This page is based on this
Wikipedia article Text is available under the
CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.
Rendering or image synthesis is the automatic process of generating a photorealistic or non-photorealistic image from a 2D or 3D model by means of computer programs. Also, the results of displaying such a model can be called a render. A scene file contains objects in a strictly defined language or data structure; it would contain geometry, viewpoint, texture, lighting, and shading information as a description of the virtual scene. The data contained in the scene file is then passed to a rendering program to be processed and output to a digital image or raster graphics image file. The term "rendering" may be by analogy with an "artist's rendering" of a scene.
Shading refers to depicting depth perception in 3D models or illustrations by varying levels of darkness.
Ray casting is the use of ray–surface intersection tests to solve a variety of problems in computer graphics and computational geometry. The term was first used in computer graphics in a 1982 paper by Scott Roth to describe a method for rendering constructive solid geometry models.
In computer graphics, the rendering equation is an integral equation in which the equilibrium radiance leaving a point is given as the sum of emitted plus reflected radiance under a geometric optics approximation. It was simultaneously introduced into computer graphics by David Immel et al. and James Kajiya in 1986. The various realistic rendering techniques in computer graphics attempt to solve this equation.
In computer graphics, ambient occlusion is a shading and rendering technique used to calculate how exposed each point in a scene is to ambient lighting. For example, the interior of a tube is typically more occluded than the exposed outer surfaces, and the deeper you go inside the tube, the more occluded the lighting becomes. Ambient occlusion can be seen as an accessibility value that is calculated for each surface point. In scenes with open sky this is done by estimating the amount of visible sky for each point, while in indoor environments only objects within a certain radius are taken into account and the walls are assumed to be the origin of the ambient light. The result is a diffuse, non-directional shading effect that casts no clear shadows but that darkens enclosed and sheltered areas and can affect the rendered image's overall tone. It is often used as a post-processing effect.
Beam tracing is an algorithm to simulate wave propagation.
It was developed in the context of computer graphics to render 3D scenes,
but it has been also used in other similar areas such as acoustics and
electromagnetism simulations.
Path tracing is a computer graphics Monte Carlo method of rendering images of three-dimensional scenes such that the global illumination is faithful to reality. Fundamentally, the algorithm is integrating over all the illuminance arriving to a single point on the surface of an object. This illuminance is then reduced by a surface reflectance function (BRDF) to determine how much of it will go towards the viewpoint camera. This integration procedure is repeated for every pixel in the output image. When combined with physically accurate models of surfaces, accurate models of real light sources, and optically correct cameras, path tracing can produce still images that are indistinguishable from photographs.
In optics, a caustic or caustic network is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light. Therefore, in the adjacent image, the caustics can be the patches of light or their bright edges. These shapes often have cusp singularities.
3D rendering is the 3D computer graphics process of automatically converting 3D wire frame models into 2D images on a computer. 3D renders may include photorealistic effects or non-photorealistic rendering.
The definition of the BSDF is not well standardized. The term was probably introduced in 1980 by Bartell, Dereniak, and Wolfe. Most often it is used to name the general mathematical function which describes the way in which the light is scattered by a surface. However, in practice this phenomenon is usually split into the reflected and transmitted components, which are then treated separately as BRDF and BTDF.
Computer graphics lighting refers to the simulation of light in computer graphics. This simulation can either be extremely accurate, as is the case in an application like Radiance which attempts to track the energy flow of light interacting with materials using radiosity computational techniques. Alternatively, the simulation can simply be inspired by light physics, as is the case with non-photorealistic rendering. In both cases, a shading model is used to describe how surfaces respond to light. Between these two extremes, there are many different rendering approaches which can be employed to achieve almost any desired visual result.
Reflection in computer graphics is used to emulate reflective objects like mirrors and shiny surfaces.
3D computer graphics or three-dimensional computer graphics, are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images. Such images may be stored for viewing later or displayed in real-time.
In computer graphics, unbiased rendering refers to a rendering technique that does not introduce any systematic error, or bias, into the radiance approximation. Because of this, it is often used to generate the reference image to which other rendering techniques are compared. Mathematically speaking, the expected value of the unbiased estimator will always be the population mean, for any number of observations. Error found in an unbiased rendering will be due to variance, which manifests itself as high-frequency noise in the resultant image. Variance is reduced by
and standard deviation by
for
data points, meaning that four times as many data points are needed to halve the standard deviation of the error. This makes unbiased rendering techniques less attractive for realtime or interactive rate applications. Conversely, an image produced by an unbiased renderer that appears smooth and noiseless is probabilistically correct.
Computer graphics is a sub-field of Computer Science which studies methods for digitally synthesizing and manipulating visual content. Although the term often refers to the study of three-dimensional computer graphics, it also encompasses two-dimensional graphics and image processing.
Volumetric path tracing is a method for rendering images in computer graphics which was first introduced by Lafortune and Willems. This method enhances the rendering of the lighting in a scene by extending the path tracing method with the effect of light scattering. It is used for photorealistic effects of participating media like fire, explosions, smoke, clouds, fog or soft shadows.
