CS Information Visualization March 4, 2004 John Stasko

Transcription

1 WWW and Internet CS Information Visualization March 4, 2004 John Stasko Internet and WWW By nature, abstract, so good target for visualization Often described in terms of metaphors Information Superhighway Spring 2004 CS

2 Agenda Two main topics Presentations of the Internet and WWW Focus on topology and navigation, similar to the graph visualization work Visual aids for browsing and using the WWW and the Internet Assistive visualizations not focusing on presenting net structure and connectivity Spring 2004 CS Internet and WWW Topology Fundamentally, the Internet is a graph with some existing physical topology, though that is often not how we want to conceptualize it Might think of it as having a structure Our discussions from graph visualization are germane here Spring 2004 CS

3 The Problem Mukherjea & Foley Spring 2004 CS 7450 WWW 95 5 The Problem Websites simply are too big Huge graphs Layout is challenging Spring 2004 CS

4 Step Back Why would someone want to visualize the WWW? Spring 2004 CS Some Reasons Aid authors and webmasters with production and organization of content Assist Web surfers making sense of the information Help researchers understand the Web Spring 2004 CS

5 Depictions of the Web Great web site that presents many different conceptualizations of cyberspace Atlas of Cyberspace Let s take a few minutes to browse... Spring 2004 CS Mapping the Internet Bill Cheswick at ATT Interesting visualizations plus the data sets are available Spring 2004 CS

6 Internet Traffic Paths Spring 2004 CS Mbone Map Spring 2004 CS

7 Immersive Systems Spring 2004 CS View of Web Site s Pages Spring 2004 CS

8 Web Site Spring 2004 CS Web Site Visitations Spring 2004 CS

9 Task Analysis Potential web-related tasks How and when has info been accessed? Where do people enter and spend time? How do they move about? What paths aren t traversed? Where are they coming from? What has been added, changed, deleted? Do changes affect navigation patterns? Do we need to do a redesign? Spring 2004 CS Data Set Each server request is a data case Example variables IP Address/Client host Timestamp URL requested HTTP status (success, not found, ) Bytes delivered Referencing URL (HTTP-Referrer) User agent (browser and OS info)... Spring 2004 CS

10 One Approach Use existing InfoVis tool (Eureka, Spotfire, InfoZoom, etc.), load the data set, and analyze it Get all the strengths and weakness of the InfoVis tool for supporting particular analysis tasks Spring 2004 CS Web Ecology Problem: Most visualizations of the web fail to present the dynamically changing ecology of users and documents on the web What do we mean by ecology metaphor? Chi, et al CHI 98 Spring 2004 CS

11 Web Ecology By understanding set of relationships (ecology) among users and their information environment, and its change through time (evolution) individuals can better understand Web Content Layout of physical and topological space Usage through time Spring 2004 CS Existing Visualizations Despite useful functions, problems Difficulty visualizing large number of documents Considerable amount of screen real-estate used Only permits the visualization of a site at a particular point in time, very difficult to make comparisons across times No mechanisms provided that allow differences in usage to be identified Spring 2004 CS

12 Techniques Disk Tree Center-rooted tree that represents the hyperlink structure of a web site Time Tube Set of disk trees that organizes and visualizes the evolution of web sites Spring 2004 CS Task Application Visualizations designed to be useful for Local - Finding specific content Comparison - Comparing info at two places Global - Discovering a trend or pattern in the site Spring 2004 CS

13 Analysis Domain April 97 7,588 items across a 30-day period 889 new items Daily log kept of additions, modifications, and deletions of content Base data comes from link info, usage log from web servers Topological info from custom hyperlink database Spring 2004 CS Disk Trees Interested in shortest number of hops from one document to another Breadth-first traversal transforms the web graph into a tree by placing the node as close to the root node as possible After obtaining this tree we then visualize the structure using the Disk Tree technique Spring 2004 CS

14 Disk Tree Lines - tree links Line size & brightness - page access frequency Color - page lifecycle stage new: red continued: green deleted: yellow Spring 2004 CS Advantages Structure is compact, with pattern easily recognizable When viewed straight on or at slight angles, no occlusion problems, since entire layout is on a 2-D plane Unlike cone trees, this 2-D representation can utilize a third dimension for other information, such as time Circularity pleasing to the eye Spring 2004 CS

15 Time Tubes Time Tubes are multiple disk trees layered out along a spatial axis Advantages By using a spatial axis to represent time, we see information space-time in a single visualization Focus and Context Possibility for Animation Spring 2004 CS Time Tubes Spring 2004 CS

16 Key Point Pages there any time during the studied period are shown in all disk trees for period, even if they didn t exist yet Spring 2004 CS Real Use Time Tube answers following questions: What devolved into dead wood? When did it? Was there a correlation with the restructuring of the web? Product safety pages got darker and darker, indicating lower usage Doesn t tell why page is less popular, just raises a flag to explore page further Spring 2004 CS

