3D GLOSSARY

Normal (Surface Normal)
A three-dimensional vector which is perpendicular to a surface. Central to many computer graphics calculations.

Normal Mapping
An application of the technique known as bump mapping. While bump mapping perturbs the existing normal (the way the surface is facing) of a model, normal mapping replaces the normal entirely. Like bump mapping, it is used to add details to shading without using more polygons. But where a bump map is usually calculated based on a single-channel (interpreted as grayscale) image, the source for the normals in normal mapping is usually a multichannel image (with red/green/blue channels) derived from a set of more detailed versions of the objects.

Parallax mapping
Also Photonic Mapping, Offset Mapping or Virtual Displacement Mapping. It´s an enhancement of the bump mapping or normal mapping techniques applied to textures in 3D rendering applications such as video games. To the end user, this means that textures  will have more apparent depth and realism with less of an influence on the speed of the game. It works with a heightmap.

Photon mapping
A global illumination algorithm based on ray tracing used to realistically simulate the interaction of light with different objects. Specifically, it is capable of simulating the refraction of light through a transparent substance, such as glass or water, diffuse interreflections between illuminated objects, and some of the effects caused by particulate matter such as smoke or water vapor. It was developed by Henrik Wann Jensen.

Pixel Shader
A real-time shader application. A graphics processing function that calculates effects on a per-pixel basis. Pixel shaders are used to compute properties which, most of the time, are recognized as pixel colors.

Radiosity
A global illumination algorithm. A technique to calculate indirect light to illuminate a scene. It uses radiative transfer theory.

Ray tracing
a specific rendering algorithmic approach technique which follows rays from the eyepoint outward, rather than originating at the light sources. It produces results similar to ray casting  or scanline rendering, but facilitates more advanced optical effects, such as accurate simulations of reflections and refraction.