Far from being killed off by digital, practical special effects are routinely used to heighten the effectiveness of scenes and emotional beats in a way impossible in a computer.

In one of the standout action scenes in Mission: Impossible - Fallout, Ethan Hunt endures a high -speed crash as the helicopter he is piloting is forced to smash into a snow covered mountain.

Mission: Impossible - Fallout

Mission: Impossible - Fallout

Source: Paramount Pictures & Skydance

It’s a classic example of how practical special effects (SFX) can deliver a greater sense of reality and danger to the audience, even as visual effects (VFX) techniques advance toward the photoreal.

Star and producer Tom Cruise has made his involvement in stunts like these a signature of the Mission Impossible series and was reportedly unhappy with the way a CGI-created car crash, with his character supposedly inside, had looked in Mission: Impossible 5.

For Mission: Impossible 6, rather than animate a CG helicopter and shoot the actor in a mocked-up interior, a full-size helicopter from Airbus was rebuilt with new metal bodywork and roll cage and suspended by winches on a gimbal. Various parts of the machine were designed to break away on impact, cameras were discreetly positioned inside, Cruise climbed aboard and the craft sent spinning into the ground.

“If this were a full CG shot I don’t think you could accurately work out all the elements that would make it believable,” says Neil Corbould, the Special Effects Supervisor behind the sequence. “Doing it this way means the lighting is correct as the helicopter spins in daylight, the snow comes in with the right force, it rolls at the right speed, there’s weight and mass to the shot. Plus, you can really believe Tom’s performance.

He adds, “An actor will always react differently if they’ve got a blue screen or a projection in front of them as opposed to feeling and seeing something real.”

For directors like MI:6’s Christopher McQuarrie, Steven Spielberg, Christopher Nolan and Ridley Scott, the analogue look of recording as much as possible in-camera means practical sfx remain a staple of the most high budget blockbuster.

Actors performance
Go back in time and everything was physical. Think of Buster Keaton with entire buildings falling down around him. Instead of wind machines, actors had to interact with real snow and rain blown into their faces. Their squinting is for real.

“The difference with CGI is that actors have to imagine being cold or having water run down their face,” says Phil Anderson, designer, pyrotechnician, and founder of Especial Effects Co. “When you have a real fire in front of you, you feel like it’s almost a barrier you can’t cross but the lack of a fire in a blue screen environment inevitably affects the actor’s response.

“Same with a big explosion – if it’s real you will feel that concussion wave strike you. The delay in feeling the wave from the moment of impact will feel real on screen – because it is.”

Of course, explosions are set off in a controlled manner at safe distances and supplemented with material like safe dusts timed to blow at the same time.

Practical special effects artists are tasked with creating everything from atmospheric effects like fog, rain, snowstorms and pyrotechnics to designing and operating mechanical hydraulics, robotics or pneumatics. Disciplines also include prosthetics, animatronics and puppets, special costumes, model making, and liquids.

A gas explosion for a CGI element later to be added into a feature film

A gas explosion for a CGI element later to be added into a feature film

“Fire is a lot more complex than it seems,” says Anderson. “It produces light photons that bounce off every surface and then re-emits photons to other parts of the set. Even if you could simulate that complexity in a computer it will take a lot of time and processing power to render it.”

The last season of Game of Thrones deployed a real flamethrower to produce a 50-60ft flame emerging from what would be the dragon’s mouth. “It burnt into the ground and you could see the heat haze with much more verisimilitude than if done with CGI. It’s subtle, but it makes the difference,” says Anderson.

Even on a virtual set the use of a mechanical rig may be necessary to jerk the performers around in unnatural movements which they may not be able to mimic alone.

“Actors and directors are not great fans of working in a sterile green screen environment if it can be avoided,” says Mike Kelt, co-founder and CEO at Artem. “They are there, as are we all, to tell a story, and if the best way of doing that is for real then the industry will continue to thrive.”

CG and practical together
There was a time, though, when VFX threatened to consign special effects to history. For many the watermark was George Lucas’ return to the Star Wars universe with the series prequels beginning in 1999.

“For better or worse the aesthetic approach established by Lucas defined the look of modern cinema,” says Paul Franklin.

