Light and Shadow

  • Thomas Driemeyer
Part of the mental ray® Handbooks book series (MENTALRAY, volume 1)


All scene examples in the preceding Surface Shading chapter defined light sources that illuminate objects in certain ways. A light source provides light whose effect is taken into account when illuminating surfaces or volumes. Two main kinds of illumination are distinguished:
  • local illumination

    is handled by material and volume shaders by computing the color of an illuminated surface or volume simply by considering the direction, strength, and color of incoming light and how it is reflected towards the viewer. Incoming light always comes directly from the light source (which can optionally be blocked by occluding objects, causing shadows). The examples in chapter 4.1 on page 46 demonstrate various kinds of local illumination.

  • global illumination

    complements local illumination by allowing material shaders to take into account indirect illumination from other lighted objects in the scene. It cannot be computed by directly adding up incoming light from light sources but requires a special preprocessing step that emits photons from light sources and follows them as they bounce around in the scene. This allows simulating natural effects that go far beyond local illumination. Global illumination is described in chapter 7.6 on page 173.


Spot Light Shadow Casting Occlude Object Point Light Global Illumination 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Springer-Verlag Wien 2000

Authors and Affiliations

  • Thomas Driemeyer
    • 1
  1. 1.mental imagesGesellschaft für Computerfilm und Maschinenintelligenz mbH & Co. KGBerlinGermany

Personalised recommendations