Visualization as I see it.

Category Archives: video

Tweets During the Japanese Earthquake

Twitter has just published a couple of videos that visualize the flow of tweets before and after the March 2011 earthquake.

The first video shows @reply tweets in the hour preceding and following the earthquake, to (pink) and from (yellow) Japanese Twitter accounts.  You can clearly see the sudden jump in the volume of tweets following the earthquake.


The second video shows tweets originating in Japan (red) and then being retweeted (green) around the globe in the hour following the earthquake.

Twitter reports that the volume of tweets spiked to 5000 tweets per second five times in the hours following the earthquake and tsunami.  A vivid example of Twitter’s reach as a global communications tool.

The Choreography of Sorting Algorithms

As a computer science undergraduate I spent many hours learning various sorting algorithms. Pseudo-code and static diagrams were used to illustrate the implementation and processing of these algorithms. Now (almost a quarter of a century later!) it seems algorithms are still an important part of computer science education. What’s changed is that Web 2.0 technologies are being used to aid understanding.

The video clip shown above represents the Bubble Sort algorithm realized in the style of a Hungarian folk dance. Whether this represents the best visualization of sorting algorithms to date, I’m not so sure, but it’s certainly the most bizarre I’ve seen and is strangely compelling. The clips were created at Sapientia University, Romania and choregraphed by Füzesi Albert.

Below are several other folk dances choreographed to implement various sorting algorithms.

Insert Sort

Shell Sort

Select Sort

GOCE Reveals Gravity Map, ESA Conceals It

The ESA has just announced that their GOCE satellite has collected enough data “to map the Earth’s gravity with unrivalled precision”.  Accompanying the press release was the animation (shown above) of the “geoid” model derived from the new data set.

Unfortunately, the animation lacks the most fundamental feature required of all visualizations: a key to help us make sense of what it actually shows!

The text accompanying the animation sheds a little light on the visualization:

The geoid is the surface of an ideal global ocean in the absence of tides and currents, shaped only by gravity.

If I were to hazard a guess, I’d suggest that the visualization shows the earth’s crust, with a height field and colour map applied to it.  The latter two possibly encode the strength of the gravitational field and/or the height of the idealized global ocean (the latter being derived from the former).

The point is I shouldn’t have to guess!  This important data deserves better treatment.

If you know what the visualization encodes then please leave a comment below.

[ Update: 8 April, 2011 ]

I had this quick response from the ESA regarding interpreting the Geoid visualization:

The colours in the image represent deviations in height (–100 m to +100 m) from an ideal geoid. The blue colours represent low values and the reds/yellows represent high values.

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