Monthly Archives: October 2006

Stunningly Incomprehensible

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Words fail me on this one (well, not really). How incomprehensible is it? Let me count the ways.

First off, we’re confronted with the somewhat cryptic information that we’re seeing the “cosmos” at a distance of 450 million light years. Mmmm hmmm. Then we have a color bar at the bottom, sans units, that tells us that the values range from –1.0 something to 4.3 something. Other labels appear scattered pell-mell across the image… “Fur-For”? “Per-Peg”? What is an Average Jane to make of these? (They’re short for “Further Fornax” and “Perseus-Pegasus,” BTW. I’ll even make the obnoxious grammarian observation that it should be “Farther Fornax” if anything.) And to add insult to injury, the red typeface blends right into the color scheme of the plot!

What saddens me most about this image is that it represents a spectacular result poorly communicated. What you’re looking at, FYI, is a color-coded representation of matter density within a thin sliver of the Universe at an approximate distance of (you guessed it) 450 million light years. The press release correctly identifies this as “the largest full-sky, three-dimensional survey of galaxies ever conducted” (based on 2MASS data, just so you know). How kewl is that? You wouldn’t know from this picture.

(If I were petty, I would note that the headings on the images don’t even match the captions provided in the press release from the Royal Astronomical Society, at least as it was emailed to me. For example, the caption for the image above reads, “The reconstructed density field, evaluated on a thin shell… at 45 million light years. The main overdensity, Shapley, is shown in red and green. Other overdensities are Rixos F231\526 (RIX), SC44, C19, Pisces (Pis), Perseus-Pegasus (Per-Peg), C25, C26, Hercules (Her), Abell S0757, C28, C29, C30, SC 43, Leo, Abell 3376, C27 and C21. The voids (blue) are V4, Further-Fornax (Fur-For) and V15.” Emphasis mine. But I’m not petty. Oh, and the picture is correctly labelled; the caption is wrong.)

The academic paper presents the same images as black-and-white contour plots, so I can only assume that the researchers believed themselves to be translating their results into user-friendly format simply by adding garish color.

Allow to digress for a moment to explain why I see this as such an egregious mistake. My two-bit definition of science visualization goes something like this… We make images from data (i.e., ones and zeros) for essentially one of three purposes: 1) communication to oneself in the form of data analysis, 2) communication to peers, often in the form of a graph or contour plot, and 3) communication to a general audience. The first two purposes depend heavily on well-developed visual language—for example, knowing what variables you’re plotting against one another, knowing what color-coding means, etc.—that often tend to be very specialized. Those of us who have been reading cartesian coordinates for most of our lives forget what it’s like not to be exposed to that visual vocabulary on a day-to-day basis. Needless to say, scientists tend to communicate via an extremely sophisticated visual language (that furthermore varies from discipline to discipline). The biggest problem occurs when scientists try to make the leap to the third form of visualization—communicating to the general public. It’s difficult to translate their complex visual language into a visual vernacular. (More details on my “personal paradigm” are available as part of my “What Is Viz?” PowerPoint, but be warned that you need to read the comments for each slide; otherwise, it’s just a bunch of pictures.)

Thus, the fundamental issue I see here can be likened to a mistranslation. The image above uses a very specific vocabulary (e.g., false color, Aitoff projection of a sphere onto a plane) to describe a small part of the Universe. Without attempting to translate the truly challenging aspects of the image, the presentation of candy-colored data sans specific quantifying information in fact results in a terribly confusing message.

Oddly enough, we have played with an earlier version of the 2MASS data as part of the Hayden Planetarium Digital Universe, so I’ve seen (in 3-D) the galaxy data upon which this is based. The data certainly lend themselves to a 3-D representation, and I can image a fly-through in which the matter distribution is represented by 3-D isosurfaces, or if a lot of rendering time were at one’s disposal, by volumetric rendering (similar to the manner in which some dark matter simulations are depicted.

Holy Ozone, Batman!

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(N.B. that the animated GIF above is rather large, about four megabytes, so it could take a little while to load in your browser. If you prefer, a smaller version is also available online.)

