Headsets Provide a Large Increase in Addressable Screen SpaceAugust 22, 2014
Edward Tufte is famous for promoting the idea of data density, that is, the number of data points that are portrayed, divided by the area in which they are visible. A simple bar chart has one data point per bar (the height of the bar), which is not very efficient; there are more compact ways of presenting the same information (a table may be more appropriate, or even the points on the graph).
Contrast a bar chart with this graph of Napoleon’s advance (and retreat) on Russia:
In that graph, we can see the size of Napoleon’s army at each point in the advance, the temperature at many of his stops in the freezing Russian winter, the rough geographic location of his force, as well as the approximate dates of each visit, in one chart whose thrust can be understood in under five seconds, despite the unusual format.
Addressable Screen Space
The amount of data that’s possible to be displayed bumps up against some limitations. One limitation is the amount of data you have; it’s difficult to find exciting ways to map ten data points, because of the density constraints listed above. If you have more data (and more dimensions, say, like longevity AND income AND money spent on hospital care AND smoking rate AND height), things get more interesting. But as a general rule many problems don’t need complex visualization.
The second limitation is the amount of addressable screen space. Let’s face it - you can’t display as much useful information on an iPhone as you can on a laptop. For many decades the upper bound on addressable screen space (and data density) was the area of a book page, and the fineness of the plate that stamped ink onto the book.
When screens came along, designers had the chance to make video visualizations, allowed people to chart a progression of data over time, as in Hans Rosling’s famous chart of life expectancy and income over time.
Headsets Provide an Extra Dimension
With a headset you have the opportunity to actually provide and use 3D graphs, via the differing images presented to the left and right eyes. By manipulating the displayed objects over time, you can chart in four dimensions. This makes things like Ender’s view of the space battle (in the book/movie Ender’s Game) a possibility.
You could visualize Hans Rosling’s graph without needing to only show one year at a time. Imagine the circles in the graph stretched into tubes, all visible at once, making events like the Spanish Bird Flu or World War 2 immediately obvious as kinks in the tubes.
Headsets Provide More Screen Space
Because the screen on a headset moves when your head does, the addressable screen space becomes much larger. By my calculations, the Oculus Rift has roughly 230 dots per inch, or about 52,800 pixels per square inch. Assuming the data is presented on a half-sphere six inches away from your eyes, this yields 226 square inches of screen space, or 11 million possible pixels. By contrast, my 13 inch Macbook Pro, with the much higher DPI of the Retina Display, has only 4 million.
This means, in theory, that much more dense visuals should be possible with the Rift, especially if/when the screen becomes more densely packed with pixels as many expect.
Of course, there are additional considerations - the ideal place to put data is exactly in line with your eyes. But that doesn’t mean the areas above and below your eyeline cannot be used, especially when you can move your head. It will be exciting to see what sorts of data visualizations are made for headsets in our bold new virtual reality era.