• 13 November: One PNG file generated with one polygon extracted from dataset, requiring:

• • associating polygon <->demographic data
  • understanding the gd library well enough to generate a PNG with a transparent polygon

• • extracting polygons with the Shapefile C library
  • extracting the appropriate demographic data from the dataset with the Shapefile C library and the data files
  • associating polygon <->demographic data
  • understanding the gd library well enough to generate a PNG with a transparent polygon

• • extracting the appropriate demographic data from the dataset with the Shapefile C library and the data files
  • associating polygon <->demographic data

• • extracting polygons with the Shapefile C library

• 4 November: Proposal finished

• • understanding the gd library well enough to generate a PNG with a transparent polygon

• Set ALLOWTOPICCHANGE = DuckySherwood

• I am not a database whiz. I built a materials tracking system eighteen years ago using an RDBMS, but have basically not used databases since them.
• I have significant experience in a basket full of programming languages, including Smalltalk, perl, C++, C, Java, and a whiff of Python.
• I haven't ever written a Web server (that I can remember), but I have done a ton of CGI work and am very familiar with the HTTP protocol. I am very familiar with HTML, and have worked on a Web client.

Scenario

Webfoot's Information Visualization site

He clicks on the "Show population" checkbox below the map. The map changes to show the population: areas with fewer people have more of a yellow tinge; areas with more people have a bluer tinge. Areas with no residents -- industrial parks, water, recreational preserves, etc. -- have no tinge.

blah blah blah copyright and how-this-was-made information blah blah

Once Billy finds Rancho Cowabunga, he zooms in. When the polygons at one zoom level become too large to be interesting, they automatically deaggregate into smaller polygons.

At one point, he gets a little confused about what is on the map and what is part of the population overlay, so he unchecks the "Show population" box. The overlay vanishes, and his confusion is resolved.

Implementation approach

• 4 November: Proposal finished

• • killing small code gremlins
• 11 December: Performance tuning and bug fixes done, probably requiring finishing:

• • killing large code gremlins
• 16 December: Status update due, requiring
  • bibliography done
  • writing done
• 19 December: Final due date, requiring
  • learning LaTeX
  • coercing text into journal format
  • killing LaTeX gremlins

• Use a hierarchical database to allow faster aggregation of the census tracts.
• To improve performance, make the code memory resident with an HTTP server on it, instead of being connection-oriented.

Participants

Experience

• I have been very interested in a related visualization of census data for 20 years. I haven't ever gotten past the exploratory stages, but this means I am highly motivated to learn how to unravel US Census Bureau datasets.

• Roughly eighteen years of industrial experience makes me anticipate and plan for unanticipated problems.

What does this thing do?

Domain, task, and dataset

Also note that there will be areas with no people (e.g. big parks, the Stanford Industrial Park, commercial districts, the Bay, etc). I have left those clear.

How will I make it?

Proposed solution

I will show maps with the hue of polygons on the map representing the number of people living in that polygon as counted by the 2000 US Census. I will provide context to the users by making the polygons translucent, leaving the underlying map data discernible.

This project does not pretend to push the frontiers of research adequately to eject a publication. This project is designed to do something cool and useful.

I am more interested in providing (and more worried about) snappy performance than I am in broad geographical coverage. There are numerous opportunities for the performance to be inadequate. Determining the right data to display for a given clipping region, retrieving the information, aggregating information (when zoomed out), rendering the PNG image, and serving the image all take time (in addition to the time Google takes, which I won't be able to control).

I expect that I will need to trade disk space for speed, pre-processing information and caching some information on disk. As my last name isn't Google, I expect that I will not have enough disk space to handle all of the United States. I am willing to restrict the geographic range in order to ensure optimal performance. If I need to restrict the area of interest, my final paper will discuss what resources would be needed for the entire US.

Milestones

• 4 November: Proposal finished
• 13 November: One PNG file generated with one polygon extracted from dataset, requiring:
  • extracting polygons with the Shapefile C library
  • extracting the appropriate demographic data from the dataset with the Shapefile C library and the data files
  • associating polygon <->demographic data
  • understanding the gd library well enough to generate a PNG with a transparent polygon
• 20 November: Functional panning, perhaps limited to one US state and perhaps slow, requiring:
  • determining which polygons will be visible given lat/long bounds
  • iterating through visible polygons, drawing each
  • plugging overlays into the Google Maps API
• 4 December: Functional zooming
  • determining which polygons will be visible given lat/long bounds and zoom level
  • aggregating lower-level data (note that I do not think this is trivial)
• 11 December: Performance tuning and bug fixes done, possibly requiring:
  • pre-processing census bureau data into a form that is easier to extract quickly
  • prefetching of neighboring overlays
  • caching previously-used overlays
• 16 December: Status update due

Future work

• I believe that once I am able to display total population density, then it is relatively easy to extend the code to allow displaying one of many different flavors of demographic data, e.g. the non-white population. I would like to do that, think I can probably do it, but hesitate to promise it.
• Allowing the user to select information from one of several different censuses is also clearly within the realm of imagination. I believe that this is slightly too ambitious (in part due to disk space limitations) for the scope of the class.

