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Map Evolution

January 15, 2009


Recently, we took on a nice little print mapping project for a few hotels located in downtown Madison, Wisconsin. The project involved making a one-sided, page-sized map showing hotel locations and the locations of a few points of interest in the area. The idea was that hotel guests could use the map to find their way around downtown as well as get a sense for where they were staying in relation to the university, interstates, airport, etc. The map was to be printed in grayscale, plus 3 spot colors (red, yellow, and blue).

Before starting out, we discussed the possibility of sharing the project with those interested in seeing all the stuff that goes into designing a map like this. The map design process is notoriously difficult to articulate and we’re keen on the idea of making pieces of it more transparent, where possible. One option was to screen capture the hotel map as it appeared in the production software at regular time intervals from blank page to finished product. So, here is a sequence of 116 images, originally captured at 10-minute intervals, compiled to show the evolution of the hotel map in just under 2 minutes. Clearly, not all maps are made in the same way, but this should expose some of the kinds of design decisions made in a relatively simple project like this.

Watch the larger version of Map Evolution (990 x 766px) — best for seeing change in map details.

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Election map follow-up

December 22, 2008

After posting our election map last month, we received a number of excellent comments and suggestions. It’s late, but I thought I’d finally post the couple of variations of the map that I’ve managed to find time to put together. The maps below do two things differently from the original:

  • Vary the brightness of counties by population density rather than total population. This was a frequent suggestion. I think it has a few of its own drawbacks too, but it looks pretty good.
  • Different color schemes. Just for fun, I’ve used the purple color scheme that has become common in recent elections. I also liked the suggestion in one comment to saturate colors by margin of victory, so I’ve done that too. In these, full blue would be total Obama domination (Obamanation? Obamadom?), full red would be the same for McCain, and gray is an even split.

No snazzy posters this time. Just a few map snapshots.

First, the original colors mapped by population density, as posted in the comments on the original post.
Election map, population density

The purple color scheme. First by total population:
Purple election map with county populations

And by population density:
Purple election map with county population densities

Margin of victory by total population:
Margin of victory election map with county populations

Margin of victory by population density:
Margin of victory election map with county population densities

Apologies for any trouble seeing the images. It’s tricky to find a brightness that will look right on every screen.

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The Best of Both Worlds: Semi-transparent choropleth maps in GeoCommons Maker!

December 8, 2008

When we were building GeoCommons Maker! one of the key map design challenges we faced involved producing semi-transparent choropleth maps. Choropleth maps are perhaps the most common type of thematic map and are regularly used to show data that is attached to enumeration unit boundaries, like states or counties. Ever seen a red state / blue state election map? This is a basic choropleth. There are a lot of more sophisticated ways that choropleths can be made to best represent a given data set, for example, by playing around with classification, categorization, choice of color scheme, etc., but we won’t get into those here.

I want to talk about color. Traditionally, choropleth maps are read by looking at the general pattern of unit colors and/or by matching the colors of specific map units to a legend. Other reference data is often removed from the map because it is either, 1) not necessary to communicate the map’s primary message or 2) makes communicating this message more difficult. It could be argued, for example, that other reference map information, like green parks, gray airports, brown building footprints, and blue water distract readers from seeing the general pattern of choropleth colors on the map, which is where the map’s most important message can be found.

For GeoCommons Maker!, we wanted to allow people to make a kind of hybrid, semi-transparent choropleth map that would show both thematic data (colored choropleth map units) AND the rich reference information on popular map tiles (e.g., Google, Microsoft Virtual Earth) without sacrificing map reading and interpretation ability and confidence. We believe that there are lots of times when reference and thematic data can work extremely well together to really benefit a map’s message (e.g., a soils map that shows terrain or a vegetation map that shows elevation). So, we wanted to build this functionality into Maker!, and allow people to make maps that show the best of both worlds.

The Problem with Transparency

The fundamental problem with transparency is that the color of semi-transparent map units can shift due to the visibility of color that lies beneath them. This is not at all surprising, but can make the basic legend matching task difficult, obscure the pattern of color on the map, or just as bad, make patterns appear out of nowhere. Here’s a look at what happens to colors using the same semi-transparent choropleth map units on different backgrounds. These are screen captures from early design mock-ups for Maker!.

The first image shows (hypothetical) opaque choropleth map units with a 7-class color ramp. The next three images show the same units at 50% opacity on top of Google terrain, streets, and satellite imagery. Notice how colors shift when compared to the opaque map at top? See how lightly colored units nearly disappear on the streets map, and darkly colored units nearly disappear on the satellite map? Yikes!

