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#2568. What does the medical term Humectant mean?

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#6347.

2494) Metal Detector

Gist

Metal detectors use electromagnetic fields to find hidden metal, with major uses in security (airports, events for weapons), hobby/recreation (treasure hunting, coin collecting), industry (quality control in food/pharma, construction for pipes/wires), and archaeology/recovery (locating artifacts, landmines). They range from handheld wands to large walk-through arches, alerting users with sound or visual cues when metal is detected.

Metal detectors detect any conductive metal by sensing disruptions in their electromagnetic field, finding everything from weapons and coins to jewelry and tools, distinguishing between easier-to-detect ferrous (iron-based) and harder-to-detect non-ferrous (like aluminum, copper) metals, with sensitivity adjusted for different uses like security or treasure hunting.

Summary

A metal detector is an instrument that detects the nearby presence of metal. Metal detectors are useful for finding metal objects on the surface, underground, and under water. A metal detector typically consists of a control box, an adjustable shaft, and a variable-shaped pickup coil. When the coil nears metal, the control box signals its presence with a tone, numerical reading, light, or needle movement. Signal intensity typically increases with proximity or metal size and composition. A common type are stationary "walk through" metal detectors used at access points in prisons, courthouses, airports and psychiatric hospitals to detect concealed metal weapons on a person's body.

The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field. If a piece of electrically conductive metal is close to the coil, eddy currents will be induced (inductive sensor) in the metal, and this produces a magnetic field of its own. If another coil is used to measure the magnetic field (acting as a magnetometer), the change in the magnetic field due to the metallic object can be detected.

The first industrial metal detectors came out in the 1960s, and were used for finding minerals, among other things. Metal detectors help find land mines. They also detect weapons like knives and guns, which is important for airport security. People most commonly use them to search for buried objects, like in archaeology and treasure hunting. Metal detectors are also used to detect foreign bodies in food, and in the construction industry to detect steel reinforcing bars in concrete and pipes and wires buried in walls and floors.

Details

Mention the words metal detector and you'll get completely different reactions from different people. For instance, some people think of combing a beach in search of coins or buried treasure. Other people think of airport security, or the handheld scanners at a concert or sporting event.

The fact is that all of these scenarios are valid. Metal-detector technology is a huge part of our lives, with a range of uses that spans from leisure to work to safety. The metal detectors in airports, office buildings, schools, government agencies and prisons help ensure that no one is bringing a weapon onto the premises. Consumer-oriented metal detectors provide millions of people around the world with an opportunity to discover hidden treasures (along with lots of junk).

In this article, you'll learn about metal detectors and the various technologies they use. Our focus will be on consumer metal detectors, but most of the information also applies to mounted detection systems, like the ones used in airports, as well as handheld security scanners.

Anatomy of a Metal Detector

A typical metal detector is light-weight and consists of just a few parts:

Stabilizer (optional) - used to keep the unit steady as you sweep it back and forth
Control box - contains the circuitry, controls, speaker, batteries and the microprocessor
Shaft - connects the control box and the coil; often adjustable so you can set it at a comfortable level for your height
Search coil - the part that actually senses the metal; also known as the "search head," "loop" or "antenna"

Most systems also have a jack for connecting headphones, and some have the control box below the shaft and a small display unit above.

Operating a metal detector is simple. Once you turn the unit on, you move slowly over the area you wish to search. In most cases, you sweep the coil (search head) back and forth over the ground in front of you. When you pass it over a target object, an audible signal occurs. More advanced metal detectors provide displays that pinpoint the type of metal it has detected and how deep in the ground the target object is located.

Metal detectors use one of three technologies:

* Very low frequency (VLF)
* Pulse induction (PI)
* Beat-frequency oscillation (BFO)

In the following sections, we will look at each of these technologies in detail to see how they work.

VLF Technology

Very low frequency (VLF), also known as induction balance, is probably the most popular detector technology in use today. In a VLF metal detector, there are two distinct coils:

* Transmitter coil - This is the outer coil loop. Within it is a coil of wire. Electricity is sent along this wire, first in one direction and then in the other, thousands of times each second. The number of times that the current's direction switches each second establishes the frequency of the unit.
* Receiver coil - This inner coil loop contains another coil of wire. This wire acts as an antenna to pick up and amplify frequencies coming from target objects in the ground.
The current moving through the transmitter coil creates an electromagnetic field, which is like what happens in an electric motor. The polarity of the magnetic field is perpendicular to the coil of wire. Each time the current changes direction, the polarity of the magnetic field changes. This means that if the coil of wire is parallel to the ground, the magnetic field is constantly pushing down into the ground and then pulling back out of it.

As the magnetic field pulses back and forth into the ground, it interacts with any conductive objects it encounters, causing them to generate weak magnetic fields of their own. The polarity of the object's magnetic field is directly opposite the transmitter coil's magnetic field. If the transmitter coil's field is pulsing downward, the object's field is pulsing upward.

