Designing Gestural Interfaces

THE MECHANICS OF TOUCHSCREENS AND GESTURAL CONTROLLERS

Even though forms of gestural devices can vary wildly—from massive touchscreens to invisible overlays onto environments—every device or environment that employs gestures to control it has at least three general parts: a sensor, a comparator, and an actuator. These three parts can be a single physical component, or, more typically, multiple components of any gestural system, such as a motion detector (a sensor), a computer (the comparator), and a motor (the actuator).

Figure 1-14. The basic components of any gestural system

A sensor is typically an electrical or electronic component whose job is to detect changes in the environment. These changes can be any number of things, depending on the type of sensor, of which there are many.^[11] The most common types currently used for interactive gestures are:

Pressure

To detect whether something is being pressed or stood on. This is often mechanical in nature.

Light

To detect the presence of light sources (also called a photodetector). This is used mostly in environments, especially in lighting systems.

Proximity

To detect the presence of an object in space. This can be done in any number of ways, from infrared sensors to motion and acoustic sensors.

Acoustic

To detect the presence of sound. Typically, this is done with small microphones.

Tilt

To detect angle, slope, and elevation. Tilt sensors generate ...