Pointing device - Wikipedia. This article is about computer pointing devices. For the measuring tool used to copy sculptures, see Pointing machine. A pointing device is an input interface (specifically a human interface device) that allows a user to input spatial (i. CAD systems and graphical user interfaces (GUI) allow the user to control and provide data to the computer using physical gestures by moving a hand- held mouse or similar device across the surface of the physical desktop and activating switches on the mouse. Movements of the pointing device are echoed on the screen by movements of the pointer (or cursor) and other visual changes. Common gestures are point and click and drag and drop. While the most common pointing device by far is the mouse, many more devices have been developed. The conventional roller- ball mouse uses a ball to create this action: the ball is in contact with two small shafts that are set at right angles to each other. As the ball moves these shafts rotate, and the rotation is measured by sensors within the mouse. The distance and direction information from the sensors is then transmitted to the computer, and the computer moves the graphical pointer on the screen by following the movements of the mouse. Another common mouse is the optical mouse. This device is very similar to the conventional mouse but uses visible or infrared light instead of a roller- ball to detect the changes in position. Tracker balls are commonly used on CAD workstations for ease of use, where there may be no desk space on which to use a mouse. Some are able to clip onto the side of the keyboard and have buttons with the same functionality as mouse buttons. Isometric joysticks are often cited as more difficult to use due to the lack of tactile feedback provided by an actual moving joystick. Table; Term Definition; Branch. A branch is a named pointer to a commit. Selecting a branch in Git terminology is called to checkout a branch. If you are working in a certain branch, the creation of a new commit. Pointing stick. It is usually found on laptops embedded between the G, H, and B keys. It operates by sensing the force applied by the user. It is also found on mice and some desktop keyboards. Finger tracking. Fingers are triangulated by technologies like stereo camera, time- of- flight and laser. Good examples of finger tracking pointing devices are LM3. LABS' Ubiq'window and Air. Strike. Based on touching a surface. The thumb usually controls the clicking via a two- way button on the top of the pen, or by tapping on the tablet's surface. A cursor (also called a puck) is similar to a mouse, except that it has a window with cross hairs for pinpoint placement, and it can have as many as 1. A pen (also called a stylus) looks like a simple ballpoint pen but uses an electronic head instead of ink. The tablet contains electronics that enable it to detect movement of the cursor or pen and translate the movements into digital signals that it sends to the computer. It is a stationary pointing device, commonly used on laptop computers. At least one physical button normally comes with the touchpad, but the user can also generate a mouse click by tapping on the pad. Check out more Mother Goose Club Nursery Rhymes on our channel. Watch our featured videos! Advanced features include pressure sensitivity and special gestures such as scrolling by moving one's finger along an edge. It uses a two- layer grid of electrodes to measure finger movement: one layer has vertical electrode strips that handle vertical movement, and the other layer has horizontal electrode strips to handle horizontal movements. Users interact with the device by physically pressing items shown on the screen, either with their fingers or some helping tool. Several technologies can be used to detect touch. Resistive and capacitive touchscreens have conductive materials embedded in the glass and detect the position of the touch by measuring changes in electric current. Infrared controllers project a grid of infrared beams inserted into the frame surrounding the monitor screen itself, and detect where an object intercepts the beams. Modern touchscreens could be used in conjunction with stylus pointing devices, while those powered by infrared do not require physical touch, but just recognize the movement of hand and fingers in some minimum range distance from the real screen. Touchscreens are becoming popular with the introduction of palmtop computers like those sold by the Palm, Inc. For example the device's movement, controlling, positioning or resistance. The following points should provide an overview of the different classifications. An elastic device increases its resistance with displacement (Joystick, trackpoint). In case of a direct pointing device, the pointer is at the the same physical position as the pointing device. Relative means that the input controls the relative position of the cursor (mouse). Buxton's Taxonomy. The sub- rows distinguish between mechanical intermediary (i. It was introduced by Bill Buxton and is rooted in the human motor/sensory system. Continious manul input devices are categorized. Sub- columns distinguish devices that use comparable motor control for their operation. The three states describe the manipulation of a user interface that are out of range, tracking and dragging. Not every pointing device can switch to all states. Subsequently an overview of the model is given. Simple 2- State Transaction: Tracking & Dragging. A mouse is moved without the button being pushed. This state can be called tracking, meaning the user just moves the mouse without further interacting with the system. If the mouse is pointed at an icon and the button is pressed while moving the mouse, a new state called dragging is entered. These states are shown in the image . State 0- 1 Transaction: Out of Range & Tracking. If a touch tablet, which is able to sense touch or no- touch, is used instead of a mouse, the state model looks different. More precisely this means that any movement of the finger off the display is out of range and has no effect on the system. Only when the finger touches the display, the state switches to tracking (Figure: . State 0- 1- 2 Transaction: Out of Range, Tracking & Dragging.
If a graphics tablet with a stylus is used, it is possible to sense all three states. When the stylus is lifted, it is out of range. When it is in range, the state switches to tracking and the pointer follows the stylus' movement. Performing extra pressure on the stylus initiates state 2 dragging (Figure: . State 2 Set: Splitting States. By using a multiple- button mouse or multiple clicks, State 2 can be split into a set of states, i. For example selecting an object with Button 1 switches to the state Drag Original whereas Button 2 switches to Drag Copy. The same goes for multiple clicks known from Windows: one click on an object selects an object, double- clicks open it (Figure: . This scientific law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target. In other words, this means for example, that the user needs more time to click on a small button which is distant to the cursor, than he needs to click a large button near the cursor. Thereby it is generally possible to predict the speed which is needed for a selective movement to a certain target. Mathematical Formulation. W can also be thought of as the allowed error tolerance in the final position, since the final point of the motion must fall within . For example, a hardware mouse moves in another speed or distance than the cursor on the screen. Even if these movements take place in two different spaces, the units for measurement have to be the same in order to be meaningful (e. The CD gain refers to the scale factor of these two movements: CDgain=VDisplay/VControl. However, a compromise has to be found: with high gains it is easier to approach a distant target, with low gains this takes longer. High gains hinder the selection of targets, whereas low gains facilitate this process. As the tip of the light pen makes contact with the screen, it sends a signal back to the computer containing the coordinates of the pixels at that point. It can be used to draw on the computer screen or make menu selections, and does not require a special touch screen because it can work with any CRT display. Light gun. Palm mouse . Pucks are typically used for tracing in CAD/CAM/CAE work, and are often accessories for larger graphics tablets. Eye tracking devices . Users can operate a gyroscopic mouse when they have no room for a regular mouse or must give commands while standing up. This input device needs no cleaning and can have many extra buttons, in fact, some laptops doubling as TVs come with gyroscopic mice that resemble, and double as, remotes with LCD screens built in. Steering wheel . Can be used in a variety of work settings, and is ergonomically designed to maintain healthy posture of hand, wrist, elbow, and shoulder joints. The Roller. Mouse is often cited as a . User performance in relation to 3. D input device design. ACM Siggraph Computer Graphics, 3. A Three- State Model of Graphical Input. Amsterdam: Elsevier Science Publishers B. V. Journal of Experimental Psychology. PMID 1. 31. 74. 71. Casiez, G., & Roussel, N. Methods and Tools to Characterize, Replicate and Compare Pointing Transfer Functions. Proceedings of the 2. Annual ACM Symposium on User Interface Software and Technology - UIST . Optimality in human motor performance: Ideal control of rapid aimed movements. Psychological Review , 9.
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