Tag Archives: visualization

Periodic Spirals—and the Third Dimension

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I ran across an image similar to the above on page 86 of Philip Ball’s marvelous little The Elements: A Very Short Introduction, part of an impressive series from Oxford University Press. (I highly recommend these wee volumes, which offer a lot of bang for the buck, at least in the limited selection of titles I’ve perused.)

Anyway, the image. It shows the “lemniscate spiral” of a certain William Crookes (not exactly a household name, but an interesting fellow nonetheless). I have previously blogged about the periodic table, but I find this attempt particularly intriguing. Crookes was trying to visualize the relationship between various elements in three dimensions, which is the kind of thing we do without thinking nowadays, but in the late 19th Century… Of course you’d have to try constructing a convoluted contraption to convey your idea!

That’s what I find interesting about the image: a 19th-century scientist would use an image depicting the hypothetical three-dimensional object in physical terms. Because the abstraction of three dimensions could not (easily) be conveyed pictorally without reliance on real-world elements to suggest the construct extending outside the plane of the printed page. Honestly, I have no idea whether Crookes physically constructed his “lemniscate spiral” or not, but I’m guessing not. Which is what makes me think this the image is a way of communicating the idea.

Whereas modern tools allow us to visualize data in three dimensions and, at some level, conceive of things in three dimensions, such virtual luxuries were unavailable to Crookes and his contemporaries. Thus the conceit of the physical object.

Interestingly, I know of no modern three-dimensional visualizations of the periodic table. Perhaps someone can point me to something…? But if they exist, I bet they aren’t depicted as physical objects.

Side-by-Side

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I know I already posted one hurricane-related entry this week, but I have another. This one is related to a press release from the National Center for Atmospheric Research (NCAR) about a new technique “that provides a detailed 3-D view of an approaching hurricane every six minutes.” I was curious what a 3-D view of an approaching hurricane might look like, so I followed the links, and…

I got the above. Hmmm.

To be fair, the page makes no claim for the above to be any kind of 3-D view, but it does supposedly offer a “side-by-side” comparison of radar data (on the left) and “NCAR’s ARW experimental forecast” (on the right). An animation shows the evolution of the hurricane, and as the caption duly notes, “The radar vantage point is stationary, on the Gulf Coast, while the ARW viewpoint follows the hurricane itself.” And therein lies my cavil (I’m trying to find synonyms for “gripe”).

The presentation of the images should facilitate side-by-side comparison; instead, the camparison seems hampered by the graphical choices. The change in background color strikes me as mildly annoying, but the field of view of the two images is also slightly different, and the manner in which the left-hand image obscures the state lines makes comparison even more difficult. It’s rather hard to tell how well the model replicates the observed behavior of the hurricane.

The animation only exacerbates the problems because the simulation follows the eye of the storm whereas the Doppler radar remains stationary (as noted in the caption). C’mon, folks, this is data! You can plot it however you want! Why not present it in a way that allows us to get a real feel for how well the computer model matches reality?

How to do it right, in brief: make the background of the two (observed data and computed data) as similar as possible, in terms of scale and markings (e.g., state and county lines), then plot the same quantities using the same color bar (which, as far as I can tell, is what they did in the above example). Would that be so hard?

Building Towers in the Tempest

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The teeny-tiny image above comes from a NASA press release about a energy flow near the eye of a hurricane. A high-resolution TIFF of the same inexplicably eliminates the captions, leaving one with an unlabelled, multicolored, meaningless image—my favorite!

The image above bears some resemblance to a previous visualization of Hurricane Bonnie, but I’m actually not going to complain about this awful image presented with a press release of some interest. Instead, I’m going to call attention the remarkable new visualization that supports the above story. The full video (at several resolutions) and numerous stills (at resolutions of 320×180 or 144 times larger, but none in between) can also be downloaded from Goddard’s Science Visualization Studio website.

The full piece does a respectable job of explaining the whole “tower cloud” concept shown in the above image. I recommend watching it. The visuals and narration mesh nicely, telling a pretty good story. Furthermore, if you’re interested in how such media pieces come into being, you can take a look at an illustrated storyboard for the video. Well done!

“Visualizing” Astronomy

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Geez, everyone’s getting into “visualizing” nowadays! Harvard’s Center for Astrophysics (CfA) just announced its “Visualizing Astronomy“ lecture series, an effort which I commend.

That said, looking at the image above, which runs as a little banner at the bottom of the aforementioned page, gives me pause. All gorgeous pictures, which seem to map one-to-one to the first four presenters in the series… At least, I recognize two off the bat. First on the left, we have Robert Hurt’s Orion Nebula (with a bit of Zoltan Levay’s Hubble version thrown in), right next to Travis Rector’s Rosette Nebula. And, okay, I recognize the one on the right as well: the recent Spitzer-Hubble-Chandra image of M82, which intersects with Robert Hurt and Zoltan Levay and (I guess) Daniel Wang, since he works with Chandra. The second from the right… I’m sure I could dig it up if I had the time, but I’m thinking I can rely on a reader (or two) to set me straight (as it were).

