Interactive Input Methods & Graphical User Input.
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Transcript of Interactive Input Methods & Graphical User Input.
Interactive Input Methods & Graphical User Input
Explain the 6 logical classifications of input devices
Differentiate the 7 interactive Picture Construction Techniques
Types of input data: coordinate positions, attribute values, character-string specifications, geometric-transformation values, viewing conditions, illumination parameters,
Input procedures require interaction with display window managers & hardware devices.
Logical input device refers to input devices classified
according to data type. LOCATOR – specifies one coordinate position STROKE – specifies a set of coordinate
positions STRING – specifies text input VALUATOR – specifies a scalar value CHOICE – specifies menu selection PICK – specifies picture component selection
Devices like mouse, joystick,trackball, are used for screen-cursor position
General purpose keyboards may have 4 or 8 cursor-control keys
Light pen used for interactive input of coordinate position
graphic tablet & continuous movement of mouse, trackball, joystick are used to input a sequence of coordinate positions
primary physical device for string input is keyboard
other devices could generate character patterns that is recognized using stored dictionary of predefined patterns for specific application
valuator input is used to set scalar values for geometric transformations, viewing parameters & illumination parameters
panel of controls dials typically provides valuator input
display graphical representation of slider, buttons, rotating scales, menus
Joystick, trackball & keyboard could be adapted for valuator input by movement of the device relative to a scalar range
menus are used to select processing options, parameter values & object shapes
touch panel, keyboard & voice entry are also common choice devices
used to select part of a scene that is to be transformed or edited
using mouse, joystick or keyboard, picking the position of screen cursor to identify pixel coordinates
depending on type of object & complexity of scene, several levels of search required to identify pick object
variety of interactive methods are incorporated into graphic package as aids in construction of pictures:
1) Basic Positioning Methods interactively choose a coordinate position with
a pointing device that records the screen location
2) Dragging select an object & drag it to a new location,
thus object is then displayed in the new location.
3) Constraints procedure for altering input coordinate
values to obtain a particular orientation or alignment of an object
lines are constrained to have a particular slant
Input coordinates are constrained to lie along predefined paths
4) Grids rectangular grid displayed on screen area used
to round input coordinates to nearest grid intersection
grids facilitate object construction when need to joins new line to an existing line endpoint.
6) Rubber-Band Methods Line segments & other basic shapes constructed
& positioned using rubber-band methods to be interactively stretched or contracted
6) Gravity Field to connect lines at positions between endpoints
(that are not in grid intersections) graphic packages include procedure to convert any input position near a line segment into a position on the line using gravity field area around the line
any selected position within the gravity field of a line is “moved” to the nearest position on the line
7) Interactive Painting & Drawing Methods freehand drawing uses curves generated by
following the path of a stylus on a graphics tablet or path of the screen cursor on a video monitor
Applications include GUIs composed of display windows, icons, menus, etc to aid user in applying the software to a particular problem
consideration for user interface area: User Dialogue Windows & Icons Accommodating Multiple Skills Levels Consistency Minimizing Memorizing Backup & Error Handling Feedback