How do you make a robotic arm for a TV show, anyway?

Legacy Effects shares its process for ‘Tales From the Loop’.

In pre-production on the Amazon Prime Video series Tales From the Loop, the adaptation of the art book by Simon Stålenhag, Legacy Effects co-owner Alan Scott was asked by show creator Nathaniel Halpern about a particular effect that he was looking to achieve; the bionic arm for the character George Willard (Paul Schneider).

“Nathaniel wanted to do these shots where George, who is shirtless, gets up and walks over to the robotic arm that’s on a table, puts it on, and it comes to life, all in one shot,” recounts Scott. “My first reaction was, ‘Well, you’re going to do that in CG, right?’ And Nathaniel was like, ‘No, we wanted to see what you could do with it. We want to get that in-camera as much as we can.’ For us, that was awesome to hear.”

Paul Schneider with the Legacy Effects prosthetic.

Scott’s immediate thought was finding a way for the actor, Schneider, to be a key part of the ‘missing arm’ gag, in that he could control the movement of the robotic arm itself and move around the room without any puppeteers in tow. But this led to the challenge of working out how to attach the robotic arm to the shirtless actor, and have it supported and be articulated in one continuous shot. “Effects like this can look great from one camera angle and then from a slightly different angle, they look terrible,” attests Scott.

So, Legacy Effects got to work on a proof-of-concept design and then an actual working test. “We just grabbed a bunch of things and some weird robotic parts that we had laying around,” recounts Scott, noting this was a test video to show how the prosthetic arm could attach to the actor, how the actor could puppeteer it, and how it could be done on set with and without post-production on the arm.

Photo: Jan Thijs 2019.

“We put a black sleeve on our stand-in, and shot it on black. In the video we crushed the contrast down until you couldn’t see his real arm, mimicking what VFX would do much more expertly later as part of this proof-of-concept, and it worked.”

With this successful test, the show’s makers were convinced a practical FX approach was possible for some shots. An arm prosthetic was sculpted, painted and built to be worn during filming. However, Scott also knew one of the major requirements was for the scene to have Willard pick up the arm from a table, attach it and for the shot to continue. The solution: electromagnets. “We made it so that as the performer moved the arm up to the connector, those magnets would engage and it would click in and come to life.”

Alan Scott puppeteers the arm. Photo: Jan Thijs 2019.

Schneider was given control of all the wrist and elbow movements in the fake arm; these movements were effectively slaved to his shoulder while his real arm, holding a rod that connected his hand to the hand of the prosthetic, effectively placing his arm behind the fake one. Sometimes the robotic arm was puppeteered by a Legacy Effects artist on set, too, depending on the set-up.

For the more intricate finger movement, Legacy Effects added robotic servo motors to the mix, operated by remote control. “New robotic servos that have come out in the last two years have really transformed a lot of what we’re able to do with animatronics,” says Scott. “And these servos are virtually silent. So we could have 12 of them working and moving, right there attached to the actor, and it didn’t affect dialogue once. They have amazing dampening and smoothness functions now built into them. They’re basically little computers on each servo.”

Photo: Jan Thijs 2019

Since there were a variety of different angles and types of shots required with the bionic hand, Legacy Effects’ work was also augmented via digital visual effects from Rodeo FX either in terms of the removal of prosthetics or rods, or to provide for a completely CG arm and hand. For example, in certain scenes Schneider wore a green glove or sleeve. The VFX team would then remove the green and replace that with a CG arm or hand.

Legacy Effects also made a wearable glove with a robotic arm look printed on it, with extra dimensional pieces, that was intended for when the character was further away from camera. “It wouldn’t work for any close-ups, but it was good for other shots,” notes Scott. “If they went with all green, then they would have had to replace it for every shot. So we made these gloves that could work in medium to wide shots and with minimal touch-up or little CG. When the arm required very dextrous movement, Paul’s gloved hand was replaced completely with VFX.”

Rodeo FX crafted these CG close-up hand/arm shots, always using what had been shot on set – either the animatronic or glove – as reference. “Rodeo took a lot of our performance cues,” says Scott. For the technology that’s in the show, it really fit because it’s old technology that’s been around for a long time. There’s a charm to the puppet aspect of it and Rodeo replicated that, meaning there wasn’t a performance difference between what they were doing in VFX and what we were doing in puppeteering.”

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