Computer rendering Guide, Meaning , Facts, Information and Description
Rendering is the process of generating an image from a description of three dimensional objects, by means of a software program. The description is in a strictly defined language or data structure, and would contain geometry, viewpoint, texture and lighting information. The image is a digital image / raster graphics image.It is one of the major sub-topics of 3D computer graphics, and in practice always connected to the others. In the 'graphics pipeline' its the last major step, giving the final appearance to the models and animation. With the increasing sophistication of computer graphics since the 1970s onward, it has become a more distinct subject.
It has uses in: video editing/computer games, simulators, movies/tv special effects, and design visualisation. Each having a different balance of features and techniques.
As a product, a wide variety of renderers are available. some are integrated into larger modelling and animation packages, some are stand-alone, some are free open-source projects.
On the inside, a renderer is a carefully engineered program, based on a selective mixture of disciplines related to: light physics, visual perception, mathematics, and software development.
In the case of 3D graphics, rendering is a slow, computationally intensive process (typically for movie creation) or supported by realtime 3D hardware accelerators in graphic cards (typically for 3D computer games) or video editing cards. The term is by analogy with an "artist's rendering" of a scene.
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2 Features 3 Techniques 4 Academic Core 5 Chronology of published ideas 6 Books and summaries 7 External links |
Usage
When the pre-image (a wireframe sketch usually) is complete, rendering is used, which adds in Bitmap textures or Procedural textures, lights, bump mapping, and relative position to other objects. The result is a completed image the consumer or intended viewer sees.
For movie animations, several images (frames) must be rendered, and stitched together in a program capable of making an animation of this sort. Most 3-D image editing programs can do this.
For real-time, a complete calculation is not currently possible. Much faster is to simplify with one or both of these common approximations: No illumination, just texture mapping — since the intrinsic colors of an object has the greatest influence on its appearance. Or direct illumination — light from light-source to surface, then reflected from surface to camera/eye, since this light path is usually dominant in a scene. These would often be augmented with other special-case effects, or precalculations.
Features
A rendered image can be understood in terms of a number of visible features. Renderering research and development has been largely motivated by finding ways to simulate these efficiently. Some relate directly to particular algorithms and techniques, while others are produced together.Techniques
Two families of overall, light transport, techniques have emerged: radiosity - related to finite element mathematics, and ray tracing related to monte carlo mathematics. Both can provide a framework for a fairly complete solution to the rendering equation. Such approaches can be very slow and computationally-intensive.
The current state of the art in 3-D image description for movie creation is the RenderMan scene description language designed at Pixar. (compare with simpler 3D fileformats such as VRML or APIs such as OpenGL and DirectX tailored for 3D hardware accelerators).
Movie type rendering software includes:
- PRman
- BMRT (Blue Moon Rendering Tools)
- POV-ray
- Mental Ray
- Blender (which can also be used to produce a scene to be rendered)
Academic Core
Most rendering development and use aims at photorealism — to produce images indistinguishable from photographs.The implementation of a realistic renderer always has some basic element of physical simulation or emulation — some computation which resembles or abstracts a real physical process.
The term 'physically-based' indicates the use of physical models and approximations that are more general and widely accepted outside rendering. A particular set of related techniques have gradually become established in the rendering community.
The basic concepts are moderately straightforward, but intractable to calculate; and a single elegant algorithm or approach has been elusive for more general purpose renderers. In order to meet demands of robustness, accuracy, and practicality, an implementation will be a complex combination of different techniques.
Rendering research is concerned with both the adaptation of scientific models and their efficient application.
This is the key academic/theoretical concept in rendering. It serves as the most abstract formal expression of the non-perceptual aspect of rendering. All more complete algorithms can be seen as solutions to particular formulations of this equation.
Mathematics used in rendering includes: linear algebra, calculus, numerical mathematics, signal processing, monte carlo.
This is an Article on Computer rendering. Page Contains Information, Facts Details or Explanation Guide About Computer rendering the rendering equation
Meaning: at a particular position and direction, the outgoing light (Lo) is the sum of the emitted light (Le) and the reflected light. The reflected light being the sum of the incoming light (Li) from all directions, multiplied by the surface reflection and incoming angle.the BRDF
This is expresses a simple model of light interaction with a surface. Light interaction is often approximated by the even simpler models: diffuse reflection and specular reflection, although both can be BRDFs.geometric optics
the particle aspect of light physicsvisual perception
color scienceChronology of published ideas
Books and summaries
External links