• In dithering the dot patterns are made to be at 45 degree angles. This is because if the pattern were horizontal, or vertical, the human eye would detect the repeated pattern easily (this is also done with newspaper pictures).
• When light strikes a surface it is often reflected. The reflection model is quite simple. In this case a simple fraction of the incoming light will be used. More sophisticated models may be constructed using information about particular materials.
• When light enters or exits material, its path changes. There are also optical adjustments based on the transparency of the specific material. The path change is determined by Snell’s law, and the change in optical properties are considered by a simplified formula.
• After the collision vector has been calculated, the object’s transparency must be taken into account. This is done by using a transparency coefficient ‘t’. When ‘t’ has a value of 1 the object is opaque, and all light originates from the surface. If the object has a ‘t’ value of 0, then all light is from refraction.
• The highlights which often appear on an illuminated object can be estimated also. In this case the Phong model is used. This model includes an estimate of how ‘fuzzy’ the light patch appears. This is not done if the collision point lies in a shadow.