An automated computer graphic process of converting 3D wire frame models to 2D images accentuating its 3D photo realistic effects or non-photo realistic outlook refers to the trending concept of 3D rendering in graphic designs. Considering the final stage of creating the actual 2D image or animation from the prepared scene, 3D rendering could be compared with the real life setup of either capturing an image or shooting a scene.
3D rendering process over the period of time has evolved dynamically and the rendering approach today ranges from noticeably non-realistic wire frame rendering through polygon-based technique to more advance rending systems such as Radiosity, Ray tracing or Scan line rendering. Engagement time for rendering process depends on the level of customisation and detailing and ranges from fractions of second to days per single image or frame; in fact rendering methods would be better classified in either photo-realistic rendering or real-time rendering.
Primarily real time rendering refer to rendering for the media which is interactive in nature like 3D games and simulations where the goal is to present as much details as the eyes can process in a fraction of second. Calculation for real time rendering in such cases is approximately at the rate of 20 to 120 frames per second. Industry standard practice for 3D rendering is 24 frames per second which is bare minimum for the human eye to see and successfully create the illusion of movement. Technological advancements in processing speed of systems and developments of advance rendering techniques & software are able to simulate such visual effects using features like lens flares, depth of field or motion blur. Non –real time rendering process primarily in non-interactive media such as feature films and video takes advantage of limited processing power and are rendered much slowly to generate images with higher quality.
The basic techniques applied in digital media and artistic works to obtain photo-realism are ray tracing and radiosity. Over the period of years there had been development of much sophisticated rendering techniques to simulate many naturally-occurring effects like interaction of light with various forms of matter for instance to simulate rain, smoke or fire rendering technique of particle systems is been used or surface scattering to simulate light reflection in the volumes of solid objects such as human skin.
Today archetypes of reflection also known as scattering and shading are used to describe the appearance of a surface. Modern 3D computer graphics rely heavily on a simplified reflection model called Phong reflection model. Reflection or scattering can be considered as the relationship between the incoming and outgoing illumination at a given point. Some of the widely used reflections rendering techniques today are Flat Shading, Texture mapping, Bump mapping, Phong shading, Gouraud shading and Cel shading.