Graphics Term Overview

Rendering

Polygonal Modelling
a vertex is a point in 3D space with a particular location, usually given in terms of its x, y, and z coordinates. The basic object used in mesh modeling is a vertex, a point in three dimensional space. Two vertices connected by a straight line become an edge. Three vertices, connected to the each other by three edges, define a triangle, which is the simplest polygon in Euclidean space. More complex polygons can be created out of multiple triangles, or as a single object with more than 3 vertices. Four sided polygons (generally referred to as quads) and triangles are the most common shapes used in polygonal modeling. A group of polygons, connected to each other by shared vertices, is generally referred to as an element. Each of the polygons making up an element is called a face

Rendering
Rendering is the process of generating an image from a model, by means of a software program.

Aliasing
In statistics, signal processing, and related disciplines, aliasing is an effect that causes different continuous signals to become indistinguishable (or aliases of one another) when sampled. When this happens, the original signal cannot be uniquely reconstructed from the sampled signal. Aliasing can take place either in time, temporal aliasing, or in space, spatial aliasing.

Back-face Culling
In computer graphics, back-face culling determines whether a polygon of a graphical object, within the field of view of the camera, is visible. It is a step in the graphical pipeline that uses the test

Ax+By+Cz+D < 0

to test if the polygon is visible or not. If this test is true, the normal vector of the polygon is pointed away from the camera, meaning that the polygon is facing away and does not need to be drawn.

Clipping
In rendering, clipping refers to an optimization where the computer only draws things that might be visible to the viewer.

Photometry Vocabulary
Photometry is the science of measurement of light, in terms of its apparent brightness to the human eye. It is distinct from radiometry, which is the science of measurement of light in terms of absolute power.
 * Luminous intensity:Luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.
 * Luminous flux:power of emitted light (lumen). The SI unit of luminous flux is the lumen (lm). One lumen is defined as the luminous flux of light produced by a light source that emits one candela of luminous intensity over a solid angle of one steradian.
 * Illumination: incident light on a surface (lumen / m^2)
 * Attenuation: reduction in intensity (e.g. over a distance)

- see also Wikipedia:Photometry category

Flat Shading
Flat shading is lighting technique used in 3D computer graphics. It shades each polygon of an object based on the angle between the polygon's surface normal and the direction of the light source, their respective colors and the intensity of the light source.

Phong Shading
Phong shading is an interpolation method in 3D computer graphics, using interpolation of surface normals in rasterizing polygons, to get better resolution of specular reflections such as those generated by the Phong reflection model

Specular Highlights
A specular highlight is the bright spot of light that appears on shiny objects when illuminated (for example, see image at right). Specular highlights are important in 3D computer graphics, as they provide a strong visual cue for the shape of an object and its location with respect to light sources in the scene.

Ray Tracing
Ray tracing is a general technique from geometrical optics of modelling the path taken by light by following rays of light as they interact with optical surfaces.

Global Illumination
Global illumination algorithms used in 3D computer graphics are those which, when determining the light falling on a surface, take into account not only the light which has taken a path directly from a light source (direct illumination), but also light which has undergone reflection from other surfaces in the world (indirect illumination).

Radiosity
Radiosity is a global illumination algorithm used in 3D computer graphics rendering. Unlike direct illumination algorithms (such as ray tracing), which tend to simulate light reflecting only once off each surface, global illumination algorithms such as Radiosity simulate the many reflections of light around a scene, generally resulting in softer, more natural shadows.

High Dynamic Range Imaging (HDRI)
In computer graphics and cinematography, high dynamic range imaging (HDRI for short) is a set of techniques that allow a far greater dynamic range of exposures than normal digital imaging techniques. The intention is to accurately represent the wide range of intensity levels found in real scenes, ranging from direct sunlight to the deepest shadows.

High Dynamic Range Rendering (HDRR)
High dynamic range rendering (HDRR or HDR Rendering) or less commonly, high dynamic range lighting (HDR Lighting), is the rendering of 3D computer graphics scenes by using lighting calculations done in a high dynamic range. Specifically it refers to the new lighting model used to illuminate 3D worlds