The receiver coil is completely shielded from the magnetic field generated by the transmitter coil. However, it is not shielded from magnetic fields coming from objects in the ground. Therefore, when the receiver coil passes over an object giving off a magnetic field, a small electric current travels through the coil. This current oscillates at the same frequency as the object's magnetic field. The coil amplifies the frequency and sends it to the control box of the metal detector, where sensors analyze the signal.

The metal detector can determine approximately how deep the object is buried based on the strength of the magnetic field it generates. The closer to the surface an object is, the stronger the magnetic field picked up by the receiver coil and the stronger the electric current generated. The farther below the surface, the weaker the field. Beyond a certain depth, the object's field is so weak at the surface that it is undetectable by the receiver coil.

In the next section, we'll see how a VLF metal detector distinguishes between different types of metals.

VLF Phase Shifting

How does a VLF metal detector distinguish between different metals? It relies on a phenomenon known as phase shifting. Phase shift is the difference in timing between the transmitter coil's frequency and the frequency of the target object. This discrepancy can result from a couple of things:

* Inductance - An object that conducts electricity easily (is inductive) is slow to react to changes in the current. You can think of inductance as a deep river: Change the amount of water flowing into the river and it takes some time before you see a difference.
* Resistance - An object that does not conduct electricity easily (is resistive) is quick to react to changes in the current. Using our water analogy, resistance would be a small, shallow stream: Change the amount of water flowing into the stream and you notice a drop in the water level very quickly.

Basically, this means that an object with high inductance is going to have a larger phase shift, because it takes longer to alter its magnetic field. An object with high resistance is going to have a smaller phase shift.

Phase shift provides VLF-based metal detectors with a capability called discrimination. Since most metals vary in both inductance and resistance, a VLF metal detector examines the amount of phase shift, using a pair of electronic circuits called phase demodulators, and compares it with the average for a particular type of metal. The detector then notifies you with an audible tone or visual indicator as to what range of metals the object is likely to be in.

Many metal detectors even allow you to filter out (discriminate) objects above a certain phase-shift level. Usually, you can set the level of phase shift that is filtered, generally by adjusting a knob that increases or decreases the threshold. Another discrimination feature of VLF detectors is called notching. Essentially, a notch is a discrimination filter for a particular segment of phase shift. The detector will not only alert you to objects above this segment, as normal discrimination would, but also to objects below it.

Advanced detectors even allow you to program multiple notches. For example, you could set the detector to disregard objects that have a phase shift comparable to a soda-can tab or a small nail. The disadvantage of discrimination and notching is that many valuable items might be filtered out because their phase shift is similar to that of "junk." But, if you know that you are looking for a specific type of object, these features can be extremely useful.

PI Technology

A less common form of metal detector is based on pulse induction (PI). Unlike VLF, PI systems may use a single coil as both transmitter and receiver, or they may have two or even three coils working together. This technology sends powerful, short bursts (pulses) of current through a coil of wire. Each pulse generates a brief magnetic field. When the pulse ends, the magnetic field reverses polarity and collapses very suddenly, resulting in a sharp electrical spike. This spike lasts a few microseconds (millionths of a second) and causes another current to run through the coil. This current is called the reflected pulse and is extremely short, lasting only about 30 microseconds. Another pulse is then sent and the process repeats. A typical PI-based metal detector sends about 100 pulses per second, but the number can vary greatly based on the manufacturer and model, ranging from a couple of dozen pulses per second to over a thousand.

If the metal detector is over a metal object, the pulse creates an opposite magnetic field in the object. When the pulse's magnetic field collapses, causing the reflected pulse, the magnetic field of the object makes it take longer for the reflected pulse to completely disappear. This process works something like echoes: If you yell in a room with only a few hard surfaces, you probably hear only a very brief echo, or you may not hear one at all; but if you yell in a room with a lot of hard surfaces, the echo lasts longer. In a PI metal detector, the magnetic fields from target objects add their "echo" to the reflected pulse, making it last a fraction longer than it would without them.

A sampling circuit in the metal detector is set to monitor the length of the reflected pulse. By comparing it to the expected length, the circuit can determine if another magnetic field has caused the reflected pulse to take longer to decay. If the decay of the reflected pulse takes more than a few microseconds longer than normal, there is probably a metal object interfering with it.

The sampling circuit sends the tiny, weak signals that it monitors to a device call an integrator. The integrator reads the signals from the sampling circuit, amplifying and converting them to direct current (DC). The direct current's voltage is connected to an audio circuit, where it is changed into a tone that the metal detector uses to indicate that a target object has been found.

PI-based detectors are not very good at discrimination because the reflected pulse length of various metals are not easily separated. However, they are useful in many situations in which VLF-based metal detectors would have difficulty, such as in areas that have highly conductive material in the soil or general environment. A good example of such a situation is salt-water exploration. Also, PI-based systems can often detect metal much deeper in the ground than other systems.

BFO Technology

The most basic way to detect metal uses a technology called beat-frequency oscillator (BFO). In a BFO system, there are two coils of wire. One large coil is in the search head, and a smaller coil is located inside the control box. Each coil is connected to an oscillator that generates thousands of pulses of current per second. The frequency of these pulses is slightly offset between the two coils.

