Forced perspective
From Wikipedia, the free encyclopedia
Forced perspective is a technique that employs optical illusion to make an object appear farther, closer, larger or smaller than it actually is. It is used primarily in filmmaking and architecture. It manipulates human visual perception through the use of scaled objects and the correlation between them and the vantage point of the spectator or camera.
Contents |
[edit] Forced perspective in filmmaking
Examples of forced perspective:
- Imagine a scene in an action/adventure movie in which dinosaurs are threatening the heroes. By placing a miniature model of a dinosaur close to the camera, the dinosaur may look monstrously tall to the viewer, even though it is just closer to the camera.
- Imagine another scene in which two characters are supposed to be interacting in the foreground of a vast cathedral. Instead of actually filming in a cathedral, the director mounts a large painting of a cathedral's interior in a studio and films the actors talking in front of the painting. This gives the effect on film that the characters are in the foreground of a large room, when in reality they are standing next to a flat surface.
Movies (especially B-movies) in the 1950s and 1960s produced on limited budgets sometimes feature forced perspective shots which are completed without the proper knowledge of the physics of light used in cinematography, so foreground models can appear blurred or incorrectly exposed.
Forced perspective can be made more believable when environmental conditions obscure the difference in perspective. For example, the final scene of the famous movie Casablanca takes place at an airport in the middle of a storm, although the entire scene was shot in a studio. This was accomplished by using a painted backdrop of an aircraft, which was "serviced" by little people standing next to the backdrop. A downpour (created in-studio) draws much of the viewer's attention away from the backdrop and extras, making the simulated perspective less noticeable.
The example below, taken from Andrei Tarkovsky's Nostalghia, is one notable instance.
The shot begins at left, a closeup of a man and his dog, with the small house in the distance. A continuous slow pullback ends at right, revealing the man, dog, and the entire farmhouse setting to be enclosed in the columned courtyard. The shot was accomplished by building the farmhouse setting in miniature, and placing it closely behind the man and dog, shooting with lenses chosen to make the house appear distant at first.
[edit] Role of light
Early instances of forced perspective use in low-budget motion pictures showed objects that were clearly different from their surroundings: often blurred or at a different light level. The principal cause of this was geometric. Light from a point source travels in a spherical wave, decreasing in intensity (or illuminance) as the inverse square of the distance travelled. This means that a light source must be four times as bright to produce the same illuminance at an object twice as far away. Thus to create the illusion of a distant object being at the same distance as a near object and scaled accordingly, much more light is required.
Opening the camera's iris lets more light into the camera, allowing both near and far objects to be seen at a more similar light level, but this has the secondary effect of decreasing depth of field. This makes either the near or the far objects appear blurry. By increasing the volume of light hitting the distant objects, the iris opening can be restricted and depth of field is increased, thus portraying both near and far objects as in focus, and if well scaled, existing in a similar lateral plane.
Since miniature models would need to be subjected to far greater lighting than the main focus of the camera, the area of action, it is important to ensure that these can withstand the significant amount of heat generated by the incandescent light sources typically used in film and TV production, as they may be prone to combustion.
[edit] Nodal point: forced perspective in motion
Peter Jackson's film adaptations of The Lord of the Rings employ an almost constant forced perspective. Characters apparently standing next to each other would be displaced by several feet in depth from the camera. This, in a still shot, makes some characters appear unnaturally small (for the dwarves and hobbits) in relation to others.
A new technique developed for The Fellowship of the Ring was an enhancement of this principle which could be used in moving shots. Portions of sets were mounted on movable platforms which would move precisely according to the movement of the camera, so that the optical illusion would be preserved at all times for the duration of the shot. The same techniques were used in the Harry Potter movies to make the character Hagrid look like a giant. Note that props around Harry and his friends are of normal size, while identical props placed around Hagrid are smaller.
The techniques developed centred around a nodal point axis, so the camera's panning axis was at the point between the lens and aperture ring where the light travelling through the camera met its axis. By comparison, the normal panning axis would be at the point at which light would strike the film (or CCD in a TV camera).
Peter Jackson enhanced this known effect by adding moving jigs to extend the pan to be effective outside the camera during motion, which is not possible to show in a still photograph.
The position of this nodal point can be different for every lens. However, on wide angle lenses it is often found between the midpoint of the lens and the aperture ring.
[edit] Digital effects
Another method is to film the actions of the "smaller" character on a set with normal-sized props, film the matching actions of the "large" character on an identical but smaller set, then combine the footage digitally. This is the most straightforward modern technique, and is most likely to be used with bluescreen filming in TV production due to its lower cost and quality requirements.
[edit] Comedic effects
As with many film genre and effects, forced perspective can be used to visual comedy effect. Typically, an object or character is portrayed in a scene, its size defined by its surroundings. A character then interacts with the object or character, in the process showing that the viewer has been fooled and there is forced perspective in use.
An example used for comic effect can be found in the slapstick comedy Top Secret! in a scene which appears to begin as a close up of a ringing phone with the characters in the distance. However when the character walks up to the phone (towards the camera) and picks it up it becomes apparent that the phone is extremely oversized instead of close to the perspective of the camera.
The same technique is also used in the Dennis Waterman sketch in the British sketch show Little Britain, In the television version, oversized props are used to make the caricatured Waterman look just three feet tall (or even smaller in some cases, such as a series two episode which he is in a design of a set, which is a shoebox and he is the equivalent size to the objects). In real life, Waterman is of average height.
[edit] Forced perspective in architecture
In architecture, a structure can be made to seem larger, taller, farther away or otherwise by adjusting the scale of objects in relation to the spectator, increasing or decreasing perceived depth.
For example, when forced perspective is used to make an object appear farther away, the following method can be used: By constantly decreasing the scale of objects from expectancy and convention toward the farthest point from the spectator, an illusion is created that the scale of said objects is small due to their distant location.
Forced perspective is extensively employed at theme parks and other such (postmodern) architecture such as found in Las Vegas, often to make structures seem larger than they are in reality where physically larger structures would not be feasible or desirable or to provide an optical illusion for entertainment value.
