Per-pixel lighting
Encyclopedia
In computer graphics
, per-pixel lighting is commonly used to refer to a set of methods for computing illumination at each rendered pixel
of an image. These generally produce more realistic images than vertex lighting
, which only calculates illumination at each vertex of a 3D model and then interpolates
the resulting values to calculate the per-pixel color values.
Per-pixel lighting is commonly used with other computer graphics techniques to help improve render quality, including bump mapping
, specularity
, phong shading
, and shadow volume
s.
Real-time applications, such as computer games, which use modern graphics cards, will normally implement per-pixel lighting algorithms using pixel shaders. Per-pixel lighting is also performed on the CPU in many high-end commercial rendering applications which typically do not render at interactive framerates.
Computer graphics
Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....
, per-pixel lighting is commonly used to refer to a set of methods for computing illumination at each rendered pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
of an image. These generally produce more realistic images than vertex lighting
Gouraud shading
Gouraud shading, named after Henri Gouraud, is an interpolation method used in computer graphics to produce continuous shading of surfaces represented by polygon meshes...
, which only calculates illumination at each vertex of a 3D model and then interpolates
Interpolation
In the mathematical field of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points....
the resulting values to calculate the per-pixel color values.
Per-pixel lighting is commonly used with other computer graphics techniques to help improve render quality, including bump mapping
Bump mapping
Bump mapping is a technique in computer graphics for simulating bumps and wrinkles on the surface of an object. This is achieved by perturbing the surface normals of the object and using the perturbed normal during lighting calculations. The result is an apparently bumpy surface rather than a...
, specularity
Specularity
Specularity is the visual appearance of specular reflections. In computer graphics, it meansthe quantity used in 3D rendering which represents the amount of specular reflectivity a surface has...
, phong shading
Phong shading
Phong shading refers to an interpolation technique for surface shading in 3D computer graphics. It is also called Phong interpolation or normal-vector interpolation shading. Specifically, it interpolates surface normals across rasterized polygons and computes pixel colors based on the interpolated...
, and shadow volume
Shadow volume
Shadow volume is a technique used in 3D computer graphics to add shadows to a rendered scene. They were first proposed by Frank Crow in 1977 as the geometry describing the 3D shape of the region occluded from a light source...
s.
Real-time applications, such as computer games, which use modern graphics cards, will normally implement per-pixel lighting algorithms using pixel shaders. Per-pixel lighting is also performed on the CPU in many high-end commercial rendering applications which typically do not render at interactive framerates.
See also
- Phong shadingPhong shadingPhong shading refers to an interpolation technique for surface shading in 3D computer graphics. It is also called Phong interpolation or normal-vector interpolation shading. Specifically, it interpolates surface normals across rasterized polygons and computes pixel colors based on the interpolated...
- Stencil shadow volumes
- Unified lighting and shadowingUnified lighting and shadowingUnified shadow and lighting is the lighting model used in the Doom 3 game developed by id Software.Previous 3D games like Quake III Arena, used separate lighting models for determining how a light would illuminate a character or a map...