As the pulses travel through each coil, the coil generates radio waves. A tiny receiver within the control box picks up the radio waves and creates an audible series of tones (beats) based on the difference between the frequencies.

If the coil in the search head passes over a metal object, the magnetic field caused by the current flowing through the coil creates a magnetic field around the object. The object's magnetic field interferes with the frequency of the radio waves generated by the search-head coil. As the frequency deviates from the frequency of the coil in the control box, the audible beats change in duration and tone.

BFO Technology

The simplicity of BFO-based systems allows them to be manufactured and sold for a very low cost. But these detectors do not provide the level of control and accuracy provided by VLF or PI systems.

Buried Treasure

Metal detectors are great for finding buried objects. But typically, the object must be within a foot or so of the surface for the detector to find it. Most detectors have a normal maximum depth somewhere between 8 and 12 inches (20 and 30 centimeters). The exact depth varies based on a number of factors:

The type of metal detector - The technology used for detection is a major factor in the capability of the detector. Also, there are variations and additional features that differentiate detectors that use the same technology. For example, some VLF detectors use higher frequencies than others, while some provide larger or smaller coils. Plus, the sensor and amplification technology can vary between manufacturers and even between models offered by the same manufacturer.

* The type of metal in the object - Some metals, such as iron, create stronger magnetic fields than others.
* The size of the object - A dime is much harder to detect at deep levels than a quarter.
* The makeup of the soil - Certain minerals are natural conductors and can seriously interfere with the metal detector.
* The object's halo - When certain types of metal objects have been in the ground for a long time, they can actually increase the conductivity of the soil around them.
* Interference from other objects - This can be items in the ground, such as pipes or cables, or items above ground, like power lines.

Hobbyist metal detecting is a fascinating world with several sub-groups. Here are some of the more popular activities:

* Coin shooting - looking for coins after a major event, such as a ball game or concert, or just searching for old coins in general
* Prospecting - searching for valuable metals, such as gold nuggets
* Relic hunting - searching for items of historical value, such as weapons used in the U.S. Civil War
* Treasure hunting - researching and trying to find caches of gold, silver or anything else rumored to have been hidden somewhere
* Many metal-detector enthusiasts join local or national clubs that provide tips and tricks for hunting. Some of these clubs even sponsor organized treasure hunts or other outings for their members.

Detective Work

In addition to recreational use, metal detectors serve a wide range of utilitarian functions. Mounted detectors usually use some variation of PI technology, while many of the basic handheld scanners are BFO-based.

Some nonrecreational applications for metal detectors are:

* Airport security - screen people before allowing access to the boarding area and the plane (see How Airport Security Works)
* Building security - screen people entering a particular building, such as a school, office or prison
* Event security - screen people entering a sporting event, concert or other large gathering of people
* Item recovery - help someone search for a lost item, such as a piece of jewelry
* Archaeological exploration - find metallic items of historical significance
* Geological research - detect the metallic composition of soil or rock formations

Manufacturers of metal detectors are constantly tuning the process to make their products more accurate, more sensitive and more versatile. On the next page, you will find links to the manufacturers, as well as clubs and more information on metal detecting as a hobby.

Additional Information

A metal detector is an electronic device that finds metal objects nearby. These devices are very useful for discovering metal pieces hidden inside other objects. They can also find metal items buried underground. Most metal detectors have a handheld part with a special sensor. You can sweep this sensor over the ground or other things. If the sensor gets close to metal, you will hear a changing sound in earphones. Sometimes, a needle on a display will move. The closer the metal is, the louder the sound or the higher the needle goes.

Another common type of metal detector is a "walk-through" scanner. These are used for security checks at places like airports. They help find hidden metal weapons on a person's body.

The basic idea behind a metal detector is simple. It uses an electronic circuit to create an alternating current. This current goes through a coil, which then makes an invisible magnetic field. If a piece of metal that conducts electricity comes close to this coil, tiny electric currents called eddy currents are created in the metal. These eddy currents then make their own magnetic field. The metal detector has another coil that measures these magnetic fields. When the magnetic field changes because of a metal object, the detector senses it.

History and Uses of Metal Detectors

The first industrial metal detectors were made in the 1960s. They quickly became popular for finding minerals and for other industrial jobs.

Finding Hidden Treasures and More

Metal detectors have many interesting uses today:

* Finding landmines: They help locate dangerous land mines left behind after wars.
* Security: They are used to find weapons like knives and guns, especially at airports and other secure locations.
* Exploring the Earth: Scientists use them for geophysical prospecting, which means exploring the Earth's surface for minerals.
* Archaeology: Archaeologists use them to find old artifacts buried underground.
* Treasure hunting: Many people use metal detectors as a hobby to search for lost coins, jewelry, and other treasures.

Metal Detectors in Everyday Life

Metal detectors are also used in other important ways:

* Food safety: They help find foreign objects, like small pieces of metal, in food products. This keeps our food safe to eat.
* Construction: In the construction industry, they find steel reinforcing bars inside concrete. They can also locate pipes and wires hidden in walls and floors.