Ducky's InfoVis Project Proposal

Participants

Description

Personal expertise:

Proposed solution

Scenario

Webfoot's Information Visualization site

Once he has zoomed in to the area he's interested in, he clicks the "Show population" checkbox. The map changes to have a translucent overlay over it. Areas with more people have more of a yellow tinge; areas with fewer people have a bluer tinge.

Billy uses the standard Google controls to move around, and the population overlay moves with the map. Billy is able to click-to-recenter, pan by dragging, pan by clicking on the directional controls, and zoom by clicking on the zoom controls. At every stage, the overlay pans and/or resizes to match the map.

Illustration

Implementation approach

Milestones

• 4 November: Proposal
• 16 December: Update due
• 19 December: Final due date

• Explore different color bars in hope of finding something better

• (aggressive) Allow user to choose from several different years of data

I might need to restrict the dataset to some subset of the United States because of resource limitations. I am not Google, and cannot store as much data as I suspect would be necessary to provide optimal performance.

There are all kinds of interesting and useful things that could be done on top of the base project.

• I believe that once I am able to display total population density, then it is relatively easy to extend the code to allow displaying one of many different flavors of demographic data, e.g. the non-white population. I would like to do that, think I can probably do it, but hesitate to promise it.
• Allowing the user to select information from one of several different censuses is also clearly within the realm of imagination. I believe that this is slighly more ambitious (in part due to disk space limitations), and probably not within the scope of the class.

• I did a project integrating maps, floorplans, and a virtual walkthrough about ten years ago at UIUC.

• I am not a graphics whiz. I am not sure what algorithms to use to select what data is likely to be visible. OTOH, I have Google and a copy of Foley and Van Dam within easy reach.

There are numerous opportunities for the performance to be inadequate. Determining the right data to display for a given clipping region, retrieving the information, aggregating information (when zoomed out), rendering the PNG image, and serving the image all take time (in addition to the time Google takes, which I won't be able to control). I expect that some caching and prefetching of data will be required.

Interface mock-ups

Implementation approach

• Figure out if Google Maps can overlay maps fast enough.

• Develop a simple test suite for PNG manipulation
• Write code to create PNG from one known polygon extracted from shapefile; overlay on Google Maps
• Write code to create PNG from several known polygons extracted from shapefile; overlay on Google Maps
• Write code to create PNG from several known polygons, shaded with data from dBASE file; overlay on Google Maps

• Given zoom level and map lat/long boundaries, figure out how to tell which polygons are visible
• Write code to retrieve a polygon based on lat/long.
• Write code to create PNG from lat/long boundaries at default zoom level
• Figure out how to aggregate data from multiple polygons
• Write code to aggregate data
• Modify code to create PNG from lat/long/zoom data

Note: I had worried that the overlaying might be too slow, but I have seen someone else overlay transpart Google Maps over Google satellite images with totally adequate performance.

• I am not a graphics whiz. I am not sure what algorithms to use to select what data is likely to be visible. OTOH, I have not only a copy of Foley and Van Dam, but also Google, within easy reach.

• Figure out how to overlay one png on static map
• Figure out how to overlay another png when map is recentered

• Find good shapefiles
• Create PNG overlay from one known polygon extracted from shapefile; overlay on Google Maps
• Create PNG overlay from several known polygons extracted from shapefile; overlay on Google Maps
• Create PNG overlay from several known polygons, shaded with data from dBASE file; overlay on Google Maps

• Given zoom level and map lat/long boundaries, determine which polygons are visible
• Create PNG overlay from zoom level and lat/long boundaries
• Overlay images dynamically on Google Maps

• (aggressive) Add sliders to allow changing the parameters of the image (e.g transparency, hue)
• (aggressive) Add radio buttons to change data sets

I plan to use C language Shapefile C library to parse a variant of the TIGER/Line data -- the ESRI shapefile data.

Ducky's InfoVis Project Proposal

Proposal specs

Participants

Description

Personal expertise:

• I did a project integrating maps, floorplans, and a virtual walkthrough years ago at UIUC.
• I have investigated several maps/census schemes in the past 10 years, but never gotten past the exploratory stages.
• I am sort of aware of
• I have never written anything in Javascript before, nor any dynamic client-side code of any kind, but would like to learn.
• This could be a really cool project.

Proposed solution

I will use Javascript and the Google Maps API to serve maps, capture pan/zoom events, and to overlay area data on top of the Google Maps.

I will use the gd library, probably with a perl wrapper, to generate a transparent PNG image to overlay on top of the maps.

I will use either @@@

• TIGER/Line shapefile information to determine the

Scenario

A scenario spells out what a user would have to do and what he or she would see step-by-step in performing a task using a given system. The key distinction between a scenario and a task is that a scenario is design-specific, in that it shows how a task would be performed if you adopt a particular design, while the task itself is design-independent: it's something the user wants to do regardless of what design is chosen.

@@@

Interface mock-ups

@@@ (ready two: one for the Vancouver desirable-living-places, one for STAR scores)

Implementation approach

@@@ GMaps API, javascript, gd

Milestones

@@@