Over the years, many films have stretched contemporary limits and enthralled audiences by producing mesmerising visuals. One could perceive a noticeable push towards special effects with the advent of computer-generated imaging (CGI).

The history of special effects goes back a long way, but CGI is relatively new. Computers were cumbersome things in the early 1970s, and an entire mainframe working for months could produce a few minutes of computer graphics. Graphics imaging in those days was primarily based on vector manipulation and involved huge chunks of code.

The entertainment world underwent a major change in the 1980s when images in Tron, Star Trek II, The Last Starfighter, and Young Sherlock Holmes gave the audience a taste of the future. The Abyss (1989) and the T-1000 in Terminator 2: Judgment Day (1990). In 1993, ILM smashed all previous conceptions about computer graphics when the photo-realistic dinosaurs in Jurassic Park took centre stage in theatres around the world.

What are the techniques that have made it possible for us to experience these dazzling effects?

Digital compositing
has been one of the most fruitful techniques to seamlessly composite hundred’s even thousand’s of scene elements to create some stunning sequences from elementary stuff shot on green screens. You can create a background (like the crowds in the car race scene in Phantom Menace), or surgically tailor two people (Forrest Gump), or create an entire environment. It is a method for combining two or more images. Ideally, the combined image looks exactly like the image that would have arisen from combining the scenes.

Morphing
In movie The Mask Morphing was used to manipulate his body into all kinds of contortions, mostly resembling cartoon animation.. Morphing is a technique used to transfer from one image to another. The idea is to make it appear as if one item is physically changing into the other. The animators select points which are similar on the two elements. For example eyes, ears, hair, and other such features work well for faces. This technique was also used in Michael Jackson’s music video Black or White and the Schwarzenegger thriller Terminator 2.

Motion capture
Another technique is motion capture, the creation of a 3D representation of a live performance. It is the process of capturing the movement of a real object and mapping it onto a computer generated object. Usually, Motion Capture is used to create synthetic actors by capturing the motions of real humans. In this case, special markers are placed over the joints of actors. Then, a special hardware samples the position and/or orientation of those markers in time, generating a set of motion data, also known as motion curves. This technique has been used by special effects companies to produce incredible realistic animations in movies such as Star Wars I, Titanic, Starship Troopers, Species, Batman, Terminator 2 and others

The sensor system that maps the live actor’s movement can be optical, electromagnetic, or even electromechanical in some cases. This technique has been heavely used in Sinbad: Beyond the Vale of Mists

Virtual camera movement is a cinematographic process that involves capturing the same image from different points simultaneously, but playing it back in sequence. One application of this process is a system of recording moving motion picture scenes that appear frozen in time. Similar but more advanced techniques were used in movie The Matrix
Technique which was used to create illusion of flying bicycle in ET, Leia or Luke flying at 100 mph on their speeder bike through the forest in Return of the Jedi is known as traveling matte or blue screen. This technique allows actors and scale models to find themselves in totally imaginary situations -- in space ships, dangling from rope bridges over gorges, flying through the air. If director wants to create the effect of actors walking across a large, flat plain while the sky boils with dark clouds, the cameraman can first shoot the actors on the plain. When this shot is created, the area of the sky is masked out. The scene is shot normally, but in the camera the film is exposed on only one half of the frame. Then, the camera operator rewinds the film in the camera, puts a piece of black paper on the lens to mask out the portion of the film already exposed, and films the clouds of a thunderstorm.

Today, anything is possible on screen. The success of Antz, Toy Story and A Bug’s Life has given way to a new genre of 3D animation movies. Mighty Joe Young, for example, had a computer generated gorilla that had its fur rippling in the breeze. Columbia Picture’s digital mouse Stuart Little has more than half a million digital hair that make up his head. Stuart’s clothes were digitally tailored not only to fit, but to crinkle and bend naturally.