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#5941. What does the noun legroom mean?

#5942. What does the noun legume mean?

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#9852.

Hi,

2706.

2493) Animation

Gist

Animation is the art of creating the illusion of motion by rapidly displaying a sequence of static, slightly different images, often used in entertainment to bring characters to life. It encompasses traditional hand-drawn techniques, computer-generated imagery (CGI), and stop-motion, with 2D, 3D, and digital methods being dominant today. Key principles like timing, spacing, and squash-and-stretch ensure realistic or stylized motion, while software allows for efficient production.

The term 'animation' is derived from the Japanese word 'anime,' which can be translated as “to move” or “to give life”. The first animated “film” was made by a French cartoonist called Émile Cohl. This was the origin of animation; now, let's discuss the definition of animation.

Summary

Animation is a filmmaking technique whereby pictures are generated or manipulated to create moving images. In traditional animation, images are drawn or painted by hand on transparent celluloid sheets to be photographed and exhibited on film. Animation has been recognized as an artistic medium, specifically within the entertainment industry. Many animations are either traditional animations or computer animations made with computer-generated imagery (CGI). Stop motion animation, in particular claymation, is also prominent alongside these other forms, albeit to a lesser degree.

Animation is contrasted with live action, although the two do not exist in isolation. Many filmmakers have produced films that are a hybrid of the two. As CGI increasingly approximates photographic imagery, filmmakers can relatively easily composite 3D animated visual effects (VFX) into their film, rather than using practical effects.

General overview

Computer animation can be very detailed 3D animation, while 2D computer animation (which may have the look of traditional animation) can be used for stylistic reasons, low bandwidth, or faster real-time renderings. Other common animation methods apply a stop motion technique to two- and three-dimensional objects like paper cutouts, puppets, or clay figures.

An animated cartoon, or simply a cartoon, is an animated film, usually short, that features an exaggerated style. This style is often inspired by comic strips, gag cartoons, and other non-animated art forms. Cartoons frequently include anthropomorphic animals, superheroes, or the adventures of human protagonists. The action often revolves around exaggerated physical humor, particularly in predator/prey dynamics (e.g. cats and mice, coyotes and birds), where violent pratfalls such as falls, collisions, and explosions occur, often in ways that would be lethal in the real life.

During the late 1980s, the term "cartoon" was shortened to toon, referring to characters in animated productions, or more specifically, cartoonishly-drawn characters. This term gained popularity first in 1988 with the live-action/animated hybrid film Who Framed Roger Rabbit, which introduced ToonTown, a world inhabited by various animated cartoon characters. In 1990, Tiny Toon Adventures embraced the classic cartoon spirit, introducing a new generation of cartoon characters. Then, in 1993, Animaniacs followed, featuring the three rubber-hose-styled Warner siblings, Yakko Warner, Wakko Warner, and Dot Warner, who are trapped in the 1930s, eventually escaped and found themselves in the Warner Bros. water tower in the 1990s.

The illusion of animation—as in motion pictures in general—has traditionally been attributed to the persistence of vision and later to the phi phenomenon and beta movement, but the exact neurological causes are still uncertain. The illusion of motion caused by a rapid succession of images that minimally differ from each other, with unnoticeable interruptions, is a stroboscopic effect. While animators traditionally used to draw each part of the movements and changes of figures on transparent cels that could be moved over a separate background, computer animation is usually based on programming paths between key frames to maneuver digitally created figures throughout a digitally created environment.

Analog mechanical animation media that rely on the rapid display of sequential images include the phenakistiscope, zoetrope, flip book, praxinoscope, and film. Television and video are popular electronic animation media that originally were analog and now operate digitally. For display on computers, technology such as the animated GIF and Flash animation were developed.

In addition to short films, feature films, television series, animated GIFs (Graphics Interchange Format), and other media dedicated to the display of moving images, animation is also prevalent in video games, motion graphics, user interfaces, and visual effects.

The physical movement of image parts through simple mechanics—for instance, moving images in magic lantern shows—can also be considered animation. The mechanical manipulation of three-dimensional puppets and objects to emulate living beings has a very long history in automata. Electronic automata were popularized by Disney as animatronics.

Details

Animation is the art of making inanimate objects appear to move. Animation is an artistic impulse that long predates the movies. History’s first recorded animator is Pygmalion of Greek and Roman mythology, a sculptor who created a figure of a woman so perfect that he fell in love with her and begged Venus to bring her to life. Some of the same sense of magic, mystery, and transgression still adheres to contemporary film animation, which has made it a primary vehicle for exploring the overwhelming, often bewildering emotions of childhood—feelings once dealt with by folktales.