Neil Corbould traces the threat further back to the dawn of CGI in the mid-eighties. “Lots of VFX supervisors were saying SFX was a thing of the past and we should all be looking for different jobs. But in 2018 the technique is probably stronger than it’s ever been.”

It’s a familiar tale. “When I first got into special effects I was told I’d be replaced within five years by a computer,” says Alex Gunn, special effects supervisor, Arcadia SFX. “Instead, digital technologies have enabled many of us in physical to achieve things we couldn’t have done before.”

For example, Gunn says he used to suspend actors on wires “but they’d wobble and not have a smooth powered look to them. Now, we can build wonderful hydraulic contraptions or hang wires on massive pole arms, paint the whole thing green and have it digitally removed in post.”

The truth is that visual and practical effects go hand in hand. It was too dangerous to have real spinning rotors on the crashing helicopter in MI:6 so these were added digitally.

Artem uses computer graphics to design and visualise what it is about to build. It employs scanning, 3D printers, CNC machines and robots to do a lot of the prep work for models and other contraptions which are then finished and operated by hand.

“In some ways the advance of CGI has grown the physical industry as so much more is now possible in film or TV,” says Kelt. “CG allows more to be achieved story wise, but SFX is required to support it or tie it into a scene.”

SFX supervisors are typically hired in the early stages of production to advise on the effect and look a director wants to achieve.

“I’m the first to pipe up and say it’s best to go CGI,” says Corbould. “When director Alfonso Cuaron wanted to recreate the zero G of Gravity almost entirely on a revolving 60ft set and wire rig, I advised that, given the schedule and what sound-stages were available, the majority should be CG.”

Corbould did build a rig to support Sandra Bullock using 12 rather than the usual two wires so that she could freely move her arms, hips and legs around a green-screen space for hours at a time. It helped him win his second Oscar (after Gladiator).

“The most successful projects are where the physical and digital effects are discussed openly to find what will get the best action on screen, rather than inflate either’s profit margin,” says Kelt. “Often it is by working together that great things are achieved.”

The budget equation
Arguably TV drama is the last bastion of true physical effects mainly because the pressures of the tighter budget and time constraints mean that physical is often cheaper and always quicker than CG.

Most shows don’t have the budgets of a Bond film which has the luxury of three months to plan and film a single large explosion.

“If a TV production wanted an explosion 20ft high by 40ft wide, I can produce that effect and add debris, and design it so we know which way the bits are going to fly,” explains Anderson. “They make multiple takes and it will only set them back £70 per explosive charge compared to animating the same in CG where it might cost £200 per hour.”

Gunn says: “It has to work on the day. There is no ‘fix it in post’. You have to find a way of hiding all the wires and mechanical rigs. When we shoot action sequences for soaps we slot into the regular shooting schedule. What we shoot in June is seen by the viewer in September. There is no time to tweak it massively unlike a high-end drama where there’s months devoted to post production.”

ITV soap opera Emmerdale has made dramatic Hollywood style climaxes a signature of its recent seasons with Arcadia invariably behind them.

Source: YouTube / Emmerdale

For the multi-car crash aired in 2016 multiple village favourites were seriously injured as an impressive stunt wrecked 14 vehicles. Characters Aaron Dingle and Robert Sugden found themselves veering off a steep bank into the waters of a quarry and trapped in their car as it sank. The entire sequence was played out underwater for real.

Explains Gunn: “You can’t simply fill a car with CG water around it. You want to see the light levels changing as the car sinks deeper and bubbles rising, both effects which would pose immense problems in post.”

Acadia took the shell of a car and rebuilt it so it would withstand 1.5 to 3 tonnes of water pressure. They added a roll cage and worked out how get the actors in, how to get them out and how they’d control the air they breathe and the carbon dioxide they breathed out. After testing, ITV allotted five days to shoot the scene.

“We did in four,” says Gunn. “The only difference if we were shooting this for a feature film would be that we’d film from more angles and move the rig around a bit more. Soap’s don’t have a budget for a huge stunt attendance. When we crashed a helicopter into the [Emmerdale] village hall it was the cast not the stunt performers who were watching on.”

For director Matthew Heineman’s forthcoming drama A Private War depicting the death of journalist Marie Colvin in Homs, Syria, Arcadia re-created the fatal explosion on location in Jordan.