Mock-up of an opaque, 7-class choropleth map for Maker! (Google terrain)

Mock-up of an opaque, 7-class choropleth map for Maker! (Google terrain)

Same mock-up, at 50% opaque (Google terrain)

Same mock-up, at 50% opaque (Google terrain)

Same mock-up, at 50% opaque (Google streets)

Same mock-up, at 50% opaque (Google streets)

Same mock-up, at 50% opaque (Google satellite)

Same mock-up, at 50% opaque (Google satellite)

The Solution to Transparency

We employed three design solutions to ensure that semi-transparent choropleth maps in Maker! would work, despite potential map reading problems: 1) unit boundaries, 2) data probing, and 3) transparency control.

1) Unit boundaries. In Maker’s choropleth maps unit boundaries are color coded but remain opaque, even when unit fill color is semi-transparent. This gives map users some true color information to work with, and should improve their ability and confidence to spot map patterns or match colors to a legend. In other words, while unit fill colors can get you close, unit boundaries can get you the rest of the way there.

Screen-shot from Maker! showing opaque choropleth unit boundaries

Screen-shot from Maker! showing opaque choropleth unit boundaries

Corresponding legend for the above map

Corresponding legend for the above map

2) Data probing. We also took advantage of a relatively common and very helpful interactive map feature known as data probing. Exact values for any choropleth map unit can be obtained by clicking on them. In Maker!, we designed the data probing feature to go one step further and give values for all of the possible attributes associated with each map unit, not just the mapped attribute alone (see the scrolly list, shown in the probing pop-up below).

GeoCommons Maker! Data Probe

GeoCommons Maker! Data Probe

3) Transparency control. Finally, we gave mapmakers a transparency control, as well as a chance to take some responsibility for how well their maps communicate. The transparency control lets mapmakers decide what works and what doesn’t. Given the huge range of possible maps that can be made with Maker!, some user controls like this are necessary (as well as being kinda fun!). Here, transparency can be adjusted for a custom fit with any chosen tile set, color scheme, or other mapped data. Settings on the control (shown below) range from 50-100% opaque.

Screen-shot from Maker! showing the transparency control

Screen-shot from Maker! showing the transparency control

The Best of Both Worlds

Our decision to include semi-transparent choropleth maps in Maker! should give mapmakers and map users the best of both worlds. A semi-transparent choropleth is truly a hybrid map in that it can potentially offer all the advantages of combining rich reference data (i.e., underlying tile sets) with great thematic data (i.e. overlying choropleth units). Hopefully the choropleth maps coming out of Maker! will be easy to read and good looking, too!

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A new kind of election map

November 8, 2008

Update, Dec. 22: A few variations of the map technique are posted here.

2008 election results with population

We spent some of our spare time last week exploring data from the 2008 presidential election and thinking of some interesting ways to visualize it. Above is one map we put together.

One thing we sought to do was present an alternative to cartograms, which are becoming increasingly popular as post-election maps. Cartograms are typically offered as an alternative to the common red and blue maps showing which states or counties were won by each candidate, wherein one color (presently, red) dominates the map because of the more expansive—but less populated—area won by one candidate. Election cartograms such as the popular set by Mark Newman distort areas to reflect population and give a more accurate picture of the actual distribution of votes. A drawback of cartograms that we’re very aware of, however, is that in distorting sizes, shapes and positions are necessarily distorted, sometimes to the point of making the geography virtually unrecognizable.

Our map is one suggestion of a different way to weight election results on the map while maintaining correct geography. What we’ve done is start with a simple red and blue map showing which candidate (Republican and Democrat, respectively) won each county in the lower 48 states. Then, to account for the population of those counties (or, the approximate distribution of votes), we’ve adjusted opacity. High-population counties are fully opaque while those with the lowest population are nearly invisible. Against the black background, the highest concentrations of votes stand out as the brightest.

We’ll let viewers be the judge of its cartographic effectiveness, but we hope you’ll at least agree that it looks pretty cool!

Click on the image at the top of the post to view a larger version, or see it in a Zoomify viewer, or download the full size (suitable for printing).

24 Comments

ColorBrewer 2.0

November 4, 2008

I love ColorBrewer. All of us here at Axis rely on it almost daily and it’s helped us to make nice looking maps quickly; and that’s what good tools do, they make their users look really good at their jobs.

7+ years later, ColorBrewer is due for some changes and Cindy Brewer has been kind enough to ask us to hold the scalpel. Nothing major. Same great color schemes (of course), but a new interface and some new functionality to help ColorBrewer’s 2000 visitors per week get the most out of the experience.

We’re in the early stages of planning this project but we though we would open this up for some discussion amongst the ColorBrewer-using, Axis Maps Blog-reading masses.

QUESTION: What would you like to see in the new version? What should remain untouched? What do you love? What do you wish was done better?

