Use of 3D rendering for creating graphics

Computer animation is skillfully creating moving images with the help of computer. 3D computers graphics can be explained as graphics that use a three dimensional representation of geometric figures that is stored in the computer for the purpose of performing calculation and rendering 2D images.

3D Rendering can be defined as the process of producing an image based on three-dimensional data stored within a computer. Rendering can be defined as the process of converting a model into an image either by simulating light transport to get photorealistic images, or by applying some of style as in non photorealistic rendering. It is the final stage in the creation of actual 2D image or animation from the prepared scene. It is almost similar to taking a photo or filming the scene after the setup is finished in real life.

In realistic rendering there are two basic operations:
1 Transport – the amount of light that gets from one place to another
2 Scattering – the process of interaction of surfaces with light
With the use of 3D computer graphic software or a 3D graphics API this step is performed.  The method of changing the scene into an appropriate form for rendering also involves 3D projection allowing a 3D image to be viewed in two dimensions.

There have been many different and specialized rendering techniques developed. It has a variety of distinctly non realistic wireframe rendering through polygon based rendering to more superior methods like: ray tracing, scanline rendering, or radiostiy.
The process of rendering can take from seconds to days for a single image / frame. Commonly, various methods are better suitable for either photo-realistic rendering, or real-time rendering. The graphic workstation computers make use of 2 to 4 processors. Thus they are much more powerful than a personal or a home computer and are specialized for the rendering process.

As the time for rendering is unpredictable video game animators tend to use low resolution, low polygon count renders, such that the graphics can be rendered in real time on a home computer. In such situations photorealistic animation would be impossible.

Rendering used for interactive media like games and simulation is calculated and displayed in real time. The rate of rendering in real time is around 20 to 120 frames per second. The goal here in real time rendering is to show as much information possible as the eye can process in a 30th of a second or one frame (in a 30 frame per second animation). There has been a speedy increase in computer processing power which has allowed a progressively higher degree of realism even for real time rendering. This also includes techniques like HDR rendering.

Rendering when used for the non-interactive media like feature films and videos, are rendered much more slowly. To get a higher image quality, non real time rendering enable the leveraging of limited processing power. In case of complex scenes, the rendering time for individual frames can vary from a few seconds to several days. Usually, rendered frames are first stored on a hard disk then are transferred to other media such as motion picture film or optical disk. Later these frames are put on sequentially at high frame rates, typically 24, 24 or 30 frames per second in order to achieve the illusion of movement.

In the process of 3D rendering the number of reflection “light rays” can take as well as different other characteristics can be modified to achieve a desired visual effect. Renderman by Pixar is rendering software which is broadly used as the movie animation industry standard in competition with Mental Ray.