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Motion control photography is a special effects technique used in film that creates the illusion of size from small models by moving a small camera by the model at very slow speeds. It was first widely used in Star Wars which led to that movie's groundbreaking visuals, and has since become a standard technique for almost all films.
Modelmaking for scenery has long been used in the film industry, but when a model is too small it often loses its illusion and becomes "obviously a model". Solving this by building a larger model introduces a catch-22, larger models are much more difficult or fragile to move smoothly. Another solution is to move the camera instead of the model. This is not so easy, cameras are very large and heavy devices, and moving them is often as difficult as moving a large model.
This problem can be avoided to some degree by running the film at higher speeds, moving everything quickly, and then slowing everything down again. This results in much smoother motion that helps fool the eye. While this technique works well, it is very expensive to set up and shoot, and requires special cameras.
The real solution was to "fix" the camera, allowing it, or the model, to be moved much more accurately. The first suggestions that this was possible came about when John Whitney pioneered several motion techniques using old anti-aircraft analog computers connected to servos to control the motion of lights and lit targets.
Reversing the system, replacing the targets with a small camera, created the first motion control rigs. The camera could now be moved very finely and smoothly past a model of any size, and the illusion was far more convincing.
The downside to motion control is that it requires considerable programming in order to make the camera move the way you want. This was a real problem in the 1970s when the technique was first being developed, but by the 1990s the increasing power and "ease of use" of computers had made this a non-issue. The simultaneous increase in power and affordability of computer-generated imagery, however, has made the use of motion control photography less common.
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