Archive for the ‘Uncategorized’ Category

Spatial Humanities

July 26th, 2011 by Robert Simmon

There’s an interesting article in today’s New York Times about mapping historical landscapes: Digital Maps Are Giving Scholars the Historical Lay of the Land.

Few battles in history have been more scrutinized than Gettysburg’s three blood-soaked days in July 1863, the turning point in the Civil War. Still, there were questions that all the diaries, official reports and correspondence couldn’t answer precisely. What, for example, could Gen. Robert E. Lee actually see when he issued a series of fateful orders that turned the tide against the Confederate Army nearly 150 years ago?

Now historians have a new tool that can help. Advanced technology similar to Google Earth, MapQuest and the GPS systems used in millions of cars has made it possible to recreate a vanished landscape. This new generation of digital maps has given rise to an academic field known as spatial humanities.

Along with some nice examples.

2011 GRC Visualization in Science and Education

July 18th, 2011 by Robert Simmon

Although I got back from the 2011 GRC Visualization in Science and Education conference Friday night, my brain still hurts (in a good way). Thanks to Liz and Ghislain for their superb job as conference chairs. To me, the theme of this year’s conference was salience (more precisely, perceptual salience)–the ability of our visual system to focus on one thing at a time, to the near exclusion of everything else.

Hold one hand out in front of you, with the thumb up, and focus on the thumbnail. This is the limit of your locus of attention: about one degree. Away from that point everything else in your visual field fades into the background. For data visualization this is both an advantage (you can draw people to the important parts of an image) and a drawback (it’s impossible to pay attention to two things at once, and it’s easy to have your focus shifted unintentionally).

I’ll have some examples, and interesting bits from the presentations and discussion, in the next few days and weeks.

The Impact of Puyehue-Cordón Caulle

June 21st, 2011 by Robert Simmon

Every once in a while we get satellite imagery that shows things that are hard to imagine, like floating rocks. It’s helpful to have a different persepctive, like this series of photographs collected by The Atlantic. Fantastic.


May 20th, 2011 by Robert Simmon

Here’s a sneak peek at the site-wide redesign we’ll be launching next week. Let us know what you think (not that we can change anything at this point, but we’ll keep any critiques in mind for version 3.1). [Design primarily by Cuban Council, implementation by Paul Przyborski & Kevin Ward.]

Front page screenshot

Our home page.

images screenshot

The images page. Image of the day and natural hazards are combined, which will hopefully encourage browsing.

features screenshot

Top level of the features section. We've put more emphasis on new stories, and made the topic and date sorting options more obvious.

Map of the Ancient Mississippi

May 11th, 2011 by Robert Simmon

Historic flooding along the Mississippi River gives me an excuse to show another of my favorite maps, from Geological Investigation of the Alluvial Valley of the Lower Mississippi River.

Map of relic meanders on the Mississippi.

This map, published in 1944, shows the location of the Mississippi for the past 1,000 years or so.

Each color represents an old channel, dating back 1,000 years or so. Those that correspond to historical records are dated, while older channels are ordered according to the principle of superposition (newer sediments on top of older ones). Many of the surface layers are still visible in satellite imagery. High-resolution, geolocated maps from Cairo to the Gulf, along with major tributaries, geological maps, and cross sections, are distributed by the U.S. Army Corps of Engineers.

Since I was (slightly) critical of the New York Times graphics department yesterday, I’ll show a Times map that is one of my favorite visualizations today: a map of shaking intensity and slip during the 1906 San Francisco Earthquake.

New York Times map of shaking intensity from the 1906 San Francisco Earthquake.

From the New York Times article: The Ground Shook, a City Fell, and the Lessons Still Resound. April 11, 2006.

Aside from being elegant, it’s data-rich without being cluttered, and multivariate. It shows shaking intensity (in two dimensions), fault location (in two dimensions), slip along the San Andreas (one dimension), urban locations (two dimensions), and has three layers of direct labeling (cities, faults, and slip). The key is adjacent to the data, and written in clear language. Compare the map from the Times to the equivalent from the USGS:

USGS map.

USGS Earthquake Hazards Program. ShakeMaps: 1906 San Francisco Earthquake.

The New York Times version both has more data and is more readable. Why? First off, the Times uses a subdued, discrete, color palette that shifts through a small range of hues. This allows other information to be layered into the map. The USGS, in contrast, uses a rainbow of hues at maximum saturation. The rainbow palette [at some point I’m going to do series of posts on color palettes, but for now i’ll just point to Color Brewer to explain the importance of appropriate color maps in data visualization] uses the full spectrum and is so saturated that there are very few colors left over for additional data—notice how the red fault lines on the USGS map disappear in areas of intense shaking. The dark ocean in the USGS version also competes visually with the data-rich areas of the map.

The New York Times also forgoes the use of terrain data in their map. It adds a lot of great context to the image (the San Andreas creates a distinct valley), but at web resolutions shaded relief is very difficult to pull off. The high frequency contrast distracts from the other data in the map. At larger sizes, or printed at high resolution, the terrain could be added back in (but it still needs to be treated carefully—see Relief Shading for advice). As a result, fine details in the faults and the boundaries of urban areas remain legible.

