Computer graphics lighting
Graphics artists can choose from a variety of light sources, models, shading techniques, and effects to suit the needs of each application.
[6] The intensity of ambient light is independent of direction, distance, and other objects, meaning the effect is completely uniform throughout the scene.
Games such as Team Fortress 2 use the rendering technique to create a cartoon cel shaded stylized look.
[11] The three primary lighting components (and subsequent interaction types) are diffuse, ambient, and specular.
[16] Currently, researchers are developing global illumination techniques to more accurately replicate how light interacts with its environment.
[17] This technique is fast to compute, but often is an incomplete approximation of how light would behave in the scene in reality.
[17] It is often approximated by summing a combination of specular, diffuse, and ambient light of a specific object.
[17] With this, the designer can decide how wide a highlight they want on an object; because of this, the power is called the shininess value.
[22] Light sources emit rays that interact with various surfaces through absorption, reflection, or refraction.
[23] It is possible to simulate this by having all of the light sources emit rays and then compute how each of them interact with all of the objects in the scene.
[26] Photon mapping was created as a two-pass global illumination algorithm that is more efficient than ray tracing.
[28] It is the basic principle of tracking photons released from a light source through a series of stages.
[29] In this process, the photon map is decoupled from the geometry of the scene, meaning rendering can be calculated separately.
[22] It is a useful technique because it can simulate caustics, and pre-processing steps do not need to be repeated if the view or objects change.
[29] Polygonal shading is part of the rasterization process where 3D models are drawn as 2D pixel images.
[30] This information includes vertex positional values and surface normals, but can contain optional data, such as texture and bump maps.
[2] Finally, the shading inside of the polygon is calculated as an interpolation of the surrounding edge values.
[2] Gouraud shading generates a smooth lighting effect across the 3D model's surface.
[34] The latter is more complicated and requires backwards ray tracing to simulate photons moving through the environment of the 3D render.
[33] In a photon mapping illumination model, Monte Carlo sampling is used in conjunction with the ray tracing to compute the intensity of light caused by the caustics.
[37] Over time, these particles may move, change color, or vary other properties, depending on the effect.
