Forced perspective

“Forced perspective” is a technique that employs optical illusion to make an object appear farther away, closer, larger or smaller than it actually is. It is used primarily in photography, 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.

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.

Early instances of forced perspective used 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 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.
The 1930 Laurel and Hardy movie “Brats” used forced perspective to depict Stan and Ollie simultaneously as adults and as their own sons.

Peter Jackson’s film adaptations of “The Lord of the Rings” make extended use of 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 much smaller (for the dwarves and Hobbits) in relation to others.

Virtually all of the most bizarre and fascinating scenes in the movie “Eternal Sunshine of the Spotless mind” were created with old fashioned camera, editing, lighting and prop/set tricks. The use of digital effects was very limited. The striking kitchen scene with Joel as a child was created with an elaborate forced perspective set-up similar to some used by Peter Jackson in “The Lord of the Rings” trilogy.

Learn more about forced perspective at Wikipedia.

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