Usability First » Computer Graphics

information visualization

jls — Wed, 30 Dec 2009 00:20:42 +0000

the study of how to effectively present information visually. Much of the work in this field focuses on creating innovative graphical displays for complicated datasets, such as census results, scientific data, and databases. An example problem would be deciding how to display the pages on a website or the files on a hard disk. Visualization techniques include selective hiding of data, layering data, taking advantage of 3-dimensional space, using scaling techniques to provide more space for more important information (e.g. fisheye views), and taking advantage of psychological principles of layout, such as proximity, alignment, and shared visual properties (e.g. color).

indication

jls — Tue, 29 Dec 2009 23:09:36 +0000

showing what item would be selected if the user were to click. Analogous to hiliting the current selection, indication highlights as the user mouses over items, helping the user to accurately make selections.

immersive interfaces

jls — Tue, 29 Dec 2009 23:01:47 +0000

an interface that heavily involves users by bringing them into the world of the interface both conceptually and perceptually, as in virtual reality, e.g. by surrounding their visual senses (as with VR glasses), giving them stereo sound, and providing an input technique which is as natural and automatic as possible.

icon

jls — Tue, 29 Dec 2009 22:44:08 +0000

in computer terminology (as opposed to graphic design terminology), an icon is a small image used most often to represent files or label a button. Much discussion goes into how icons should be designed: the use of line, color, and shading; how to effectively use symbols or representational images, and how to design families of icons.

hotspot

jls — Tue, 29 Dec 2009 21:24:32 +0000

the sensitive region of an image, such as the areas that are clickable on an imagemap displayed on a website, or the position on a pointer icon that indicates the exact point that is being pointed at.

head-mounted display

jls — Tue, 29 Dec 2009 18:41:16 +0000

HMD; a computer monitor or other display (such as an LED readout) that can be worn on the head so that a user can view it without looking away from the surrounding environment and without having to hold the display, while remaining portable. An HMD may display to both eyes, especially useful for immersive virtual reality systems, or to a single eye, useful for computer work aids or as personal assistants.

halo effect

jls — Tue, 29 Dec 2009 18:26:18 +0000

(graphics) the glow that appears around an antialiased image when it is placed over a background color that is different from the background used when making it antialiased. This occurs for gif images, which allow transparency, but only for an individual pixel to be either 100% transparent or not, not for instance, 50% transparent. Thus, when transparent, antialiased gif images need to be created, they need to be created on a background that is the same color or a near color to their final destination background color.

grid

jls — Mon, 28 Dec 2009 18:13:41 +0000

(graphic design) a system of templates used as a framework to create a document with uniform layouts between pages while still allowing each page to adapt to its content. The grid defines positions for standard elements on the page, margins, proportions, spacing, and edges along which elements will be aligned.

(computer graphics) in drawing software, a grid defines a series of visible or invisible, horizontal and vertical, uniformly-spaced edges for easy alignment of elements on a page. Autogrid features force all mouse input on the drawing surface to fall along those edges.

grab handles

jls — Mon, 28 Dec 2009 17:38:39 +0000

also called hotspot, birdie, or handle; small boxes on the edge of a selected object that can be grabbed and moved to drag or resize the object (or sometimes perform another manipulation, such as rotating the object).

gnomon

jls — Mon, 28 Dec 2009 17:05:22 +0000

a miniature view of the principal axes in a 3D coordinate system used to indicate the orientation of the current view in a 3D graphics system. (originally referred to the shadow of the pointer on a sundial)

interlacing

admin — Wed, 23 Dec 2009 23:33:31 +0000

displaying images by drawing only a partial image first, consisting of alternate lines, or every 3rd or 4th line, then filling in the remaining lines progressively. When images are displayed slowly, such as large gifs slowly downloading off the internet, this permits a useful preview of the image as it arrives. Interlacing is also used in the NTSC broadcast television standard to give the impression of a faster screen refresh rate — every 60th of a second, alternate lines (even or odd) are updated on the screen. Thus, the full screen is updated only every 30th of a second, but the impression is of faster refresh.

ghosting

jls — Wed, 23 Dec 2009 23:31:46 +0000

making an item fade when it is disabled (as when menu items are dimmed when they are currently unavailable); usually called dimming. An uncommon term, not to be confused with ghost indicators.