17 Real Use What evolved into a popular page? When did it? Was there a correlation with the restructuring of the Web site? Redesign of site called attention to Fact Book page Became more popular and the corresponding Disk Trees become greener and greener in successive weeks Spring 2004 CS Real Use How was usage affected by items added over time? Press release issued for new family of products, shown as red links Usage in the third week jumped from 1 access to 871 accesses, this example helps us understand that this was probably a well received product line Spring 2004 CS

18 Real Use How was usage affected by items deleted over time? Change in removing direct link from home page to main driver page did not negatively affect the overall use of driver information Info stayed green indicating usage, but link from home page was black, showing not much traffic Spring 2004 CS E-Commerce Applications What if your focus is on understanding user access patterns for web sites selling products to consumers? What tasks are important? Spring 2004 CS

19 One Approach Blue Martini Software Aggregate web data and visualize simplified graph of user movements through web site Highlight places where people leave before purchasing... Brainerd & Becker InfoVis 01 Spring 2004 CS Different icons represent different kinds of pages Only show most-used pages Spring 2004 CS

20 E-Commerce mimics mall shopping :^) Gender differences in purchase paths at websites Spring 2004 CS Aiding WWW Browsing Can we utilize information visualization techniques to help people interact with the WWW and the Internet? Battle lost in hyperspace problem Help us know what s there Help us find things Spring 2004 CS

21 WebBook and Web Forager Personal computers viewed as knowledge processors before Spreadsheets and calculators Now viewed as knowledge sources, portals to vast information worlds Networking and WWW Card, Robertson and York CHI 96 Spring 2004 CS WWW Problems Pages are hard to find Users get lost, can t relocate pages Difficulty organizing things once found Difficulty doing knowledge processing on found thing Interacting with web is too slow to incorporate gracefully into other activities Spring 2004 CS

22 Information Foraging Theory From Ecological Biology Idea: user stalks certain types of information Users have tendency to interact repeatedly with small clusters of information (locality of reference) Information encountered at certain rate Users evolve to increase finding rate Sources evolve to be more attractive Spring 2004 CS Mechanisms Evolved 3 mechanisms in the evolution of the web on the server side Indexes - Lycos search Table of contents - Yahoo Home pages provided by users with big lists of related links Spring 2004 CS

23 Assisting People To provide insight must support sensemaking restructuring recoding Hotlists are one mechanism in this direction Spring 2004 CS Improvements WebBook and Web Forager try to do two things to foster information sensemaking Move away from a single web page, and group and manipulate related pages Move from a work environment containing a single element to a workspace in which the page is contained with multiple other entities, including Web Books Spring 2004 CS

24 WebBook Spring 2004 CS Features WebBook allows for the rapid interaction with object at a higher level of aggregation than pages 3D book representation, uses animation Can ruffle through pages, leave bookmarks Spring 2004 CS

25 Applications Hot List books Topic books Search reports Book books... Spring 2004 CS Web Forager Spring 2004 CS

26 Web Forager Application that embeds the WebBook and other objects in a hierarchical 3D information workspace Workspace is intended to create patches from the web where high density of relevant pages (grouped together in Web Books) can be combined with rapid access Spring 2004 CS Constituents Hierarchical Workspace - 3 levels Focus Place - full page shown, direct interaction Intermediate memory space - books or pages placed when they are in use but not immediate focus Tertiary space - Storage (bookcase) Video Spring 2004 CS

27 Discussion Strengths/Weaknesses Spring 2004 CS Data Mountain 3D document management system Prototype is an alternative to web browser bookmarks or favorites Could be used for any kind of document management Robertson, et al UIST 98 Spring 2004 CS

28 Make-Up 3D inclined plane in which thumbnails of web pages are placed to serve as favorites User is responsible for organization Uses smooth animation and audio to assist interaction Spring 2004 CS Spring 2004 CS 7450 Video 56

29 User Study Data Mountain versus IE4 Favorites Experienced IE4 users Stored 100 pages, then retrieved them DM fared about-as-well with title cue DM fared better for all other cues Spring 2004 CS Leveraging Human Capabilities Spatial memory: analogy with paper placed on a pile on your desk User is responsible for personal organization 3D perception: minimal cognitive load, good utilization of screen space Spring 2004 CS

30 Interaction Techniques Placing pages: confinement to inclined plane makes normal 2D drag-and-drop sufficient; no unfamiliar 3D navigation needed Continuous feedback: both audio and visual feedback are natural; minimized unexpected interactions/surprises Spring 2004 CS Limitations/Future Limits number of pages stored No explicit support for grouping Landmarks/contours as helpers Spring 2004 CS

31 Discussion Strengths/Weaknesses Could it be used elsewhere? Spring 2004 CS Upcoming Spring Break Woo-woo Text & documents (2 days) Reading Chapter 10 Salton et al Mid-project reports due March 25 Spring 2004 CS

32 References Spence and CMS texts All referred to papers and websites McNamara & Defnet and Craighill, Robeson & Sheridan F 99 slides Spring 2004 CS