Boing Boing is showing a great information visualization concerning a case in which a college president has been accused of plagiarising his Ph.D. thesis, here. It consists of nothing more sophisticated than a yellow highlighter and a grid of thumbnail images of pages, but I think it conveys the message very effectively.

It's a pretty obvious observation that the graphic conventions we use when illustrating mathematical objects can have a lot to do with how we think of them. The standard way the computer science textbooks draw trees is like a biological tree, but upside-down, with the root at the top and the leaves at the bottom:



When we view a tree in this way, the traversal order given by breadth-first search forms a geometric pattern that scans left-to-right across the vertices in a single level of the tree (conventionally, these vertices lie along a horizontal line), then the next level, and so on, much as one reads English text left-to-right and line-by-line. And this level-by-level ordering can be useful for conveying the idea that breadth-first search sorts vertices by their distances from the root.

But the breadth-first search algorithm itself, as it is usually described, does not progress level-by-level.( Read more... )

Infosthetics: the beauty of data visualization. From Ping (a Japanese magazine, but the article is in English) via MF. Lots of pretty visualizations, with surprisingly clear descriptions of what they visualize.

ETA: Ping is syndicated on LJ as pingmag. I also very much liked their recent article on Persian calligraphy.

leonardo_m just posted a fine collection of links to algorithmic art. His link to nodebox attracted my attention first as it is based on Python on the Mac, but the art he shows in his post from chriscoyne is more visually appealing to me: of the fractal L-system type, but with very good control of color, line, and tonality. I also found the image below (from nodebox, created by Tom De Smedt) especially intriguing; it's a visualization of the pattern of motion of a flock of simulated birds, but I'm not sure whether it was intended more as a visual aid for understanding that motion or as a piece of abstract art.

( Cut for large image )

Via placemap: Flow Map Layout, Phan et al., InfoVis'05.

The idea seems to be to visually express how much movement there is from different geographically placed sources to a single sink, by drawing the movement as a confluent tree in which physically nearby sources are merged together, and the thickness of a confluent edge indicates the amount of movement along that edge. So it's closely related to confluent graph drawing, but not the same, because the initial data is not so much a graph as a spatial numeric field (the amount of movement from each site) and the confluent tracks merge but don't unmerge. However, there is some graph drawing involved, in placing the edges and merge nodes of the resulting tree so that it doesn't cross itself.

After giving my last two lectures of the school year today, I'm not up for much more than posting pretty pictures, so:



( The explanation )

Via nikolasco: tag cloud. Just an alphabetical listing of the tags for a set of blog entries (sort of like this one), but with dynamically resized fonts, so that the tags more closely related to the one you're hovering over get larger. An interesting way to visualize proximity.

Via Eric Eggertson: Google Newsmap. Uses treemaps to visualize recent news stories, with apparently a very shallow hierarchy (Google's categories, then the stories themselves). Larger boxes represent stories from more sources, and darker boxes represent older stories. Colors represent categories. Checkboxes control which national version of Google News to use and which categories to include. Headlines only, but with popups giving the caption if one hovers over a headline. Very slick, interesting way to get a quick gestalt of the news.

I don't think I'd use it much myself, though — because of the shallow hierarchy, the treemap layout doesn't really convey a lot of information, it merely makes it difficult to scan through all the headlines on the page. And I'm not very enthusiastic these days about web sites that I have to check back on regularly in order to find new content, I'd rather use my RSS aggregator for that.

Via Ramesh Jain: Interactively fly through a time-ordered display of recent etsy listing photos (etsy appears to be an ebay-like site for handcrafted items). Doesn't seem very useful as a user interface to the site (for one thing, there's too little control of subject matter or timescale), but it does give a good visual impression of what's going on overall there. And it's an interesting twist on the usual fisheye approach to focus-of-attention issues to have the large easily viewed items around the periphery of the view and the clutter of small items in the center.

I don't see that there's anything specific to etsy here; I think it would be more interesting to see similar streams of photos from ebay, flickr or recent LJ images, but maybe the volume of images on those sites would overwhelm the spatial metaphor, e.g. forcing the navigation to slow to realtime or worse.