Before the birth of Microsoft Kinect, few people were familiar with the technology of motion sensing. Similar devices have been invented and developed originally for monitoring aerial and undersea aggressors in wars. Then in the non-military cases, motion sensors are widely used in alarm systems, lighting systems and so on, which could detect if someone or something disrupts the waves throughout a room and trigger predefined events. Although radar sensors and modern infrared motion sensors are used more popularly in our life, we seldom notice their existence, and can hardly make use of these devices in our own applications.

But Kinect changed everything from the time it was launched in North America at the end of 2010. Different from most other user input controllers, Kinect enables users to interact with programs without really touching a mouse or a pad, but only through gestures. In a top-level view, a Kinect sensor is made up of an RGB camera, a depth sensor, an IR emitter, and a microphone array, which consists of several microphones for sound and voice recognition. A standard Kinect (for Windows) equipment is shown as follows:

The Kinect device

The Kinect drivers and software, which are either from Microsoft or from third-party companies, can even track and analyze advanced gestures and skeletons of multiple players. All these features make it possible to design brilliant and exciting applications with handsfree user inputs. And until now, Kinect had already brought a lot of games and software to an entirely new level. It is believed to be the bridge between the physical world we exist in and the virtual reality we create, and a completely new way of interacting with arts and a profitable business opportunity for individuals and companies.

In this book, we will try to make an interesting game with the popular Kinect technology for user inputs, with the major components explained gradually in each chapter. As Kinect captures the camera and depth images as video streams, we can also merge this view of our real-world environment with virtual elements, which is called Augmented Reality (AR). This enables users to feel as if they appear and live in a nonexistent world, or something unbelievable exists in the physical earth.

In this chapter, we will first introduce the installation of Kinect hardware and software on personal computers, and then consider a good enough idea compounded of Kinect and augmented reality elements, which will be explained in more detail and implemented in the following chapters.