inverse video

admin — Wed, 23 Dec 2009 23:19:34 +0000

or reverse video; the use of inverted graphics (black for white and white for black) to indicated selected regions, usually used to refer to inverted text on alphanumeric terminals, but also inverted menu items and icons that are selected.

frame rate

jls — Wed, 23 Dec 2009 22:25:48 +0000

the speed that an animation or video is displayed, specifically: the number of frames (individual pictures making up the animation or video) that are displayed per unit time. For instance, televisions display 60 frames per second (also called the “refresh rate” when referring to televisions and computer monitors). Frame rate and resolution are two primary measures of video quality.

marquee

admin — Wed, 23 Dec 2009 21:27:37 +0000

1. (computer graphics) the dotted-line that appears around drawings when they are selected in drawing programs. When animated, a marquee is often referred to as the “marching ants”.

2. (graphic design) a hilited area, usually the focal point of a design, used to draw attention to particularly important information.

3. (website design) an HTML tag that produces text that automatically scrolls, almost always to be avoided because it is distracting and difficult to read.

follow through and overlapping action

jls — Wed, 23 Dec 2009 19:12:35 +0000

in animation, certain parts of an animation must keep moving even after the main action has completed, e.g. when a woman swings her head, her hair continues moving after she stops moving her head, and this hair motion may continue even as she begins her next action.

panning

admin — Wed, 23 Dec 2009 00:15:43 +0000

an alternative to scrolling for moving the viewed area within a window – the user drags the view (and usually the pointer changes to a flat hand) in 2 dimensions (instead of the 1-dimensional scrollbar).

In video, panning refers to moving the camera in a horizontal and vertical plane, but not along the depth axis.

exocentric viewpoint

jls — Wed, 23 Dec 2009 00:01:52 +0000

a virtual reality or immersive environment that is displayed around a person, for instance, by projecting scenes onto adjacent walls, rather than displaying it directly to someone’s senses (e.g. with a head-mounted display).

perspective wall

admin — Tue, 22 Dec 2009 23:51:44 +0000

a way of densely displaying large amounts of information by placing information on a flat plane which is tilted into the screen so that it shrinks back toward infinity. More important items (such as upcoming dates on a calendar) can be displayed at a closer location and thus appear larger than the less important items that are further away. This is one example of a general fisheye view approach.

raster display

admin — Tue, 22 Dec 2009 21:54:18 +0000

the standard technology for computer monitors that display images on a grid of pixels, allowing the computer to light up any individual pixel easily, and enabling color displays by having individual red, green, and blue (RGB) phosphors at each pixel point. In contrast to a vector display, raster displays can often require much more memory for a simple image and do not draw smooth diagonal lines, because all lines must be composed of a series of individual dots on a grid, creating an effect called aliasing.

resize handle

admin — Tue, 22 Dec 2009 21:09:43 +0000

a small box that appears at each of the corners of a selected object (and sometimes at the sides also) that can be dragged to alter the size of the object.

rollovers

admin — Tue, 22 Dec 2009 20:47:53 +0000

actions that occur as a user moves a pointer over objects, such as the hiliting of buttons as a user moves over them, in order to indicate that they are clickable, and also sometimes used to provide additional information (such as with tooltips or balloon help); frequently used on websites to help reinforce that graphics are clickable buttons.

egocentric viewpoint

jls — Tue, 22 Dec 2009 20:44:22 +0000

a virtual reality or immersive environment that is displayed into a person, by projecting it directly to a person’s senses with, for instance, a head-mounted display and headphones, as opposed to displaying the environment onto screens external to the person.

rubberbanding

admin — Tue, 22 Dec 2009 20:36:07 +0000

when creating or resizing graphics, such as a rectangle or oval, the way it stretches, like a rubberband, to follow the pointer as you drag it.

scientific visualization

admin — Tue, 22 Dec 2009 20:20:05 +0000

the graphical representation of complex physical phenomena in order to assist scientific investigation and to make inferences that aren’t apparent in numerical form. Typical examples include processing of satellite photographs and 3D representations of molecules and fluids to examine their dynamics.