Early history

The theory of the animated cartoon preceded the invention of the cinema by half a century. Early experimenters, working to create conversation pieces for Victorian parlors or new sensations for the touring magic-lantern shows, which were a popular form of entertainment, discovered the principle of persistence of vision. If drawings of the stages of an action were shown in fast succession, the human eye would perceive them as a continuous movement. One of the first commercially successful devices, invented by the Belgian Joseph Plateau in 1832, was the phenakistoscope, a spinning cardboard disk that created the illusion of movement when viewed in a mirror. In 1834 William George Horner invented the zoetrope, a rotating drum lined by a band of pictures that could be changed. The Frenchman Émile Reynaud in 1876 adapted the principle into a form that could be projected before a theatrical audience. Reynaud became not only animation’s first entrepreneur but, with his gorgeously hand-painted ribbons of celluloid conveyed by a system of mirrors to a theater screen, the first artist to give personality and warmth to his animated characters.

With the invention of sprocket-driven film stock, animation was poised for a great leap forward. Although “firsts” of any kind are never easy to establish, the first film-based animator appears to be J. Stuart Blackton, whose Humorous Phases of Funny Faces in 1906 launched a successful series of animated films for New York’s pioneering Vitagraph Company. Later that year, Blackton also experimented with the stop-motion technique—in which objects are photographed, then repositioned and photographed again—for his short film Haunted Hotel.

In France, Émile Cohl was developing a form of animation similar to Blackton’s, though Cohl used relatively crude stick figures rather than Blackton’s ambitious newspaper-style cartoons. Coinciding with the rise in popularity of the Sunday comic sections of the new tabloid newspapers, the nascent animation industry recruited the talents of many of the best-known artists, including Rube Goldberg, Bud Fisher (creator of Mutt and Jeff) and George Herriman (creator of Krazy Kat), but most soon tired of the fatiguing animation process and left the actual production work to others.

The one great exception among these early illustrators-turned-animators was Winsor McCay, whose elegant, surreal Little Nemo in Slumberland and Dream of the Rarebit Fiend remain pinnacles of comic-strip art. McCay created a hand-colored short film of Little Nemo for use during his vaudeville act in 1911, but it was Gertie the Dinosaur, created for McCay’s 1914 tour, that transformed the art. McCay’s superb draftsmanship, fluid sense of movement, and great feeling for character gave viewers an animated creature who seemed to have a personality, a presence, and a life of her own. The first cartoon star had been born.

McCay made several other extraordinary films, including a re-creation of The Sinking of the Lusitania (1918), but it was left to Pat Sullivan to extend McCay’s discoveries. An Australian-born cartoonist who opened a studio in New York City, Sullivan recognized the great talent of a young animator named Otto Messmer, one of whose casually invented characters—a wily black cat named Felix—was made into the star of a series of immensely popular one-reelers. Designed by Messmer for maximum flexibility and facial expressiveness, the round-headed, big-eyed Felix quickly became the standard model for cartoon characters: a rubber ball on legs who required a minimum of effort to draw and could be kept in constant motion.

Walt Disney

This lesson did not go unremarked by the young Walt Disney, then working at his Laugh-O-gram Films studio in Kansas City, Missouri. His first major character, Oswald the Lucky Rabbit, was a straightforward appropriation of Felix; when he lost the rights to the character in a dispute with his distributor, Disney simply modified Oswald’s ears and produced Mickey Mouse.

Far more revolutionary was Disney’s decision to create a cartoon with the novelty of synchronized sound. Steamboat Willie (1928), Mickey’s third film, took the country by storm. A missing element—sound—had been added to animation, making the illusion of life that much more complete, that much more magical. Later, Disney would add carefully synchronized music (The Skeleton Dance, 1929), three-strip Technicolor (Flowers and Trees, 1932), and the illusion of depth with his multiplane camera (The Old Mill, 1937). With each step, Disney seemed to come closer to a perfect naturalism, a painterly realism that suggested academic paintings of the 19th century. Disney’s resident technical wizard was Ub Iwerks, a childhood friend who followed Disney to Hollywood and was instrumental in the creation of the multiplane camera and the synchronization techniques that made the Mickey Mouse cartoons and the Silly Symphonies series seem so robust and fully dimensional.

For Disney, the final step was, of course, Snow White and the Seven Dwarfs (1937). Although not the first animated feature, it was the first to use up-to-the-minute techniques and the first to receive a wide, Hollywood-style release. Instead of amusing his audience with talking mice and singing cows, Disney was determined to give them as profound a dramatic experience as the medium would allow; he reached into his own troubled childhood to interpret this rich fable of parental abandonment, sibling rivalry, and the onrush of adult passion.

With his increasing insistence on photographic realism in films such as Pinocchio (1940), Fantasia (1940), Dumbo (1941), and Bambi (1942), Disney perversely seemed to be trying to put himself out of business by imitating life too well. That was not the temptation followed by Disney’s chief rivals in the 1930s, all of whom came to specialize in their own kind of stylized mayhem.

The Fleischer brothers

Max and Dave Fleischer had become successful New York animators while Disney was still living in Kansas City. The Fleischers invented the rotoscoping process, still in use today, in which a strip of live-action footage can be traced and redrawn as a cartoon. The Fleischers exploited this technique in their pioneering series Out of the Inkwell (1919–29). It was this series, with its lively interaction between human and drawn figures, that Disney struggled to imitate with his early Alice cartoons.