Let us know your thoughts in the comments. Thanks!

7 Comments

The Golden Age of Cartography is Now

October 27, 2008

This is an exciting time to be a cartographer. Cartography has changed more in the past 5 years than in the previous 50, and the field is in the midst of an unprecedented revolution that has forever altered what maps can do, and how and why we use maps. How far have we come? I now see teenagers using on-demand, customizable maps rendered in real time from multiple, distributed data sources on their cell phones that automatically geotag and upload photos to their blogs while they sit on the bus. Five years ago, heck, one year ago this would have been science fiction, now it’s just a collection of geoservices on a $200 phone. As a result, mapping technology has quickly outpaced mapping theory and practice.

While much attention has (rightly) been focused on the technology that is enabling these amazing advances  (Google Earth, mash-ups), I think the equally significant change is why people are making maps and the role maps now play in our everyday lives.

Take “pocketcasting” for example, the next step in social networking, where folks geo-broadcast their locations so they can see where their friends are at any given moment allowing unplanned meetings (“I’m at this cafe!” as a kind of mass, voluntary, geo-voyeurism). This adds a degree of instantaneous spatial awareness to our social lives that would have been impossible without the serendipitous convergence of technologies like GPS, wireless networks, and customizable on-demand maps. Other new ways the public is using maps include monitoring traffic conditions in real-time or using Google’s wonderful streetview to check-out a potential new home virtually. One thing is clear: Maps have become fully integrated into the fabric of our lives in ways we couldn’t have imagined a few years ago.

Beyond the popularity of these maps, however, has been the complete blurring of the distinctions between map maker and map reader, data provider and data user. It is precisely this tectonic shift in the world of cartography that underlies the philosophy of GeoCommons Maker!, the product we’ve been jointly developing with the powerhouse team at FortiusOne, described by the O’Reilly Radar as “a Flickr/Swivel/YouTube/Scribd of geodata.” Maker is at the vanguard of the democratization of cartography and the promise of Web 2.0 services that eliminate the need for expensive software/data for most casual ‘citizen cartographers’ and allows people to make great looking maps quickly while guiding them through the process. We here at Axis Maps feel strongly that powerful tools (e.g., desktop GIS) aren’t much good if they don’t provide guidance – it’s like giving the keys of an F-16 to someone who doesn’t know how to fly. Furthermore, while an F-16 is amazing, few folks actually need one. Same with $30,000 mapping software.

One of the reasons we like Maker! is that it empowers people – who otherwise would never be able to participate – to make their own maps and start publishing, sharing, and commenting on geographic data and the things we learn from those data. High-end, professional cartography is not going to disappear, and the world will always need premium map products (such as National Geographic Atlases or legally-binding land surveys). The same is true of professional authors and photographers; neither blogging nor Flickr have eliminated the need for these professionals, rather they have opened up these activities to a much larger group and drawn people into the process, rather than relegate them merely to being spectators to the process.

One thing is clear: As the GeoWeb/Web2.0 revolution continues, we need to move beyond paper map thinking and starting seeing maps much more broadly as services that can be integrated with other services. As a professional cartographer this means to me that the “rules” of cartography established through a century of study and practice are now up for grabs at the very moment mapping finds itself in a multi-billion dollar spotlight from both the private and public sectors. Some of the biggest companies in the world (Google, Microsoft, Yahoo!) are betting a big chunk of their digital future on maps and the central role they want cartography to play in their digital empires. With the backing of these companies, digital, on-demand maps have gone from technological curiosities to everyday tools worth billions of dollars. This begs the question: Where is mapping headed and what might our maps do for us in 10 years?

Further questions we need to think carefully about (these are the sorts of questions that keep us up at night!!)…

  • How much of what we have learned about static maps—both in practice and theory—holds true when these maps become animated, interactive, and customizable?
  • What are the relative merits of 2D versus 3D?
  • How do we keep users from becoming disoriented and lost in 3D immersive maps?
  • What are the perceptual limits of animation and for what kinds of map reading tasks (e.g., rate estimation, change detection) are animated maps especially well-suited (and how could those tasks be better supported)?
  • How can we reduce the problem of “split attention” in immersive and visually-rich environments like Google Earth?
  • How can we create intelligent Web-based software that is both easy to use and powerful? To what degree can the map-design process be automated to further the democratization of map-making? How can we help novices to think like experts?
  • What should our map interfaces look like and why? How does the map interface structure the user’s experience? How do we know if our map interfaces work?
  • Who benefits from these billions being invested in mapping?
  • How does this technology change the way we do business and the way we interact with each other?
  • What are the limitations and liabilities of decentralized data structures and technologies that run on volunteered geographic data?
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