In the Phong shading model, the amount of light reflected from a surface has three components: the diffuse term D, the specular term S, and the ambient term A. By combining these terms the color of an object is given by: I = kd * D + ks * S + ka * A, where (kd, ks, ka) describe the reflection properties of the object.

Describe how the diffuse term D is calculated? What additional information about the object or the environment do we need? Use diagrams and equations to explain.

Describe how the specular term S is calculated? What additional information about the object or the environment do we need? Use diagrams and equations to explain.