacation in Kyoto, Japan, Snow spoke to The Envelope about teaming up with storm chasers and data controllers to create the appearance of havoc-wreaking weather.
These are heartbreaking times when it comes to extreme weather. How did you use computers to generate such realistic tornadoes?
We sent storm chasers who actually ran into the weather and filmed very high resolution moving images. That gave us the ability to study tornadoes in much more detail than ever before. We also had a photographer, Giles Hancock, who took high resolution photographs. [photo] sets of storm clouds. If we were filming on a somewhat sunny day, we would use Giles' cloudscapes to populate the backgrounds, build [computer-generated] clouds above and then the tornado above.
How did you coordinate the division of labor with the special effects team?
I sat down with special effects director Scott Fisher and we decided that he would give us the first 60 feet of weather. [with practical effects]. They would blow some grass near the car or give us some dust so the crew and actors would have something to react to. The rest of the scene was visual effects. All the trees along the road, the utility poles, we created them on the computer and whipped them with the wind. The objective was to resolve the battle.
Were you able to essentially sculpt each of the film's six tornadoes to your liking?
Lee had a desire to make each tornado individual so that each one would be like a character. If you said to me, “We want to change the tornado to something more like a wedge shape,” the artists understood how to make that change. As a first step, the animators created a set of controls so they could basically animate large sculptural tornado shapes around the landscape. We would then work out the choreography, and then the particle team would take that information and use very elaborate simulation engines to get the basic trajectory of the tornado and address its effect on the environment. We used every trick in the book.
Before and after photos show how the visual effects team turned wireframes into stunning CGI shots of realistic tornadoes.
(Lucasfilm)
“Twisters” begins with heroine Kate (Daisy Edgar-Jones) traumatized by a ferocious EF-5 tornado blowing at more than 200 miles per hour. How did you approach that from a story standpoint?
Tornado 1 is like the shark from “Jaws.” You see it lurking in the cloud, you catch a glimpse of it, but we tried to make it mysterious and show this big visceral impact when it hit.
Tornado 4 wreaks havoc on a rodeo, sending a horse trailer flying through the air…real or CG?
The big trailer is really there. The part where it falls into the pool is the computer graphics. Then it becomes real for a moment, then goes back to computer graphics. If the audience sees enough of the real thing, that gives us the chance to mix things up.
In the film's grand finale, Tornado 6 destroys a factory, catches fire and destroys a movie theater. How did you orchestrate all that intensity?
This tornado had so much going on that when we used our simulation engines, we couldn't keep it all in memory. We had to break that. [sequence] on small tornado bricks where the tool would simulate one fragment and then say to the next: “This is what happened.” All adjacent components worked continuously making sure the particles they were simulating went to the right place.
CGI technology has, of course, You've made great strides since working on “Twister” 18 years ago.
A tornado in “Twisters” probably required as much computing power as we used to create the entire first “Twister.” It's crazy. For this one, we had an amazing simulation toolset called ILM Pyro where you can take parameters from a real storm and insert them. The system is doing billions of calculations, almost like the ones scientists use to map real climate, but we were doing it to plot simulations to look at airflow vectors and that kind of thing.
You reversed these weather sequences with six tornado tones. grey that enhance the evil vibe of each storm. How did you approach the color palette?
With twin tornadoes, there is a very distinctive red dirt appearance that we integrate into the debris field at the base of the tornado. With the EF-5, it's on grass; Obviously we all know what grass is like, so we had a little more license to say, “Okay. What's the coolest, scariest looking tornado we can find?