My favorite part of the Times map is the inclusion of the amount of slip at various locations on the San Andreas: it’s so much more informative than merely indicating the epicenter. Earthquakes—especially big earthquakes—aren’t points. They occur over a two dimensional area (reduced to a one dimensional quantity on this map). Increased slip correlates with increased shaking, which tells a story. That’s what makes this map so powerful. It’s a narrative of cause and effect, which is a quality of the best data visualizations.

A Hierarchy of Perception

May 9th, 2011 by Robert Simmon

Last week, Jessica Ball of the American Geophysical Union’s Magma Cum Laude blog pointed out this map of natural hazards in the U.S., published by the New York Times:

New York Times map of natural hazard in the United States.

By MATTHEW ERICSON, JOE BURGESS and BILL MARSH/THE NEW YORK TIMES. Sources: Sperling’s Best Places; National Oceanic and Atmospheric Administration (tornado map); University of Miami (hurricane map); U.S. Geological Survey (earthquake map).

The map has many of the design virtues common in graphics from the Times (clean, focused on the data, clearly labeled, small multiples), but when I first viewed it I had trouble parsing the data. It took me a while to figure out that hazard was indicated by color, and the size of each circle denoted ancilliary information (population).

It turns out that our eyes &amp brains perceive area more strongly than color. Here’s a list of ways to visually compare quantities (described by Bang Wong in his Points of View column for Nature Methods), in order from easiest to hardest:

  1. Positions on a common scale
  2. positions on the same but nonaligned scales
  3. lengths
  4. angles, slopes
  5. area
  6. volume, color saturation
  7. color hue

I suspect I’m not the only person who would consider the size of the circles more important than the color, and assume size was correlated with hazard. I had to carefully read the key to figure out the proper way to read the map. Perhaps using size to encode hazard, and color (or opacity, or icons) for population would have worked better.

2011 ISRSE Wrap-up

May 6th, 2011 by Robert Simmon

I recently had the opportunity to attend & give a presentation at the 2011 International Symposium on Remote Sensing of the Environment in lovely Sydney, Australia. (OK, not so recently—the conference ended on the April 15th. I blame jetlag.) Just over 60 people turned up for the talk, which was mostly about our visualization of Eyjafjallajökull. (Which means I had to attempt to learn how to pronounce “Eyjafjallajökull.” Luckily I don’t think anybody made it from Iceland to Sydney to critique me.) If you’re interested, I’ve posted Keynote and PDF copies (originally prepared for last years’s fall AGU).

During sessions many of the talks were a bit on the technical side for me, so I ended up preparing material for NASA’s portable “hyperwall”—9 HDTV screens linked together. It’s useful for either high-res animations, or small multiples. With relatively thick bezels on the monitors, simultaneous display of 9 images worked particularly well:

Photograph of the NASA hyperwall at ISRSE.

A sequence of images on the NASA hyperwall at ISRSE 34. These show the continued desiccation of the Aral Sea from 2000 to 2009, with a slight rebound in 2010.

Compare the small multiples on the hyperwall with the sequential display of the same images from the Earth Observatory’s World of Change.

During my talk I promised the audience that I’d update the blog more frequently, so there should be more posts in the future. I sometimes struggle for good ideas, so if you have a suggestion, please drop a note in the comments.

International Iconography

April 22nd, 2011 by Robert Simmon

One of the best things about international travel (at least to a geek like me) is to see how different cultures approach design and signage. Here’s a few from Blue Mountains National Park, near Sydney, Australia.

Sign showing the difficulty of hikes near Wentworth Falls.

Hikes near Wentworth Falls.

Signage along the National Pass trail.

Limited options along the National Pass trail.

The Challenges of Picturing Floods

January 20th, 2011 by Robert Simmon

Over the past week or two, there has been severe flooding in Australia, Brazil, Sri Lanka, and the Phillipines, but all we’ve shown on the Earth Observatory is the flooding in Australia. Why? Here’s a sampling of images of Rio de Janeiro since January 12:

Satellite image of Ri de Janeiro

January 12, 2011

Satellite image of Rio de Janeiro

January 14, 2011

Satellite image of Rio de Janeiro

January 16, 2011

Satellite image of Rio de Janeiro

January 18, 2011

Earth is cloudy. Especially in the tropics. Even more especially when there’s enough rain to cause flooding. The satellite imagery we have easy, fast, and free access to (for example, check out the twice daily MODIS imagery of São Paulo) is primarily based on visible and infrared light, which can’t penetrate clouds, so for many floods we can’t show anything useful.

In addition, the damage in Brazil, Sri Lanka, and the Philippines was caused by flash floods, landslides, and debris flows, which are all much smaller scale than the rivers overflowing their banks near Brisbane. In satellite imaging there’s a tradeoff between spatial resolution (detail) and temporal resolution (frequency) so there are fewer opportunities to capture the high resolution data necessary to show relatively localized events. To view something like a landslide, we have to have both a break in the clouds and the opportunity to aim a high resolution sensor. Which occurred this morning:

Satellite image of Rio de Janeiro

With clear skies and an overpass of Earth Observing-1, we may have an image of Teresopolis, Brazil by tomorrow.

P.S.: Despite the dispassionate view afforded by satellites, my thoughts go out to the victims and their families.

Update: For some reason the satellite never acquired the data, and the next viewing opportunity won’t be for another few days.