In 2013, our beautiful polar bears returned to the screen in a series of wintry adverts featuring the Coca-Cola slogan ‘Open Happiness’. Two decades before that, they appeared in 1993’s animated ‘Northern Lights’ TV spot. They’ve gone from watching the aurora borealis with an ice-cold Coke, to making snow angels and befriending puffins.

The famous 1993 advert was created by Ken Stewart, who was inspired by his Labrador retriever puppy.

It took a lot of work to bring the furry, thirsty characters to life. Stewart enlisted the help of Los Angeles-based Rhythm & Hues to animate the ad using what was considered at the time to be state-of-the-art computer graphics. Using storyboards by illustrator Eugene Yelchin, Stewart and his crew created pencil sketches of the bears. Next, the team studied films and photos of polar bears to understand how they move their heads, bodies and limbs. A sculptor created the bears’ heads in clay to define their look.

There have been lots of Coca-Cola polar bear adverts since the 1993 one. For the 1994 Olympic Games, the bears slid down a luge and soared off a ski jump. Another year, cubs were seen decorating a Christmas tree. And another, a family of polar bears built snow bears in their Arctic Home.

We caught up with Todd Shifflett, a visual effects supervisor at Rhythm & Hues who was assigned to “Northern Lights” as a digital artist.

The world of computer graphics was much different back in 1993. Help us understand the technical challenges you faced in bringing the polar bears to life on screen.

Our most powerful computers could barely render all of the polygons, so we used lots of little technical tricks to pull it off and make the bears look furry without being able to actually render fur. If you look at the evolution of the bears over the years, you get an idea of how much technology has improved.

Any special memories stand out from the project?

Oh, yes. This was, of course, well before the days of being able to back up work on the cloud. We had to back up on reel-to-reel tapes in a machine room, which was a labor-intensive process that required very long hours. None of us got much sleep during that project. As the new guy, I was working the night shift one night — we had more people than computers — when I accidentally typed a command to remove the entire project from the disc! Panic quickly set in, because I thought I’d wiped out everything. I went room to room and finally fessed up. Luckily, I found someone who helped me restore from backup, and the project lived on.

What was the overall reaction to the first polar bear ad?

The commercial definitely put us on the map. Once the first one was released, it became so popular that Coke decided to produce more of them. I was involved in at least three more commercials, including one of the polar bear family pushing a Christmas tree down the hill and another for the 1994 Olympics. Technology was changing quickly and we needed to adjust for that, but we also wanted to maintain the stylistic look of the original incarnation of the bears. They eventually became fluffier, and newer tools enabled us to animate more than one bear at a time. It was an exciting time, and it’s nice to know people still look back on it as a document in computer graphics history.

Watch the bears do their thing in this 2013 short film produced by Ridley Scott.