Interaction - positioning.pdf

Chp 2-4: HCI Concepts: Human, Computer, Interaction SWE234: Human Computer Interaction POSITIONING, POINTING AND DRAWING  mouse, touchpad trackballs, joysticks etc. touch screens, tablets eyegaze, cursors ©PRISCILLA OLAWALE (MSC) SPRING2024 2 the Mouse Han...

Chp 2-4: HCI Concepts: Human, Computer, Interaction SWE234: Human Computer Interaction POSITIONING, POINTING AND DRAWING  mouse, touchpad trackballs, joysticks etc. touch screens, tablets eyegaze, cursors ©PRISCILLA OLAWALE (MSC) SPRING2024 2 the Mouse Handheld pointing device ◦ very common ◦ easy to use Two characteristics ◦ planar movement ◦ buttons (usually from 1 to 3 buttons on top, used for making a selection, indicating an option, or to initiate drawing etc.) ©PRISCILLA OLAWALE (MSC) SPRING2024 3  the mouse (ctd) Mouse located on desktop ◦ requires physical space ◦ no arm fatigue Relative movement only is detectable. Movement of mouse moves screen cursor Screen cursor oriented in (x, y) plane, mouse movement in (x, z) plane … … an indirect manipulation device. ◦ device itself doesn’t obscure screen, is accurate and fast. ◦ hand-eye coordination problems for novice users ©PRISCILLA OLAWALE (MSC) SPRING2024 4 How does it work? Two methods for detecting motion Mechanical ◦ Ball on underside of mouse turns as mouse is moved ◦ Rotates orthogonal potentiometers ◦ Can be used on almost any flat surface Optical ◦ light emitting diode on underside of mouse ◦ may use special grid-like pad or just on desk ◦ less susceptible to dust and dirt ◦ detects fluctuating alterations in reflected light intensity to calculate relative motion in (x, z) plane ©PRISCILLA OLAWALE (MSC) SPRING2024 5 Even by foot … some experiments with the footmouse ◦ controlling mouse movement with feet … ◦ not very common :-) but foot controls are common elsewhere: ◦ car pedals ◦ sewing machine speed control ◦ organ and piano pedals ©PRISCILLA OLAWALE (MSC) SPRING2024 6 Touchpad small touch sensitive tablets ‘stroke’ to move mouse pointer used mainly in laptop computers good ‘acceleration’ settings important ◦ fast stroke ◦ lots of pixels per inch moved ◦ initial movement to the target ◦ slow stroke ◦ less pixels per inch ◦ for accurate positioning ©PRISCILLA OLAWALE (MSC) SPRING2024 7 Trackball and thumbwheels Trackball ◦ ball is rotated inside static housing ◦ like an upsdie down mouse! ◦ relative motion moves cursor ◦ indirect device, fairly accurate ◦ separate buttons for picking ◦ very fast for gaming ◦ used in some portable and notebook computers. Thumbwheels … ◦ for accurate CAD – two dials for X-Y cursor position ◦ for fast scrolling – single dial on mouse ©PRISCILLA OLAWALE (MSC) SPRING2024 8 Joystick and keyboard nipple Joystick ◦ indirect pressure of stick = velocity of movement ◦ buttons for selection on top or on front like a trigger ◦ often used for computer games aircraft controls and 3D navigation Keyboard nipple ◦ for laptop computers ◦ miniature joystick in the middle of the keyboard ©PRISCILLA OLAWALE (MSC) SPRING2024 9 Touch-sensitive screen Detect the presence of finger or stylus on the screen. ◦ works by interrupting matrix of light beams, capacitance changes or ultrasonic reflections ◦ direct pointing device Advantages: ◦ fast, and requires no specialised pointer ◦ good for menu selection ◦ suitable for use in hostile environment: clean and safe from damage. Disadvantages: ◦ finger can mark screen ◦ imprecise (finger is a fairly blunt instrument!) ◦ difficult to select small regions or perform accurate drawing ◦ lifting arm can be tiring ©PRISCILLA OLAWALE (MSC) SPRING2024 10 Stylus and light pen Stylus ◦ small pen-like pointer to draw directly on screen ◦ may use touch sensitive surface or magnetic detection ◦ used in PDA, tablets PCs and drawing tables Light Pen ◦ now rarely used ◦ uses light from screen to detect location BOTH … ◦ very direct and obvious to use ◦ but can obscure screen ©PRISCILLA OLAWALE (MSC) SPRING2024 11 Digitizing tablet Mouse like-device with cross hairs used on special surface - rather like stylus very accurate - used for digitizing maps ©PRISCILLA OLAWALE (MSC) SPRING2024 12 Eyegaze control interface by eye gaze direction ◦ e.g. look at a menu item to select it uses laser beam reflected off retina ◦ … a very low power laser! mainly used for evaluation (ch x) potential for hands-free control high accuracy requires headset cheaper and lower accuracy devices available sit under the screen like a small webcam ©PRISCILLA OLAWALE (MSC) SPRING2024 13 Cursor keys Four keys (up, down, left, right) on keyboard. Very, very cheap, but slow. Useful for not much more than basic motion for text-editing tasks. No standardised layout, but inverted “T”, most common ©PRISCILLA OLAWALE (MSC) SPRING2024 14 Discrete positioning controls in phones, TV controls etc. ◦ cursor pads or mini-joysticks ◦ discrete left-right, up-down ◦ mainly for menu selection ©PRISCILLA OLAWALE (MSC) SPRING2024 15