Dynamic Visualization Dynamic Queries For Visual Information Seeking by Ben Shneiderman Data Visualization Sliders by Stephen G. Eick Presented by Yimeng Dou

Overview  Dynamic Queries Applies the principles of direct manipulation to the database environment  Data Visualization Sliders

Dynamic Query Approach  Visual presentation of the query’s components  Visual presentation of results  Rapid, incremental and reversible control  Immediate and continuous feedback  No need to learn a specific query language to use dynamic query. … rapid, animated, visual display of search results

Example 1: HomeFinder System

HomeFinder  Christopher Williamson's HomeFinder showed a map of Washington, DC and 1100 points of light indicating homes for sale.  Users could mark the workplace for both members of a couple and then adjust sliders to select circular areas of varying radii.  Other sliders selected number of bedrooms and cost, with buttons for air conditioning, garage, etc. Controlled experiments with benchmark tasks showed dramatic speed-ups in performance and high subjective satisfaction.

An Improvement To HomeFinder  ProgramFinder plots the available programs on a map of Maryland.  Adjusting the controls updates the display which shows a dot for each program that matches. A click on a program provides more details and the press of a button generates the paperwork.

Example 2: Cancer Rate  (Cervix cancer rates are color coded on the map. The year slider shows time trends. )  The other sliders allow interactive filtering of the gap according to the three chosen demographic parameters.

Example 3: Periodic Table  Periodic table with chemical symbols in red and six sliders for attributes such as atomic radius, ionization energy, and electronegativity.  As users move the sliders, the chemical symbols change to red showing the clusters, jumps, and gaps that chemists find fascinating.  A study with 18 chemistry students showed faster performance with use of a visual display (versus a simple textual list) and a visual input device (versus a form fillin box).

Example 3: Periodic Table

Example 4: Tabular Display  When there are no natural graphical displays for the output, dynamic queries can still be implemented with result sets shown in a traditional alphanumeric tabular display.  The sliders and buttons are created semi- automatically by the program depending on the values that exist in the imported ASCII database.  Display is updated only when the user releases the mouse button.

Tabular Display

Example 5: Dynamic Query of Unix Directory  Sliders for size (in kilobytes) and age (in days) of files enabled 18 users to answer ten questions such as "How many files are younger than umcp_tai?"  The three versions of the program are:  highlighting matches with color  highlighting matches with asterisks  displaying only the matching lines  In five of the tasks there was a statistically significant speed advantage for the Expand/contract interface.

Example 5: Dynamic Query of Unix Directory

Advantages  Visual presentation of query components  Visual presentation of results  Rapid, incremental and reversible actions  Selection by pointing (not typing)  Immediate and continuous feedback  For data in which there is a known relationship among variables, the dynamic queries interface is useful for training and education by exploration.  Where there is so much data, dynamic queries may help users to discover patterns, form and test hypotheses

Disadvantages  Requirement for rapid performance in search algorithms and display strategies cannot be easily satisfied with current database management tools.  Application specific programming is needed to take the best advantage of dynamic query methods.  Current dynamic queries implement only simple queries that are conjunctions of disjunctions, plus range queries on numeric values.  Visually handicapped and blind users will have a more difficult time with these widgets and outputs …stem largely from their poor match with current hardware and software systems

Research Directions (1)-- Research Directions (1)--Database and display algorithms  For small database (main memory): array indexing, grid structures, quad trees and k-d trees.  Larger database (disk): R-trees, grid files, various B-trees.  Display algorithms which can update quickly. (Buckets adjusted to granularity of the slider)  Data compression methods  Screen management algorithms  Only repaint the area that is changed  Manipulation of the palette by color indexing can be effective for irregularly shaped regions

Research Directions (2)-- Research Directions (2)--User Interface Design  Use pictures and capitalize on the human visual system.  Appropriate coding of properties like size, position, shape and color, to reduce explicit selection.  Graphical display properties such as color  Auditory properties.  No natural two-dimensional representation of the data is in currently available widgets.

Needed: New Widgets  Existing widgets are poorly matched with the needs of expert users. One possible solution: two dimensional input widgets. (Only one selecting is required to set two values, correct selections can be guaranteed).  Three and higher dimensional input widget may facilitate the exploration of complex relationships. One possibility: 3-D Mouse.  Ways of specifying alphanumeric fields. One possible solution: alphaslider.  How to specify complex boolean combinations of attributes. Example: filter/flow model.

Filter/Flow model  Users can select from the set of attributes and get an appropriate filter widget  (type-in for interest areas, sliders for cost, and buttons for scholarships)  The widget is placed on the screen with flow lines showing ANDs (sequential flow) and ORs (parallel flows).

Summary  The challenge now is to broaden the spectrum of applications by  improved user interface design  fast database search  compression methods  It can become a general approach attached to every database system, spreadsheet, etc.  Research directions include:  (1) database and display algorithms  (2) user interface design.

Data Visualization Sliders  Sliders provide a threshold bar within a scale that user can manipulate with a mouse to select a value.  The effectiveness of sliders may be increased by using the space inside the sliders as  An interactive color scale  A barplot for discrete data  A density plot for continuous data

Sliders in Information Visualization  Double-edged slider with upper and lower thresholds on network maps.  Categorical slider on software display for selecting an arbitrary subset. (see next slide for an example)  Ahlberg and Shneiderman’s FilmFinder uses a suite of double-edged sliders.

Seesoft (Example of categorical slider) Lines corresponding to service-affecting messages ( asserts, audits, peripheral interrupts, and prms ) are shown using different colors (gray levels).

Filtering  It’s the idea underlying these applications.  Sliders are used to restrict the information portrayed on the screen, thereby pruning the visual clutter and enabling the analyst to see important underlying patterns.

Example: Frost

Improvements Upon Traditional Sliders  The space inside the slider is used as a color scale, thereby efficiently utilizing screen real estate.  The data values are shown as tick marks in a “rug plot” in versions A and B and as the bar lengths in version D.  The distribution of the data is shown as a density plot in version B and as the bar lengths in version D.  Selected or turned-on, regions are shown in colors and unselected or turned-off regions are in dark gray. (Similar to operating a paint program)

Summary Of Important Ideas  Enabling a user to specify an arbitrary number of disconnected intervals while preserving the intuitive slider interface.  Using the space inside the slider as a color scale.  Interactively rebinding the colors either to the active bars or adjusting the color divisions.  Presenting the distribution of the data.  Showing individual data values, either as tick marks or as bar lengths.  Moving between the representations under user control, enabling the users to explore from several perspectives.  Linking sliders to the data they control suggests many natural and obvious extensions.