6.2.1 Ambient Light

Even if there is no light falling directly from some light source onto the object it will still be seen, since light is partially reflected or scattered by neighboring objects or even the air. This would by far be too time consuming to calculate directly by a raytracer so one simulates this ambient light by the following clause in the finish statement:

	ambient T

Which says that the fraction $T$ of the ambient light (by default of rgb color 1) will contribute to the color of the object. This light depends neither on the position of the object, nor the viewing angle, nor has ambient light a fixed position in space but it fills the whole space uniformly.

So the intensity it contributes to a point on the surface of an object with ambient value T is given by

$$I_a := T*C_a,$$

where $C_a$ is the color of the ambient light.