Not a new story, really, but an interesting choice of animation to illustrate it. New data from the SCIAMACHY instrument onboard the European Space Agency (ESA) satellite Envisat shows a record-breaking ozone hole—after a few years of improvement, the hole seems to be deepening once again.

When I first glanced at the above image sequence, I reacted with a basic, nonplussed “hmmm.” The data in the middle look screwed up, and I’ve never been a big fan of false color, so I scanned down and started reading the article on the ESA website. When I glanced back at the animated GIF, it was much more interesting! How embarrassing to discover that I’m as much a victim of our culture’s impatience effect as the museum- and planetarium-goers I’m trying to entice into taking lengthier looks at things.

Basically, the above animation does’t hit its stride until about halfway through (mid-September), at which point the change is quite striking (and depressing): a big, black hole develops over Antarctica, swallowing up the continent’s outline like a killer blob from a 1950s sci-fi film. And like the slower-paced films of that era, you have to wait a little while for the punchline.

The only other issue I have with the image is that it doesn’t quite underscore the story, namely that the ozone hole is “deeper” than at any time in the last eight years. To communicate that, the page of figures on the ESA website relies on a bunch of wiggly graphs. All well and good, but how ’bout a side-by-side comparison of two years, even as a still image? Or perhaps a viewer that would allow you to select two years to show side-by-side, clicking through dates in lock step? That would be an impressive and intuitive interface.

Environmental data demand good visualization, for personal impact and political import both. Sadly, we have no superheroes to save us from the ozone problem, and with humanity’s track record for addressing long-term problems, we need all the help we can get.

Mapmaking

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A slow Monday. So I’ll highlight a reference I came across while reading the book Weighing the World, by Edwin Danson. (Danson’s book describes the processes of surveying in illuminating but excruciating detail; what struck me as most interesting was both the variety of individuals involved and the dramatic sweep of the effort, risking life and limb to determine once and for all that, in fact, Earth is not perfectly spherical, for example.)

Anyway, the reference is Antique Maps, by Carl Moreland, but you can read it online at its very own website. Now, the goal of this tome is to introduce prospective buyers to the essentials of map- and print-making, but the information passed along makes it well worth the occasional digressions. For example, Chapter Two, “The Printing of Old Maps,” gives a succinct and worthwhile survey of techniques that formed the foundation of all diagrams and printing techniques from the 16th to the 19th Centuries.

This historical stuff fascinates me, as my previous post about dodo lithographs may suggest. Printing maps made maps worthwhile in a way that drawing maps was not: a printed map could be amended and improved upon, and it could effectively incorporate input from myriad voyagers, surveyors, and sailors. In my opinion, that conceptual transformation has few parallels in the history of human thought.

More on that in posts to come…

Trying in Vein

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Yes, I live in New York, but no, I did not attend NextFest while it was here. I nabbed the above image from their website, though!

It shows a Luminetx VeinViewer in action. Basically, the gadget takes an infrared image of a part of one’s body then re-projects it onto the corresponding surface of one’s skin. Veins don’t reflect the near infrared light, but the surrounding tissue does, so you get a high-contrast view of the veins. Hence, “VeinViewer.”

What I find amazing about the above image is that it communicates that concept fairly clearly—okay, not the near-infrared part, but the general function of the device. You see the image above, and you say to yourself, “Wow, I can see his veins!”

Now, that may not seem like such an accomplishment, but take a look at the images from the Luminetx gallery. Actually, I’ll save you the trouble and link one of the images below:

I mean, okay, the kid looks happy, but what’s that on his arm? It looks like he got a weird tattoo! (Or was the victim of some poor Photoshop work.) Having seen the other image, I understand what’s going on, but the image doesn’t read as clearly as the one from the NextFest site. Offhand, one might think that the real-world image from Luminetx would communicate the concept better than the somewhat stylized image of just the backlit hand. But the composition, lighting, and sheer simplicity combine to distill the concept in an impressively lucid (and certainly more aesthetically pleasing) manner.