How Marvel movies are actually created years before production begins

• We talked to Hollywood's busiest visualization studio, The Third Floor, to find out why visualization is the secret MVP of Marvel movies.
• The Third Floor is one of the world's top visualization studios and has worked on 19 of the 23 installments in Marvel's "Infinity Saga," from 2010's "Iron Man 2" to 2019's "Spider-Man: Far From Home."
• While previs used to be used for just one or two tricky action scenes, Marvel has embraced the approach of visualizing entire movies, including quieter beats and dialogue scenes.
• From previs and stuntvis to techvis and postvis, The Third Floor's work on Marvel movies runs through the entire production process.

Following is a full transcript of the video.

Narrator: This shot is a rough version of the final battle in "Avengers: Endgame." And it looks pretty similar to what you saw in theaters. But the process of putting this rough shot together began three years before the movie came out -- well before the actors went on set and before a single frame was captured on camera.

These rough shots are called previs, short for previsualization. Essentially, this tool allows filmmakers to digitally map out how they want any given scene to look. Directors can then use the previs as a guide for how to film scenes, sometimes frame for frame, once everyone's on set.

Previs has been around for a long time. But in earlier movies, it was used in a much more limited way.

Chris Edwards: They were used for just small pockets of that movie. For the one big visual effect shot, for the big finale sequence.

Narrator: But now, instead of just using previs in small doses, companies like The Third Floor have developed it into a tool for designing entire movies. And no studio's embraced that approach more than Marvel, which has enlisted the help of The Third Floor for 19 of the 23 films in its Infinity Saga.

For 2014's "Captain America: The Winter Soldier," Marvel had gotten to the point of previsualizing two-thirds of a movie. Today, the studio is known to use visualization to map out every single scene.

Not just action scenes, either; for "Endgame," The Third Floor's work touched everything from the comedic scene with Hulk in the diner to emotional moments like the one between Hawkeye and Black Widow on Vormir, leaving nothing up to chance in one of the most expensive movies ever made.

The first visualizations of a Marvel film will often begin before the script's fully finished.

Chris: And that actually is the best place for a professional visualization team, is to be able to make bridges and try out some experiments between departments that have a crazy idea that may or may not work. You want to be able to throw things at walls and see if they stick.

Narrator: Occasionally, rough previs might be underway even before the cinematographer or director has signed on to the project, a practice that can be controversial in Hollywood. Director Lucrecia Martel said she turned down the offer to direct the upcoming "Black Widow" movie after Marvel told her not to worry about the action sequences.

It is true that Marvel encourages their team of previs artists to play an active role in story development.

Jeff Ford, the editor for "Endgame," said that The Third Floor's visualization supervisor Gerardo Ramirez, who'd worked on nine prior Marvel films, was like an additional director, writer, and editor on the project. That's because previs artists are involved in just about everything from the start, helping to map out story beats and shots and consulting on everything from blocking, staging, lighting, how heroes will use their power in big fights, and even the timing and tone of any given scene.

To understand just how crucial previs is to Marvel's process, let's go back to that final battle from "Endgame," specifically the "Avengers assemble" moment, when all the heroes return one by one through portals.

The Third Floor presented Marvel with two previs'd takes on that arrival moment. One was slower and more emotional, while the other was higher energy and had the heroes arriving mid-charge. Ultimately, Marvel went with a blend of the two versions.

A lot of this is done to save money.

Today's previs tools allow filmmakers to do virtual location scouting and test out advanced camera work.

Take, for example, the Sony/Marvel movie "The Amazing Spider-Man," which was shot in 3D. The filmmakers wanted to have some cool first-person shots of Spider-Man swinging through New York, but they didn't want to make audiences nauseous. So they used previs from the visualization studio Proof to determine how much and what type of movement people would be able to handle.

All of this is then extracted into a blueprint for production called techvis, which provides filmmakers with all the data and diagrams they'll need to actually recreate each shot in real life.

Essentially, this is where all the detailed math happens. Remember this scene from "Thor: Ragnarok," where Heimdall leads the Asgardians across the bridge?

The Third Floor did the techvis for that crane shot to work out the camera height and lenses they'd need along with the distance from which they'd film the characters.

For "Endgame," they produced over 100 different technical mock-ups containing information like this, all of it accurate to the real locations and equipment they'd be using.

Getting all the numbers down pat is especially important for a movie like "Ant-Man," where characters dramatically fluctuate in size from one moment to the next, or "Doctor Strange," where the folding-city imagery required a lot of dimensional mathematics.

And techvis is useful for quieter beats, too. Marvel used it to define the camera parameters for this weighty scene between Hawkeye and Black Widow in "Endgame" to make sure they'd hit the right tone and visual impact. Filmmakers can even plug the data from techvis into a motion-control-camera system, which lets you program precise, repeatable camera movements.

Chris: They're also well versed in programming robotic dollies, robotic cranes that move the camera around.

Narrator: Setting up such a tightly controlled shooting environment can speed up production a lot. And when you're on location for a Marvel movie, every minute counts.

The visualization process doesn't end with shooting, though.

The Third Floor's work on a Marvel film can run all the way up to the end of postproduction because of the process called postvis. This involves taking a live-action photography they've shot and combining it with the previs elements.

Take this moment in "Endgame," where Strange, Spider-Man, and Star-Lord join the final battle. The Third Floor started with completely digital previs and techvis for the shot, which Marvel then used to film the actors on a green screen.

Next, The Third Floor reintroduced some key previs elements, like the background and the outline of the portal. For "Endgame," The Third Floor's artists made 7,300 previs shots. Over 7,000 of those ultimately became postvis shots.

The postvis shots serve as placeholders in early cuts of the film, allowing Marvel to quickly preview it before commissioning the finishing effects. Marvel will often screen these versions of the film, filled with postvis, in front of test audiences to get an idea of how the film might be received. Plus, the postvis shots provide a template to the VFX artists who take on the movie's final effects work.

Using visualization from beginning to end can save Marvel millions on expensive effects and shoots. And, ultimately, having all the technical stuff squared away will ideally free up the director to focus on getting the best performances from their actors on set.

Chris: They can be warned about things that are up and coming that might impact their craft, so that they're not surprised about it when they walk onto the set.

Narrator: But doesn't having all of these shots pre-rendered diminish the role of directors on Marvel movies? Not necessarily. Another advantage of in-depth visualization is that Marvel isn't limited to hiring big action directors. The studio's become known for their unconventional director choices, often pulling talent from the indie or TV circuit.

Chris: And that's where they can really benefit also from the previs process, as they can trust a team like ours to work with the stunt coordinator, so that all they have to do is be like an avid viewer of their own film as it's coming together and to be making comments, like they do with everything else.

Narrator: Some directors might chafe at Marvel's wide-ranging use of previs. Others may welcome the fact that Marvel has a dedicated team of previs artists and VFX specialists who know how to plan out action sequences.

Marvel's extensive use of visualization has helped the franchise maintain a coherent vision all the way through "Endgame."

Given Marvel's box-office dominance, other studios may follow their model of embracing visualization, even for smaller productions. The Third Floor has worked on a number of nonaction films in recent years, from art flicks like 2016's "Nocturnal Animals" to political biopics like 2018's "Vice."

Chris: Now that the digital world is merging in with the physical world, that is going to be the future of a lot larger swaths of content creation than just these very ambitious productions.