Before Jordan Mechner could animate a single step of Prince of Persia, he had to film his brother. David Mechner, dressed in white, ran, jumped and climbed in front of a VHS camcorder; Jordan froze the tape one frame at a time, photographed the television screen with a 35mm camera, painted the prints into silhouettes and fed them into an Apple II through a digitiser. “I had to trace pixel by pixel,” he told Wireframe, “and it was very much a homemade process.” That is rotoscoping: drawing animation over filmed movement, so that a character moves with the weight and timing of a real person. In games it belongs to a short list of titles and a shorter list of people — Mechner’s Karateka and Prince of Persia, and Delphine Software’s Another World and Flashback — and every one of them was praised for movement nobody else’s sprites had.
Fast facts
- What it is: tracing over film or photographs of a real person, frame by frame, to make animation.
- Where it came from: the cartoonist Max Fleischer, who filed a patent for the method in December 1915; Disney’s animators used it for Snow White and the Seven Dwarfs (1937).
- What it bought: movement with weight. Reviewers reached for “fluid”, “lifelike” and “silky-smooth” for every game on this page.
- What it cost: time and frames. Mechner worked from a few minutes of Super 8 film and a stack of photographs; Delphine’s artists traced about 1,500 frames for Flashback.
- Not the same as digitisation: a rotoscoped sprite is drawn by an artist over the reference. A digitised sprite is the video picture itself, cleaned up. See the table below.
From cartoons to computers
Fleischer’s patent, filed on 6 December 1915 and granted in 1917, describes filming a live performer and projecting the film one picture at a time onto a surface where an artist could “trace the lines of each picture”. Wireframe notes that he used it for the silent series Out of the Inkwell, whose Koko the Clown was posed by Fleischer’s younger brother, Dave. Mechner had grown up on Disney animation. “I appreciated good animation — Disney animation,” he said, and he only later found out that “Disney animators had used the technique as well”.
The European computer press had the idea ready to explain. Amiga Format’s 1992 guide to digitisers defined it in one sentence: “drawing an animation over live action, so that it looks like a cartoon but moves more realistically”. It named the two places its readers would know it from, the animated film of The Lord of the Rings and Prince of Persia, “where the game’s designer took pictures of his brother jumping around the flat”.
Karateka (1984)
Karateka was Mechner’s first published game and his first use of rotoscoping, written on the Apple II. “I used a Super 8 camera to film my karate teacher doing the punches and kicks that would be needed for the game,” he told Wireframe, “and I filmed my dad running and climbing onto the hood of a car to simulate climbing up a cliff.” Film was the constraint. “With Super 8, you get just a couple of minutes on the roll, so you’re kind of in a panic because if you wasted 20 seconds of film, you couldn’t just rewind and do another take.”
Brøderbund published the game in 1984, and it was on Computer Gaming World‘s readers’ chart by January 1985. Its advertising sold the method, with a different account of the footage: “The making of Karateka” described Mechner as “a karate enthusiast and a stickler for realism” who “used film clips of the first karate masters as a guide for the moves used in the game”. The advert listed Apple II, Commodore 64 and Atari versions. Enter’s review in May 1985 praised its “superb animation”, and passed on Brøderbund’s claim that “the screams were made by a black belt master, digitized and then transferred to disk”.
Prince of Persia (1989)
For Prince of Persia Mechner swapped the Super 8 camera for VHS, which let him play a take back at once and record it again if it was wrong. The rest of the process, in his words: “I would then put the tape into a VHS player that had a clean freeze-frame and put a 35-millimetre film camera on a tripod in front of the TV screen. The idea was to do a frame advance, take a picture, do another frame advance, take another picture and so on, using every third frame.” He painted each print with a black marker and white paint, taped eight to twelve of them to a sheet, and a digitiser card from a British company, Compu-Tech, turned each sheet into an Apple II picture for him to clean up pixel by pixel.
He wanted the weight to show. Animation drawn without a reference had always looked wrong to him: “You could see that they had no weight and they never quite looked right. My vision was to have a character who felt fluid and lifelike so that players would feel suspense, knowing if they moved too far, they could fall into spikes and that it would really hurt.”
The prince became the yardstick for everything that followed. COMPUTE!’s beginner’s guide of January 1994 called the game “widely considered a milestone in the genre” and “a stunning showcase of rotoscoped animation, featuring incredibly fluid and lifelike character animation”. Amiga Computing was still recommending it as an alternative to Flashback in the summer of 1994, “even if it is showing signs of old age”.
Another World (1991)
Éric Chahi’s Another World — Out of This World in North America — used the same method with a different result on screen: every traced frame was redrawn as flat polygons rather than pixels. Chahi describes his equipment as “a camcorder, a genlock and a video recorder”, and the work as tense: “each video image was copied with polygons manually under the editor. I had to be as quick as possible as the video player would not stay in pause for long.” He kept the technique for the movements “linked to realism”, above all in the introduction, and filmed a scale model for the car’s skid. Club Nintendo’s coverage of the Super Nintendo version explained that Chahi himself “was photographed in various poses” and that the pictures were traced to make the hero.
The polygons made the animation small. The One’s preview in October 1991 reported that the introduction “requires just 70 Kilobytes for the animation data, and 15 Kilobytes for the program — that’s just 95 Kilobytes in total. An animation of similar complexity and length rendered with traditional bitmapped artwork would take up an entire disk!” Interplay’s catalogue copy for the Amiga release put the two ideas side by side: “The use of polygon graphics allows the game to generate real-time, rotoscoped animation in fluid cinematic zooms, pans, close-ups, and scaling.”
