Definition of Direct Manipulation
An example of direct-manipulation is resizing a graphical shape, such as a rectangle, by dragging its corners or edges with a mouse.
Example 2: delete a file on your computer.
"Virtual Reality can be viewed as a field which can draw upon the principles of direct manipulation for Human-Computer Interaction (HCI) design or as an example or extension of direct manipulation itself. In VR, not only can task objects and actions be naturally represented, the task environment can be naturally represented as well. With either view, an understanding of direct manipulation principles is essential for the successful design of human computer interfaces in virtual environments."
"A favorite example to elucidate direct manipulation principles in contrast with the intermediary style of interaction (eg. traditional keyboard based, command driven interfaces), is travel in a car. With direct manipulation, you drive the car by manipulating the steering wheel and pedals. The car responds immediately to your actions, and these responses are immediately evident. If you are making a mistake such as turning too sharply, you can quickly recognize this and perform a corrective measure. With an intermediary style of interaction, you sit in the backseat of the car giving a stranger directions. Further, imagine the stranger possessing poor interpersonal skills and having a limited vocabulary. You've lost the feel for the road and you don't have a direct view of where you are going. Worse yet, you have to rely on a stranger who, if they don't receive explicit directions using particular phrases in a fixed order, idles in the middle of the road or takes you to unfamiliar places from which you don't know the way out."
"Because these benefits of direct manipulation are also desired in VR systems, direct manipulation principles should be drawn from when designing VR systems especially in the use of VR's special input devices. For instance, when using a data glove, a person should be able to select actions rapidly and easily by pointing and gesturing. Gestures should be natural and intuitive in the particular virtual environment. Actions should be represented visually and be incremental, immediate, and reversible to give a person the impression of acting directly in an environment."
Fundamental units of visual communication:
- Value (saturation/opacity)
Two types of retinal variables:
Scale of measurement for each variable:
- An associative variable does not affect the visibility of other dimensions (e.g. we can recognize color regardless of orientation.)
Hue, Orientation, Texture, Shape, Position are associative.
- A dissociative variable significantly affect the visibility of other dimensions (e.g. its hard to determine color of a thin line or small dot).
Size and Value are dissociative (they dominate perception and disrupt processing of other correlated dimensions)
- Categorical: Distinct categories should be obvious. For example, different states, jobs, or students.
Which variables can be used for categorical scale?
- Ordered: Determine relative ordering. For example, you rate your professor on the scale: good, medium, bad
Position, size, and value are ordered
- Quantitative: Determine amount of difference between
ordered values. For example, family income in US dollars.
Position and size are quantitative
Color brewer is a good resource for color selection: http://colorbrewer2.org/
This is the bar charts of the population of the USA over the last 8 years. The left chart shows how 3D hurts the visualization. The right chart is a less fancy but much more effective in 2D.
Pay attentions to the y-axis on the following charts of the same data.
Here is an example how visualization lies: from Time Magazine (4/9/79) via Tufte. Please avoid this.
These examples are charts from a recent version of Excel. 3D distorts the view making it more difficult (less accurate as well) to read the visualization.
A 2D version is much better. Picking up the right colors is also helpful: we could use colors to relate consoles. For example, Playstation 2 and Playstation 3 are both in (darker and lighter) blue.
Here is another bad example from Fox news:
Tables/images on this page are retrived from online resources. Some were adapted from Visualization and Visual Analytics class at UIC by Prof. Andrew Johnson.
© Last revised: Feb 7, 2018