Direct manipulation interface
Encyclopedia
In computer science
, direct manipulation is a human-computer interaction style which involves continuous representation of objects of interest, and rapid, reversible, incremental actions and feedback. The intention is to allow a user to directly manipulate objects presented to them, using actions that correspond at least loosely to the physical world. An example of direct-manipulation is resizing a graphical shape, such as a rectangle, by dragging its corners or edges with a mouse.
Having real-world metaphors for objects and actions can make it easier for a user to learn and use an interface (some might say that the interface is more natural or intuitive), and rapid, incremental feedback allows a user to make fewer errors and complete tasks in less time, because they can see the results of an action before completing the action, thus evaluating the output and compensating for mistakes.
The term was introduced by Ben Shneiderman
in 1983 within the context of office applications and the desktop metaphor. Individuals in academia and computer scientists doing research on future user interfaces often put as much or even more stress on tactile control and feedback, or sonic control and feedback than on the visual feedback given by most GUI
s. As a result the term direct manipulation interface has been more widespread in these environments.
GUI) as these almost always incorporate direct manipulation to at least some degree. However, direct manipulation should not be confused with these other terms, as it does not imply the use of windows or even graphical output. For example, direct manipulation concepts can be applied to interfaces for blind or vision-impaired users, using a combination of tactile and sonic devices and software.
It is also possible to design a WIMP interface that intentionally does not make use of direct manipulation. For example, most versions of windowing interfaces (e.g. Microsoft Windows
) allowed users to reposition a window by dragging it with the mouse, but would not continually redraw the complete window at intermediate positions during the drag. Instead, for example, a rectangular outline of the window might be drawn during the drag, with the complete window contents being redrawn only once the user had released the mouse button. This was necessary on older computers that lacked the memory and/or CPU power to quickly redraw data behind a window that was being dragged.
on the Atari ST
computer and first installed in restaurants in 1986 is an early example of an application specific GUI that manifests all of the characteristics of direct manipulation.
Mosher's POS touchscreen GUI has been widely copied and is in universal use on virtually all modern point of sale displays. Even in its earliest form it contained such features as 'lighting up' both selected 'buttons' (i.e., widgets) and 'tab' buttons which indicated the user's current position in the transaction as the user navigated among the application's pages.
In 1995 the ViewTouch GUI was developed into an X Window System
window manager, extending the usefulness of the direct manipulation interface to users equipped with no other equipment than networked displays relying on the X network display protocol. This application is a practical and useful example of the benefit of the direct manipulation interface. Users are freed from the requirement of making use of keyboards, mice and even local computers themselves while they are simultaneously empowered to work in collaborative fashion with each other in world wide virtual workgroups by merely interacting with the framework of graphical symbols on the networked touchscreen.
widgets are mostly standardized and are:
Depending on the specific common uses of an object, different kinds of widgets may be used. For example, a light in computer graphics is, like any other object, also defined by a transformation (translation and rotation), but it is sometimes positioned and directed simply with its endpoint positions because it may be more intuitive to define the position of the light source and then define the light's target, rather than rotating it around the coordinate axes in order to point it at a known position.
Other widgets may be unique for a particular tool, such as edge controls to change the cone of a spotlight, points and handles to define the position and tangent vector for a spline control point, circles of variable size to define a blur filter width or paintbrush size, IK
targets for hands and feet, or color wheels and swatches for quickly choosing colors. Complex widgets may even incorporate some techniques from scientific visualization
to efficiently present relevant data (such as vector fields for particle effects or false color images to display vertex maps).
Direct manipulation, as well as user interface design in general, for 3D computer graphics tasks, is still an active area of invention and innovation, as the process of generating CG images is generally not considered to be intuitive or easy in comparison to the difficulty of what the user wants to do, especially for complex tasks. The user interface for word processing, for example, is easy to learn for new users and is sufficient for most word processing tasks, so it is a mostly solved and standardized UI, while the user interfaces for 3D computer graphics are usually either difficult to learn and use and not sufficiently powerful for complex tasks, or sufficiently powerful but extremely difficult to learn and use, so direct manipulation and user interfaces will vary wildly from application to application.