But if Disney was Mother Goose and Norman Rockwell, the Fleischers (Max produced, Dave directed) were stride piano and red whiskey. Their extremely urban, overcrowded, sexually suggestive, and frequently nightmarish work—featuring the curvaceous torch singer Betty Boop and her two oddly infantile colleagues, Bimbo the Dog and Koko the Clown—charts a twisty route through the American subconscious of the 1920s and ’30s, before collapsing into Disneyesque cuteness with the features Gulliver’s Travels (1939) and Mr. Bug Goes to Town (1941; also released as Hoppity Goes to Town). The studio’s mainstay remained the relatively impersonal Popeye series, based on the comic strip created by Elzie Segar. The spinach-loving sailor was introduced as a supporting player in the Betty Boop cartoon Popeye the Sailor (1933) and quickly ascended to stardom, surviving through 105 episodes until the 1942 short Baby Wants a Bottleship, when the Fleischer studio collapsed and rights to the character passed to Famous Studios.

“Termite Terrace”

Less edgy than the Fleischers but every bit as anarchic were the animations produced by the Warner Bros. cartoon studio, known to its residents as “Termite Terrace.” The studio was founded by three Disney veterans, Rudolph Ising, Hugh Harmon, and Friz Freleng, but didn’t discover its identity until Tex Avery, fleeing the Walter Lantz studio at Universal, joined the team as a director. Avery was young and irreverent, and he quickly recognized the talent of staff artists such as Chuck Jones, Bob Clampett, and Bob Cannon. Together they brought a new kind of speed and snappiness to the Warners product, beginning with Gold Diggers of ’49 (1936). With the addition of director Frank Tashlin, musical director Carl W. Stalling, and voice interpreter Mel Blanc, the team was in place to create a new kind of cartoon character: cynical, wisecracking, and often violent, who, refined through a series of cartoons, finally emerged as Bugs Bunny in Tex Avery’s A Wild Hare (1940). Other characters, some invented and some reinterpreted, arrived, including Daffy Duck, Porky Pig, Tweety and Sylvester, Pepe LePew, Foghorn Leghorn, Road Runner, and Wile E. Coyote. Avery left Warner Brothers and in 1942 joined Metro-Goldwyn-Mayer’s moribund animation unit, where, if anything, his work became even wilder in films such as Red Hot Riding Hood (1943) and Bad Luck Blackie (1949).

Animation in Europe

In Europe animation had meanwhile taken a strikingly different direction. Eschewing animated line drawings, filmmakers experimented with widely different techniques: in Russia and later in France, Wladyslaw Starewicz (also billed as Ladislas Starevitch), a Polish art student and amateur entomologist, created stop-motion animation with bugs and dolls; among his most celebrated films are The Cameraman’s Revenge (1912), in which a camera-wielding grasshopper uses the tools of his trade to humiliate his unfaithful wife, and the feature-length The Tale of the Fox (1930), based on German folktales as retold by Johann Wolfgang von Goethe. A Russian working in France, Alexandre Alexeïeff, developed the pinscreen, a board perforated by some 500,000 pins that could be raised or lowered, which created patterns of light and shadow that gave the effect of an animated steel engraving. It took Alexeïeff two years to create A Night on Bald Mountain (1933), which used the music of Modest Mussorgsky; in 1963 Nikolay Gogol was the source of his most widely celebrated film, the dark fable The Nose.

Inspired by the shadow puppet theater of Thailand, Germany’s Lotte Reiniger employed animated silhouettes to create elaborately detailed scenes derived from folktales and children’s books. Her The Adventures of Prince Achmed (1926) may have been the first animated feature; it required more than two years of patient work and earned her the nickname “The Mistress of Shadows,” as bestowed on her by Jean Renoir. Her other works include Dr. Dolittle and His Animals (1928) and shorts based on musical themes by Wolfgang Amadeus Mozart (Papageno, 1935; adapted from The Magic Flute), Gaetano Donizetti (L’elisir d’amore, 1939; “The Elixir of Love”), and Igor Stravinsky (Dream Circus, 1939; adapted from Pulcinella). In the 1950s Reiniger moved to England, where she continued to produce films until her retirement in the ’70s.

Another German-born animator, Oskar Fischinger, took his work in a radically different direction. Abandoning the fairy tales and comic strips that had inspired most of his predecessors, Fischinger took his inspiration from the abstract art that dominated the 1920s. At first he worked with wax figures animated by stop motion, but his most significant films are the symphonies of shapes and sounds he called “colored rhythms,” created from shifting color fields and patterns matched to music by classical composers. He became fascinated by color photography and collaborated on a process called Gasparcolor, which, as utilized in his 1935 film Composition in Blue, won a prize at that year’s Venice Film Festival. The following year, he immigrated to Hollywood, where he worked on special effects for a number of films and was the initial designer of the Toccata and Fugue sequence in Walt Disney’s Fantasia (1940). The Disney artists modified his designs, however, and he asked that his name be removed from the finished film. Through the 1940s and ’50s he balanced his work between experimental films such as Motion Painting No. 1 (1947) and commercials, and he retired from animation in 1961 to devote himself to painting.

