Game Development Reference
Figure 2.1. The Kinect sensor and its individual camera system components.
system that can be used to track and inspect the scene in front of them. We will
investigate each of these devices in more detail in the following sections.
We begin with the color camera, as this is probably the most familiar device for
most developers (and consumers in general for that matter). This camera func-
tions more or less the same as a traditional web cam does. Visible light from the
scene enters into the camera lens and eventually strikes a sensing element inside
of the camera. With a large array of sensing elements arranged in a rectangular
grid, the camera can determine the amount of visible light in the scene over a
predefined area at a particular moment in time. This general concept is used to
synthesize a camera image at regular time intervals, which ultimately produces
a video stream. The geometry involved in this process is depicted in Figure 2.2.
With this in mind, we can consider the geometric interpretations of the scene
that are used in such an imaging system. It is quite common to utilize a pinhole
Figure 2.2. The geometry of the Kinect color camera.