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, direct manipulation is a human-computer interaction style which involves continuous representation of objects of interest, and rapid, reversible, incremental actions and feedback. The intention is to allow a user to directly manipulate objects presented to them, using actions that correspond at least loosely to the physical world. An example of direct-manipulation is resizing a graphical shape, such as a rectangle, by dragging its corners or edges with a mouse.
Having real-world metaphors for objects and actions can make it easier for a user to learn and use an interface (some might say that the interface is more natural or intuitive), and rapid, incremental feedback allows a user to make fewer errors and complete tasks in less time, because they can see the results of an action before completing the action, thus evaluating the output and compensating for mistakes.
The term was introduced by Ben Shneiderman
Ben Shneiderman
Ben Shneiderman is an American computer scientist, and professor for Computer Science at the Human-Computer Interaction Laboratory at the University of Maryland, College Park...
in 1983 within the context of office applications and the desktop metaphor. Individuals in academia and computer scientists doing research on future user interfaces often put as much or even more stress on tactile control and feedback, or sonic control and feedback than on the visual feedback given by most GUI
Gui
Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...
s. As a result the term direct manipulation interface has been more widespread in these environments.
In contrast to WIMP/GUI interfaces
Direct manipulation is closely associated with interfaces that use windows, icons, menus, and a pointing device (WIMPWIMP (computing)
In human–computer interaction, WIMP stands for "windows, icons, menus and pointers", denoting a style of interaction using these elements. It was coined by Merzouga Wilberts in 1980...
GUI) as these almost always incorporate direct manipulation to at least some degree. However, direct manipulation should not be confused with these other terms, as it does not imply the use of windows or even graphical output. For example, direct manipulation concepts can be applied to interfaces for blind or vision-impaired users, using a combination of tactile and sonic devices and software.
It is also possible to design a WIMP interface that intentionally does not make use of direct manipulation. For example, most versions of windowing interfaces (e.g. Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
) allowed users to reposition a window by dragging it with the mouse, but would not continually redraw the complete window at intermediate positions during the drag. Instead, for example, a rectangular outline of the window might be drawn during the drag, with the complete window contents being redrawn only once the user had released the mouse button. This was necessary on older computers that lacked the memory and/or CPU power to quickly redraw data behind a window that was being dragged.
In point of sale graphic interfaces
The ViewTouch graphic touchscreen POS (point of sale) GUI developed by Gene MosherEugene Mosher
Gene Mosher is best known for inventing the graphic touchscreen point of sale computer and is a pioneer of human-computer interaction, including touchscreen interfaces, application-specific GUIs, direct manipulation GUIs, widget toolkits, widget engines and network computing.Mosher is a 1966...
on the Atari ST
Atari ST
The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...
computer and first installed in restaurants in 1986 is an early example of an application specific GUI that manifests all of the characteristics of direct manipulation.
Mosher's POS touchscreen GUI has been widely copied and is in universal use on virtually all modern point of sale displays. Even in its earliest form it contained such features as 'lighting up' both selected 'buttons' (i.e., widgets) and 'tab' buttons which indicated the user's current position in the transaction as the user navigated among the application's pages.
In 1995 the ViewTouch GUI was developed into an X Window System
X Window System
The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...
window manager, extending the usefulness of the direct manipulation interface to users equipped with no other equipment than networked displays relying on the X network display protocol. This application is a practical and useful example of the benefit of the direct manipulation interface. Users are freed from the requirement of making use of keyboards, mice and even local computers themselves while they are simultaneously empowered to work in collaborative fashion with each other in world wide virtual workgroups by merely interacting with the framework of graphical symbols on the networked touchscreen.
