CGI---Computer-generated image

There are lots of people who are fans of movies, especially those action films. One of the reason is for the special effects in those movies. The scene of wars and explosions, the transforming action in Transformers, and the grandiose scenes in Avatar. Those special effects used in films bring us the visual shock. In fact, those great special effects in films mostly are started by computer-programming, and a key technique is called CGI--Computer generated image.

CGI is one of the applications of computer graphics to create images in films, arts, TV programs,etc. Although CGI is mostly used in 3D graphics such as the special effects, it could still create 2D visual scenes. The term 'CGI animation' refers to dynamic CGI rendered as a movie. The term virtual world refers to agent-based, interactive environments. Computer graphics software is used to make computer-generated imagery for films, etc. Availability of CGI software and increased computer speeds have allowed individual artists and small companies to produce professional-grade films, games, and fine art from their home computers. This has brought about an Internet subculture with its own set of global celebrities, clichés, and technical vocabulary. The evolution of CGI led to the emergence of virtual cinematography in the 1990s where runs of the simulated camera are not constrained by the laws of physics.

Natural Landscapes and Architectural scenes are both typical representatives via CGI algorithms. In creating landscapes, the triangular mesh method is a very useful tool which relies on the construction of some special case of a de Rham curve, e.g.midpoint displacement. For instance, the algorithm may start with a large triangle, then recursively zoom in by dividing it into four smaller Sierpinski triangles, then interpolate the height of each point from its nearest neighbors. In the same way, architectural modelling tools also allow an architect to visualize a space and perform "walk-throughs" in an interactive manner, thus providing "interactive environments" both at the urban and building levels.

Undeniably, there are also other great representatives of CGI technique such as animations and computing interactions. In animation, in order to to create the illusion of movement, an image is displayed on the computer screen and repeatedly replaced by a new image which is similar to the previous image, but advanced slightly in the time domain. This technique is identical to how the illusion of movement is achieved with television and motion pictures. The computing interaction pays more attentions in "interactions" between users and characters ( Avatars).

Now we can feel the magic of CGI, which brings us into the "reality world" in virtual. 

Reference:

1. https://en.wikipedia.org/wiki/Special_effect#Introduction_of_computer_generated_imagery_.28CGI.29.

2. https://en.wikipedia.org/wiki/Computer-generated_imagery

Picture Reference:

1. https://en.wikipedia.org/wiki/Computer-generated_imagery#/media/File:FractalLandscape.jpg

2. https://www.google.com/search?q=transformers+special+effects&biw=1608&bih=849&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi6g-G5sZXPAhWFGz4KHT1KAU4Q_AUIBigB#imgrc=-cJTAp_p0bHlmM%3A

3. https://www.google.com/search?q=transformers+special+effects&biw=1608&bih=849&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi6g-G5sZXPAhWFGz4KHT1KAU4Q_AUIBigB#imgrc=Yx39R7KKD0IikM%3A