“We rigged a large explosion of fuel some distance from the cast and synchronised that with an air canon firing fake debris and dust around the actors,” explains Gunn. “The aim was to convey the force of the shell hitting the ground which buries our main character in rubble. The most incredible testimony to what we shot was from Paul Conroy [the photographer who suffered leg injuries in the attack in which Colvin died] who was on set when we filmed. He said that that was exactly how it was.”

“When I first got into special effects I was told I’d be replaced within five years by a computer”  Alex Gunn, Arcadia SFX

Models and miniatures
Filmmakers have long used miniatures paired with forced-perspective photography to create realistic large-scale actions that are expensive, if not impossible, to do for real.

While miniature model making for TV commercials has been killed off (by CG packaging) this aspect of the craft is still alive and well.

Director Christopher Nolan often prefers models over CGI to achieve what he believes is a more organic feel. Much of the Gotham cityscape for Batman Begins was built in miniature by Robbie Scott at Cutting Edge.

“It was impossible at that time for a computer to have coped with all the complexity,” says Paul Franklin, co-founder of DNeg and regular vfx supervisor for Nolan’s productions. “It could be done digitally now but Chris wanted the shot to fit in with the grounded world of the rest of the film. Use of models gave a sense of tangible reality and fitted the language of the film.”

When it came to Interstellar, Nolan had life-size models of spacecraft built to retain the feeling of a NASA archive film from the Apollo era. “The spacecraft weren’t perfect, there were lots of join marks and you could feel the weathering from being filmed on location in Iceland but this was perfect. Chris wanted the audience to feel like they could reach into the shot and grab hold of it,” says Franklin.

For Dunkirk, the crew were able to find real WW2 era Spitfires but since there were no flying examples left of a German Stuka and Heinkel twin engine bombers the only solution was to build (by sfx artist Scott Fisher) third scale models.

“All the aerial battles were meticulously planned in pre-viz taking into account all the manoeuvres one of these real planes could do,” says Franklin. “The models had to behave like real aircraft and so long as they were shot carefully they didn’t give away their true scale.”

Quite often it’s cheaper to hire a model maker than 500 vfx artists each working on 10 frames of film. “One advantage of miniatures is that you can move the camera around them in 360 degrees, or go back and reshoot from a different angle, whereas with CG you’ve got to completely re-render everything,” says Gunn.

Of course, you can spend months building a model spacecraft and then blow it up and it’s gone forever – unlike the reusable CG assets in a computer.

Some models such as animal animatronics are unlikely to be built as much now as CGI has become so expert in rendering and animating creatures.

“But again, depending on what the shots are, an animatronic can make it cheaper by achieving the majority in camera and adding extra animation in post,” says Kelt. “What do you want something to look and act like? Maybe the creative decision is that the quirky nature of a puppet is best achieved with, in fact, a puppet - hand operated and given life.”

“In some ways the advance of CGI has grown the physical industry as so much more is now possible in film or TV.” Mike Kelt, Artem

Replicating random
Visual and special effects legend Douglas Trumbull is not alone in preferring the random accidents of practical fx over the perfect gloss of digital.

“I like to be open to the surprises you get which you could never write an algorithm or computer code for,” he says. “That to me is the allure of shooting organically… it keeps things fresh.”

Franklin calls it the “unexpected nature of reality”. He says, “If you shatter a window in a computer the effects artist will make it blow out in spectacular way but it’s contrived. The reality is that the glass falls out of the frame and we know when we see this on screen if it’s believable or not. There’s a lesson for cg artists in dialling down the effect.”

One area where CG trumps physical is water modelling. It’s notoriously hard to scale down an ocean, to re-create a tsunami or to replicate water surface tension using physical techniques. However, CG liquids can be paired with practical work.

For instance, the opening scenes of Les Misérables of a ship being towed into dock were all CG except for the crashing waves hitting the harbour that were shot at Artem and composited into the shots. “They wanted to do that in order to capture the unexpected nature of water splashing against the harbour wall,” explains Kelt. “We built a big tank and filmed water thrown against green screens. They could take that and paste it into their composite, whereas trying to make that up in a computer would be tricky because of the random element.”