In computer graphics
Because of the difficulty of visualizing and manipulating various aspects of computer graphics, including geometry creation and editing, animation, layout of objects and cameras, light placement, and other effects, direct manipulation is an extremely important part of 3D computer graphics. There are standard direct manipulation widgets as well as many unique widgets that are developed either as a better solution to an old problem or as a solution for a new and/or unique problem. The widgets attempt to allow the user to modify an object in any possible direction while also providing easy guides or constraints to allow the user to easily modify an object in the most common directions, while also attempting to be as intuitive as to the function of the widget as possible. The three most ubiquitous transformationTransformation (mathematics)
In mathematics, a transformation could be any function mapping a set X on to another set or on to itself. However, often the set X has some additional algebraic or geometric structure and the term "transformation" refers to a function from X to itself that preserves this structure.Examples include...
widgets are mostly standardized and are:
- the translationTranslation (geometry)In Euclidean geometry, a translation moves every point a constant distance in a specified direction. A translation can be described as a rigid motion, other rigid motions include rotations and reflections. A translation can also be interpreted as the addition of a constant vector to every point, or...
widget, which usually consists of three arrows aligned with the orthogonal axes centered on the object to be translated. Dragging the center of the widget translates the object directly underneath the mouse pointer in the plane parallel to the camera plane, while dragging any of the three arrows translates the object along the appropriate axis. The axes may be aligned with the world-space axes, the object-space axes, or some other space. - the rotationRotationA rotation is a circular movement of an object around a center of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...
widget, which usually consists of three circles aligned with the three orthogonal axes, and one circle aligned with the camera plane. Dragging any of the circles rotates the object around the appropriate axis, while dragging elsewhere will freely rotate the object (virtual trackball rotation). - the scaleScale (ratio)The scale ratio of some sort of model which represents an original proportionally is the ratio of a linear dimension of the model to the same dimension of the original. Examples include a 3-dimensional scale model of a building or the scale drawings of the elevations or plans of a building. In such...
widget, which usually consists of three short lines aligned with the orthogonal axes terminating in boxes, and one box in the center of the widget. Dragging any of the three axis-aligned boxes effects a non-uniform scale along solely that axis, while dragging the center box effects a uniform scale on all three axes at once.
Depending on the specific common uses of an object, different kinds of widgets may be used. For example, a light in computer graphics is, like any other object, also defined by a transformation (translation and rotation), but it is sometimes positioned and directed simply with its endpoint positions because it may be more intuitive to define the position of the light source and then define the light's target, rather than rotating it around the coordinate axes in order to point it at a known position.
Other widgets may be unique for a particular tool, such as edge controls to change the cone of a spotlight, points and handles to define the position and tangent vector for a spline control point, circles of variable size to define a blur filter width or paintbrush size, IK
Inverse kinematics
Inverse kinematics is a subdomain of kinematics, which is of particular interest in robotics and computer animation. In contrast to forward kinematics, which calculates the position of a body after a series of motions, inverse kinematics calculates the motions necessary to achieve a desired...
targets for hands and feet, or color wheels and swatches for quickly choosing colors. Complex widgets may even incorporate some techniques from scientific visualization
Scientific visualization
Scientific visualization is an interdisciplinary branch of science according to Friendly "primarily concerned with the visualization of three-dimensional phenomena , where the emphasis is on realistic renderings of volumes, surfaces, illumination sources, and so forth, perhaps...
to efficiently present relevant data (such as vector fields for particle effects or false color images to display vertex maps).
Direct manipulation, as well as user interface design in general, for 3D computer graphics tasks, is still an active area of invention and innovation, as the process of generating CG images is generally not considered to be intuitive or easy in comparison to the difficulty of what the user wants to do, especially for complex tasks. The user interface for word processing, for example, is easy to learn for new users and is sufficient for most word processing tasks, so it is a mostly solved and standardized UI, while the user interfaces for 3D computer graphics are usually either difficult to learn and use and not sufficiently powerful for complex tasks, or sufficiently powerful but extremely difficult to learn and use, so direct manipulation and user interfaces will vary wildly from application to application.