Flashback (1992)
Delphine Software’s Flashback went back to drawn sprites and made the frame rate the selling point. Edge’s account of its making names the art team, Denis Mercier, Christian Robert and Thierry Perreau, and describes a method that was, in the magazine’s words, “about as arduous a take on rotoscoping as you could imagine”. The team filmed one of their number going through the moves in front of a white wall. They then ran the footage on a television, frame by frame, traced the figure’s silhouette onto a transparency taped to the screen, taped the transparency to a computer monitor and traced it again in Deluxe Paint. The programmer Philippe Chastel remembered a total of 1,500 frames, 800 of them for the hero, Conrad, and the designer Paul Cuisset spoke of “crates of transparencies”. The method had one advantage the team had not expected: several artists could work on the same character without their styles showing. When the work wore them down, a visit from Mechner himself, who “went into ecstasies” about it, kept them going.
Delphine made 24 frames a second the headline. Amiga Format’s preview in March 1993 reported “a main character animated at a rate of 24 frames per second — which is the same as most animated movies”, and U.S. Gold’s advertisement in Computer Gaming World spoke in the first person: “We filmed real actors in motion. Then we brought everything to life on the computer through rotoscoping, the digitization and retouching of live action film — at 24 frames a second!”
Reviewers agreed. Computer Gaming World found “impressive animation derived from 24 frames-per-second rotoscoping — a truly uncanny thing to watch! Conrad jumps, rolls, twists and runs with ease and grace.” AmigaWorld drew the line between the two Delphine games: “Gone are the earlier game’s polygon constructs; they’ve been replaced with rotoscoped actors and hand-drawn backdrops.” COMPUTE! called the technique “similar to that used in Jordan Mechner’s Prince of Persia series”, and Amiga Power, choosing Flashback as one of its games of 1993, mentioned “the rotoscoped characters that move like real people”.
Rotoscoping and digitisation
The two are easy to confuse because both start with a camera. What differs is what reaches the screen.
| Technique | What reaches the screen | Examples |
|---|---|---|
| Rotoscoping | A drawing an artist made over each filmed frame | Karateka, Prince of Persia, Another World, Flashback |
| Digitisation | The video picture itself, captured and retouched | Mortal Kombat |
Mortal Kombat shows the difference. Its makers told SNES Force in 1993 that the fighters’ video images were captured from a camera onto a PC and then touched up dot by dot; no artist redrew them. U.S. Gold’s Flashback advert blurs the line with “the digitization and retouching of live action film”, but Edge’s account of how the game was made shows every frame being traced by hand.
Later history
Mechner used the technique once more, on a larger scale. For The Last Express (1997), set on the Orient Express, his company filmed professional actors against a blue screen and turned the footage into drawings. “In order to rotoscope that many frames, we had to automate it,” he told Wireframe; the aim was something “resembling a kind of pen and ink drawing” rather than full-motion video. PC Zone expected an effect “similar to the animation seen in Jordan Mechner’s classic Prince of Persia”, and Computer Gaming World’s review praised its “clever use of animation based on live-action footage (rotoscoping)”. By then 3D games were capturing movement directly as data; see motion capture.
Sources
- Max Fleischer, US patent 1,242,674, “Method of producing moving-picture cartoons”, filed 6 December 1915, granted 9 October 1917 (web, via Google Patents): the method and the quoted phrase. https://patents.google.com/patent/US1242674A/en
- “Turning back time”, Wireframe issue 37, April 2020, pp. 18–23: Mechner on Disney animation; Fleischer, Out of the Inkwell and Dave Fleischer; Snow White; filming Karateka on Super 8; the VHS, 35mm and digitiser process for Prince of Persia; Compu-Tech; weight and suspense; The Last Express.
- Amiga Format issue 33, April 1992: digitiser feature, the definition and Prince of Persia. Issue 44, March 1993: Flashback preview, already “on the shelves in France”. Issue 45, April 1993: Flashback review.
- Computer Gaming World issue 20, January 1985: readers’ poll listing Karateka.
- Brøderbund advertisement, “The making of Karateka”, Ahoy! issue 24, December 1985, and COMPUTE! December 1985.
- Enter vol. 2 no. 7, May 1985: Karateka review.
- COMPUTE! January 1994, “Getting Started With” supplement, pp. S-1–S-2: Prince of Persia; and Scott A. May’s Flashback review, pp. 144–145.
- Amiga Computing issue 76, August 1994: Flashback budget re-release, with Prince of Persia as an alternative.
- Éric Chahi, Another World official site, “Making of” page (web, secondary): the camcorder, genlock and video recorder, copying frames in polygons, the scale-model car and the introduction. https://www.anotherworld.fr/anotherworld_uk/page_realisation.htm
- Club Nintendo (UK) vol. 5 no. 1, 1993: Another World on the Super Nintendo; Chahi photographed and traced.
- The One issue 37, October 1991, p. 10: Another World preview and the 95K introduction.
- AC’s Guide to the Commodore Amiga, Summer 1992: Interplay’s catalogue entry for Out of This World.
- “The making of Flashback”, Edge issue 163, June 2006: the art team, the transparency method, Deluxe Paint, 1,500 frames and Mechner’s visit.
- Computer Gaming World issue 108, July 1993: U.S. Gold advertisement for Flashback. Issue 111, October 1993: Flashback review.
- AmigaWorld vol. 9 no. 9, September 1993: Flashback compared with Out of This World.
- Amiga Power issue 32, December 1993: games of the year.
- SNES Force issue 3, September 1993, p. 9: the Mortal Kombat makers on capturing and retouching video.
- PC Zone issue 47, February 1997: The Last Express preview. Computer Gaming World issue 156, July 1997: The Last Express review.