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Overview

Choropleth Maps go to the Web Human-Computer Interaction Laboratory Department of Computer Science Ben Shneiderman, Kent Norman, Evan Golub, Haixia Zhao, Wayne Menezes. Overview. What is “Dynamap” ? Dynamap – Desire for Web-based solutions Dynamap – DHTML solution - layers and tables

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Overview

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  1. Choropleth Maps go to the Web Human-Computer Interaction Laboratory Department of Computer ScienceBen Shneiderman, Kent Norman, Evan Golub, Haixia Zhao, Wayne Menezes

  2. Overview • What is “Dynamap” ? • Dynamap – Desire for Web-based solutions • Dynamap – DHTML solution - layers and tables • Dynamap – Java solutions - single image w/palette manipulation - shape-based image construction

  3. Mention chloropleth, double-box sliders, zoom, pan, scatterplot What Is Dynamap • Motivation: • To provide a convenient, dynamic visual representation of summary data (example problem space - census data) • Typical applications • Exploratory Tasks, Specific Scenario Tasks • Technology originally used • Visual Basic 6.0, ESRI MapObjects 2.0 • Issues • Uses MapObjects 2.0, not web-based, performance with all 3180 counties not real-time

  4. Dynamap – Web Based Solutions • Motivation in moving to Web-based solutions: • Dynamap goes to Web with equal (or greater) functionality when compared to the Visual Basic implementation. • Example target minimum equipment: • Pentium II 400 Mhz • 56k Modem • 1024x768 screen resolution • Performance: • Smooth interactive filtering • Minimum network transfer and delay

  5. Dynamap – Dynamic HTML • Technology We Used • GIFs with transparent backgrounds • HTML tables with colored cells • Dynamic HTML (Cascading Style Sheets, JScript)

  6. Dynamap – Dynamic HTML Screenshot

  7. Dynamap – Dynamic HTML Screenshot

  8. Dynamap – Dynamic HTML • Technology We Used • GIFs with transparent backgrounds • HTML tables with colored cells • Dynamic HTML (Cascading Style Sheets, JScript) • Issues • current version only works in IE5+ due to browser conflicts on DHTML standards (short-term issue) • performance can decrease noticeably with large number of layers (i.e.: though it is possible to have as many as 5000 layers displayed in Internet Explorer, if there are more than around 150, response time becomes noticeable) • laborious to introduce chloropleth coloring (one-time cost)

  9. Dynamap – Java Solutions • Technology We Used in Solution 1 • Base map GIF with up to 124 (5*5*5 - 1) regions

  10. Dynamap – Java Solution 1 Screenshot

  11. Dynamap – Java Solutions • Technology We Used in Solution 1 • Base map GIF with up to 124 (5*5*5 - 1) regions • Issues with Solution 1 • Number of regions: for more regions, need to either use different base image type (e.g.: BMP) which would increase download time or use multiple base maps to increase number of regions which will increase image processing time

  12. Dynamap – Java Solutions • Technology We Used in Solution 1 • Base map GIF with up to 124 (5*5*5 - 1) regions • Issues with Solution 1 • Number of regions: for more regions, need to either use different base image type (e.g.: BMP) which would increase download time or use multiple base maps to increase number of regions which will increase image processing time • Technology We Used in Solution 2 • GeoTools open-source Java toolkit to construct image

  13. Dynamap – Java Solution 2 Screenshots

  14. Dynamap – Java Solution 2 Screenshots

  15. Dynamap – Java Solutions • Technology We Used in Solution 1 • Base map GIF with up to 124 (5*5*5 - 1) regions • Issues with Solution 1 • Number of regions: for more regions, need to either use different base image type (e.g.: BMP) which would increase download time or use multiple base maps to increase number of regions which will increase image processing time • Technology We Used in Solution 2 • GeoTools open-source Java toolkit to construct image • Issues with Solution 2 • Greater download time • Response time suffers with higher number of regions

  16. Conclusion • Dynamic queries with choropleth maps are an attractive, responsive way to present summary information • Dynamic queries can be implemented for the Web! • There are trade-offs… • Low bandwidth – might not want to have to load GeoTools or might want to reduce number of images to transfer • Slow processor – might not want to have high number of regions or might want to reduce number of sliders Human-Computer Interaction Laboratory www.cs.umd.edu/hcil/census

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