The transforms considered so far are used to manipulate and position objects
within the world space. What we will consider next is how a virtual
camera or observer is positioned in world space, and the process of converting
world coordinates to camera coordinates. The procedure used generally
depends on the method employed to define the camera’s frame of reference
within the world space, which may involve the use of direction cosines, Euler
angles or quaternions. We will examine how each of these techniques could be
implemented.