Fischinger’s films made a deep impression on the Scottish design student Norman McLaren, who began experimenting with cameraless films—with designs drawn directly on celluloid—as early as 1933 (Seven Till Five). A restless and brilliant researcher, he went to work for John Grierson at the celebrated General Post Office (GPO) Film Unit in London and followed Grierson to Canada in 1941, shortly after the founding of the National Film Board. Supported by government grants, he was able to play out his most radical creative impulses, using watercolors, crayons, and paper cutouts to bring abstract designs to flowing life. Attracted by the possibilities of stop-motion animation, he was able to turn inanimate objects into actors (A Chairy Tale, 1957) and actors into inanimate objects (Neighbours, 1952), a technique he called “pixellation.”

The international success of McLaren’s work (he won an Oscar for Neighbours) opened the possibilities for more personal forms of animation in America. John Hubley, an animator who worked for Disney studios on Snow White, Pinocchio, and Fantasia, left the Disney organization in 1941 and joined the independent animation company United Productions of America in 1945. Working in a radically simplified style, without the depth effects and shading of the Disney cartoons, Hubley created the nearsighted character Mister Magoo for the 1949 short Ragtime Bear. He and his wife, Faith, formed their own studio, Storyboard Productions, in 1955, and they collaborated on a series of increasingly poetic narrative films. They won Oscars for Moonbird (1959) and The Hole (1962). The Hubleys also created a much-admired series of short films based on the jazz improvisations of Dizzy Gillespie, Quincy Jones, and Benny Carter.

The evolution of animation in Eastern Europe was impeded by World War II, but several countries—in particular Poland, Hungary, and Romania—became world leaders in the field by the 1960s. Włodzimierz Haupe and Halina Bielinska were among the first important Polish animators; their Janosik (1954) was Poland’s first animated film, and their Changing of the Guard (1956) employed the stop-action gimmick of animated matchboxes. The collaborative efforts of Jan Lenica and Walerian Borowczyk foresaw the bleak themes and absurdist trends of the Polish school of the 1960s; such films as Był sobie raz… (1957; Once Upon a Time…), Nagrodzone uczucie (1957; Love Rewarded), and Dom (1958; The House) are surreal, pessimistic, plotless, and characterized by a barrage of disturbing images. Borowczyk and Lenica, each of whom went on to a successful solo career, helped launch an industry that produced as many as 120 animated films per year by the early ’60s. Animators such as Miroslaw Kijowicz, Daniel Szczechura, and Stefan Schabenbeck were among the leaders in Polish animation during the second half of the 20th century.

Nontraditional forms

Eastern Europe also became the center of puppet animation, largely because of the sweetly engaging, folkloric work of Jiří Trnka. Based on a Hans Christian Andersen story, Trnka’s The Emperor’s Nightingale became an international success when it was fitted with narration by Boris Karloff and released in 1948. His subsequent work includes ambitious adaptations of The Good Soldier Schweik (1954) and A Midsummer Night’s Dream (1959).

Born in Hungary, George Pal worked as an animator in Berlin, Prague, Paris, and the Netherlands before immigrating to the United States in 1939. There he contracted with Paramount Pictures to produce the Puppetoons series, perhaps the most popular and accomplished puppet animations to be created in the United States. A dedicated craftsman, Pal would produce up to 9,000 model figures for films such as Tulips Shall Grow, his 1942 anti-Nazi allegory. Pal abandoned animation for feature film production in 1947, though in films such as The War of the Worlds (1953) he continued to incorporate elaborate animated special-effects sequences.

Animators in Czechoslovakia and elsewhere took the puppet technique down far darker streets. Jan Švankmajer, for example, came to animation from the experimental theater movement of Prague. His work combines human figures and stop-motion animation to create disturbingly carnal meditations on sexuality and mortality, such as the short Dimensions of Dialogue (1982) and the features Alice (1988), Faust (1994), and Conspirators of Pleasure (1996). Švankmajer’s most dedicated disciples are the Quay brothers, Stephen and Timothy, identical twins born in Philadelphia who moved to London to create a series of meticulous puppet animations steeped in the atmosphere and ironic fatalism of Eastern Europe. Their Street of Crocodiles (1986), obliquely based on the stories of Bruno Schulz, is a parable of obscure import in which a puppet is freed of his strings but remains enslaved by bizarre sexual impulses.

Nick Park, the creator of the Wallace and Gromit series, is the optimist’s answer to the Quay brothers—a stop-motion animator who creates endearing characters and cozy environments that celebrate the security and complacency of provincial English life. He and his colleagues at the British firm Aardman Animations, including founders Peter Lord and Dave Sproxton, have taken the traditionally child-oriented format of clay animation to new heights of sophistication and expressiveness.