But here’s the point I want to make. All noble images, all four of ’em! But to have them represent “visualizing astronomy” is like having photos of animals (all shown at the same scale, no less, from amoebae to ants to elephants) represent visualizing zoology! The process of visualization seems to me so much more complex, so much richer than compositing imagery of various wavelengths (again, a noble aspect of the endeavor, but only one aspect) that I can only look upon these four wee images with a little sadness. What about visualizations of three-dimensional datasets, near and dear to my heart? What about diagrams and charts, however maligned they may be? What about space art, such as it is? Dang it, there’s a universe of visualization opportunities out there! And CfA, as the text on the lecture page suggests, intersects with many such efforts.

The word “visualize” sounds good. It has a ring to it. People take notice when they hear it. I know, after all, it’s part of my title. But we should make sure it maintains its aura, its mystique, by not curtailing its breadth of meaning.

This, BTW, is a small community. I’ve probably just offended somebody I know (and like). Sigh.

Cycling on Water

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Images like the one above would captivate me as a child. Better even than some Richard Scarry book, they offered a chance to escape into a single-image story that quite often related to the real world (or universe) around me. I specifically remember water-cycle images as utterly entrancing.

I came across the above in a NASA press release on changes in freshwater distribution, which has some other interesting images that I’ll get to in a moment. But the diagram showing the water cycle usually has lots of arrows in it, kind of like the one associated with the Wikipedia article on the topic. But this one goes for a more organic style, replete with numerous labels (e.g., “soil heterogeneity”) but only a few, sparsely distributed arrows. I’m not sure I feel the connections as well as I’d like.

Of course, nowadays, one also has animations to illustrate the process, such as the 44.0MB epic (oddly entitled “EnergyUncomp640.mpg”), also linked to by the press release. In the animation, we see elements of the water cycle played out in sequence—cleverly coincident with the day-night cycle, beginning at dawn with evaporation and ending at night with clouds disappearing stage right. Again, no arrows. I wonder if the temporal element obscures the underlying process… In other words, does the beginning-to-end sequencing of a cycle not do justice to its cyclicity?

Nitpicks, but… I’m curious.

Both the animation and a high-resolution version of the above show up on GSFC’s excellent “Water Cycle” site, which offers much more detail on the processes involved and pays special attention to the human role in the environment.

But back to the aforementioned press release. It also shows diagrams of data from the Gravity Recovery and Climate Experiment (GRACE), which appear along the right-hand side of the web page (too tricky to reproduce here, since they show up as either uselessly tiny or overly large images on the site). One thing I like about the two images is that they use the same color scale (i.e., a given color represents the same quantity in both images); unfortunately, the color bar is unlabelled, so we have no idea what the units are, or really, what quantity we’re talking about at all. What annoys me, however, is that the sorry old crimson-to-violet color bar rears its ugly head, so we have a rainbow of colors with no logical change represented by, say, the shift from warm colors to cool colors (if there is such a meaning, it’s not described in the captions or in the text of the press release).

So, for example, if we have a map of the United States like the one shown in the press release, I’d want to know that the red regions represent, say, areas with decreasing water resources whereas green regions represent increasing freshwater availability. The color bar wouldn’t have to be labelled with units, but including words that describe what the colors mean would be nice—certainly better than numbers devoid of any context.

The GRACE website also includes a truly bizarre visualization of Earth’s gravitational anomolies. I, um, really don’t know quite what to say. Perhaps I should sleep on it…

Questions

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This may seem lazy, but… We ended our visualization conference today with a discussion of imaging philosophy. And the above image came up in discussion. It’s the (in)famous “Pillars of Creation” image of the Eagle Nebula, taken by the Hubble Space Telescope, of course, and it’s gotten about as much visibility as any astronomical image of the last few decades. So without much ado, maybe I could just pass along a few questions for those of you who consider yourself members of “the general public” (whatever that means, anyway).

Did you know that the Eagle Nebula doesn’t shine in those particular colors? In fact, it looks more like this pink-ish image from Rob Gendler, which is at least closer in color to what you would see with your eye up to a telescope. Does it bother you that the image represents something that you wouldn’t see through the eyepiece of a telescope? Do you think image specialists are lying to you by presenting images in this manner? (You can learn how the Hubble team makes thir color images by reading “Behind the Pictures” at their website.)

For that matter, how do you think we should describe images like the one above? They’ve often been called “false color.” Does that sound appropriate? What does the term suggest to you? Hubble describes such images as ”representative color.” How does that sound?

As you might guess, those of us in the biz have our own ideas, but I’m curious if anyone out there would like to share their opinion(s).

Thanks!