Editing Pointing device (section)

== Classification ==
To classify several pointing devices, a certain number of features can be considered. For example, the device's movement, controlling, positioning or resistance. The following points should provide an overview of the different classifications.<ref>{{cite journal | last=Zhai | first=Shumin | title=User performance in relation to 3D input device design | journal=ACM SIGGRAPH Computer Graphics | volume=32 | issue=4 | date=1998 | issn=0097-8930 | doi=10.1145/307710.307728 | pages=50–54| s2cid=2708601 }}</ref>

* '''direct vs. indirect input'''
In case of a direct-input pointing device, the on-screen pointer is at the same physical position as the pointing device (e.g., finger on a touch screen, stylus on a tablet computer). An indirect-input pointing device is not at the same physical position as the pointer but translates its movement onto the screen (e.g., computer mouse, joystick, stylus on a graphics tablet).

* '''absolute vs. relative movement'''
An absolute-movement input device (e.g., stylus, finger on touch screen) provides a consistent mapping between a point in the input space (location/state of the input device) and a point in the output space (position of pointer on screen). 
A relative-movement input device (e.g., mouse, joystick) maps displacement in the input space to displacement in the output state. It therefore controls the relative position of the cursor compared to its initial position.

*''' isotonic vs. [[Elasticity (physics)|elastic]] vs. [[Isometre|isometric]]'''
An isotonic pointing device is movable and measures its displacement (mouse, pen, human arm) whereas an isometric device is fixed and measures the force which acts on it (trackpoint, force-sensing touch screen). 
An elastic device increases its force resistance with displacement (joystick).

* '''position control vs. rate control''' 
A position-control input device (e.g., mouse, finger on touch screen) directly changes the absolute or relative position of the on-screen pointer.
A rate-control input device (e.g., trackpoint, joystick) changes the speed and direction of the movement of the on-screen pointer.

* '''[[Translation (geometry)#Translations in physics|translation]] vs. [[rotation]]'''
Another classification is the differentiation between whether the device is physically translated or rotated.

* '''[[Degrees of freedom (physics and chemistry)|degrees of freedom]]'''
Different pointing devices have different degrees of freedom (DOF). A computer mouse has two degrees of freedom, namely its movement on the x- and y-axis. However the [[Wiimote]] has 6 degrees of freedom: x-, y- and z-axis for movement as well as for rotation.

* '''possible states'''
As mentioned later in this article, pointing devices have different possible states. Examples for these states are ''out of range, tracking or dragging''.

'''Examples'''

* a computer mouse is an ''indirect'', ''relative'', ''isotonic'', ''position-control'', ''translational'' input device with two ''degrees of freedom'' (x, y position) and  two states (tracking, dragging).
* a touch screen is a ''direct'', ''absolute'', ''isometric'', ''position-control'' input device with two or more ''degrees of freedom'' (x, y position and optionally pressure) and two states (out of range, dragging).
* a joystick is an ''indirect'', ''relative'', ''elastic'', ''rate-control'', ''translational'' input device with two ''degrees of freedom'' (x, y angle)  and two states (tracked, dragging).
* a Wiimote is an ''indirect'', ''relative'', ''elastic'', ''rate-control'', ''translational'' input device with six ''degrees of freedom'' (x, y, z orientation and x, y, z position) and two or three states (tracking, dragging for orientation and position; out-of-range for position).