More-traditional forms of line animation have continued to be produced in Europe by filmmakers such as France’s Paul Grimault (The King and the Bird, begun in 1948 and released in 1980), Italy’s Bruno Bozzetto (whose 1976 Allegro Non Troppo broadly parodied Fantasia), and Great Britain’s John Halas and Joy Batchelor (Animal Farm, 1955) and Richard Williams (Raggedy Ann and Andy, 1977). George Dunning’s Yellow Submarine (1968) made creative use of the visual motifs of the psychedelic era, luring young adults back to a medium that had largely been relegated to children.

A victim of rising production costs, full-figure, feature-length animation appeared to be dying off until two developments gave it an unexpected boost in the 1980s. The first was the Disney company’s discovery that the moribund movie musical could be revived and made palatable to contemporary audiences by adapting it to cartoon form (The Little Mermaid, 1989); the second was the development of computer animation technology, which greatly reduced expenses while providing for new forms of expression. Although most contemporary animated films use computer techniques to a greater or lesser degree, the finest, purest achievements in the genre are the work of John Lasseter, whose Pixar Animation Studios productions have evolved from experimental shorts, such as Luxor, Jr. (1986), to lush features, such as Toy Story (1995; the first entirely computer-animated feature-length film), A Bug’s Life (1998), Finding Nemo (2003), The Incredibles (2004), WALL-E (2008), and Up (2009). Computer techniques are commonly incorporated into traditional line animations, giving films such as Disney’s Mulan (1998) and Dreamworks’s The Road to El Dorado (2000) a visual sweep and dimensionality that would otherwise require countless hours of manual labor.

Contemporary developments

A century after its birth, animation continues to evolve. The most exciting developments are found on two distinct fronts: the anime (“animation”) of Japan and the prime-time television cartoons of the United States. An offspring of the dense, novelistic style of Japanese manga comic books and the cut-rate techniques developed for television production in 1960, anime such as Miyazaki Hayao’s Princess Mononoke (1997) are the modern equivalent of the epic folk adventures once filmed by Mizoguchi Kenji (The 47 Ronin, 1941) and Kurosawa Akira (Yojimbo, 1961; “The Bodyguard”). Kon Satoshi’s Perfect Blue (1997) suggests the early Japanese New Wave films of director Oshima Nagisa with its violent exploration of a media-damaged personality.

U.S. television animation, pioneered in the 1950s by William Hanna and Joseph Barbera (Yogi Bear, The Flintstones) was for years synonymous with primitive techniques and careless writing. But with the debut of The Simpsons in 1989, TV animation became home to a kind of mordant social commentary or outright absurdism (John Kricfalusi’s Ren and Stimpy) that was too pointedly aggressive for live-action realism. When Mike Judge’s Beavis and Butt-Head debuted on the MTV network in 1993, the rock-music cable channel discovered that cartoons could push the limits of censorship in ways no live-action television productions could. Following Judge’s success in 1997 were Trey Parker and Matt Stone with South Park, a series centered on foulmouthed kids growing up in the American Rocky Mountain West and rendered in a flat, cutout animation style that would have looked primitive in 1906. The spiritual father of the new television animation is Jay Ward, whose Rocky and His Friends, first broadcast in 1959, turned the threadbare television style into a vehicle for absurdist humor and adult satire.

Despite these boundary-pushing advances, full-figure, traditionally animated films continue to be produced, most notably by Don Bluth (An American Tale, 1986), a Disney dissident who moved his operation to Ireland, and Brad Bird, a veteran of Simpsons minimalism who progressed to the spectacular full technique of The Iron Giant (1999). As digital imaging techniques continue to improve in quality and affordability, it becomes increasingly difficult to draw a clear line between live action and animation. Films such as The Matrix (1999), Star Wars: Episode One (1999), and Gladiator (2000), incorporate backgrounds, action sequences, and even major characters conceived by illustrators and brought to life by technology. Such techniques are no less creations of the animator’s art than were Gertie, Betty Boop, and Bugs Bunny.

Additional Information

Computer animation is the process used for digitally generating moving images. The more general term computer-generated imagery (CGI) encompasses both still images and moving images, while computer animation only refers to moving images. Modern computer animation usually uses 3D computer graphics.

Computer animation is a digital successor to stop motion and traditional animation. Instead of a physical model or illustration, a digital equivalent is manipulated frame-by-frame. Also, computer-generated animations allow a single graphic artist to produce such content without using actors, expensive set pieces, or props. To create the illusion of movement, an image is displayed on the computer monitor and repeatedly replaced by a new similar image but advanced slightly in time (usually at a rate of 24, 25, or 30 frames/second). This technique is identical to how the illusion of movement is achieved with television and motion pictures.

To trick the visual system into seeing a smoothly moving object, the pictures should be drawn at around 12 frames per second or faster (a frame is one complete image). At rates below 12 frames per second, most people can detect jerkiness associated with the drawing of new images that detracts from the illusion of realistic movement. Conventional hand-drawn cartoon animation often uses 15 frames per second in order to save on the number of drawings needed, but this is usually accepted because of the stylized nature of cartoons. To produce more realistic imagery, computer animation demands higher frame rates.

Films seen in theaters in the United States run at 24 frames per second, which is sufficient to create the appearance of continuous movement.