Special effects are shaping our world
Whether it's the curve of a flying football in a console game, or the clash of armies in a film about ancient civilisations, you can be guaranteed that plenty of scientific theory, technology and imagination have gone into those effects that you see on your screen.
From its earliest days, cinema has relied on visual magic ("smoke and mirrors") to produce illusions and trick effects, but special effects have come a long way in today's video games, films and television.
The earliest effects were produced inside the camera ("in-camera effects"), or were created by using miniatures, back projection, or matte paintings. Optical effects came slightly later, using film, light, shadow, lenses or chemical processes to produce the film effects.
Examples of these optical effects in the cinema include film titles, fades, dissolves, bluescreen, double exposures and zooms.
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The rise of CGI
With the arrival of modern digital film-making tools in the 1990s, film directors made much greater use of computer-generated or computer graphics imagery (CGI). Nowadays directors and games developers make a distinction between:
- "Special effects" (on-set mechanical effects and in-camera optical effects) and
- "Visual effects" (done in digital post-production)
CGI is now at the fore in special effects, from flight simulators to full-feature computer animations such as "Toy Story". It gives film-makers much greater control, and means many amazing effects can be created more safely and convincingly – often at much lower costs too.
Famous examples of CGI in recent films include:
- "Gladiator" - many of its large-scale crowds and battles featured thousands of CGI extras to save money and time (as well as ensuring safety when dealing with those computer-generated tigers!)
- "I, Robot" - including battle scenes between live humans and CGI robots
- "The Day After Tomorrow" - the designers had to simluate forces of extreme weather with the help of video references and accurate meteorological facts
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Games creators
Dublin-based company Havok is a world leader in this field. It develops software tools for film-makers and games creators to reach new standards of realism - and that means knowing a great deal of physics.
This type of software is sometimes called "middleware". Havok's middleware has been used to create more than 150 computer games, including best-selling titles such as Assassin's Creed and Halo 3, the Xbox 360 game.
The company's special effects system "Havok Physics" has been used to simulate large numbers of interacting objects in films: such as:
- Troy
- Charlie and the Chocolate Factory
- X-Men: The Last Stand
- Harry Potter and the Order Of The Phoenix
- The Chronicles of Narnia: Prince Caspian
At the heart of it all is a good knowledge of physics and maths, in order to make effects that obey the laws of the real world, such as realistic-looking explosions.
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The science of cinema
In fact, the reason why the human eye sees the individual frames of a video game or a movie as smooth, flowing action is due to research into a phenomenon called "persistence of vision".
This was first described in 1824 by physician Peter Mark Roget (who also went on to create Roget's Thesaurus). His groundbreaking paper on the subject was titled "Explanation of an optical deception in the appearance of the spokes of a wheel when seen through vertical apertures".
While Roget's explanation might have been wrong, his pioneering work on the illusion of motion was an important turning point in the history of film. It may have influenced the development of animation devices that were forerunners of cinematography. These include the Thaumatrope, the Phenakistiscope and the Zoetrope - all toys that produce an illusion of action from a rapid succession of static pictures.
A film or video game is also made up of a series of individual images, or frames. When these are shown rapidly in succession, the viewer has the illusion that motion is occurring, due to persistence of vision.
Basically the human eye retains the image for a fraction of a second after the source has been removed, so at these speeds you cannot detect the flickering between frames.
Films are shown at 24 frames per second in the cinema. In television it is 25 frames per second in the PAL system in Europe, or 30 frames per second in NTSC in the US (or 29.97 to be precise).
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Cinematography in science
While scientists and inventors came up with cinematography, cinematography in turn is also used by them to unearth phenomena that are usually hidden.
In time-lapse photography, for example, each film frame is captured at a rate much slower than it will be played back. So when it is then played at normal speed, time appears to be moving faster and thus "lapsing" – giving a better picture of some long-term trends.
If you set a camera to expose one frame every minute for four hours, and then show that footage at 24 frames per second, this compresses the event that took place in four hours into just 10 seconds.
The opposite of time-lapse photography is high-speed photography, the science of taking pictures of very fast phenomena.
Its first practical application was Eadweard Muybridge's 1878 investigation into whether horses' feet were actually all off the ground at once during a trot. Muybridge used a line of cameras that were attached to trip-wires and were triggered by the horse's hooves.
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Learn more
- Find out more about Havok's work
- Read about the history of art forms and inventions that led up to cinematography, from ancient cave paintings to the camera obscura
- See a computer animation that recreates Muybridge's horse photography experiments