A chart like this could really make sense if you want to visualise multiple factors. Example: sales figures for visitors to a webshop, sorted by country of origin. In that case the circle parts could represent the country of origin, the height of the parts the average amount paid and the volume of each part would represent the total amount of sales to that particular country.

Please ignore the overly pretentious ones who claim that it distorts anything.

A piechart’s role is to convey an approximate area, it does not matter if it is slightly distorted. One only cares about whether the areas are about equal, twice as big etc.

The image is gorgeous. There is a market for gorgeous stuff. Otherwise we all be using gnuplot … yikes.

But as far as charting libraries go, you’ll need to have a large number of them, plus customization. It is a tough project.

Even without the 3D foreshortening, pie charts are considered “low density and fail to order values along a visual dimension.” Distorting them with 3D, shadows, reflections, height differences, etc. just obscure the information worse.

You might want to read Edward Tufte’s books, or the “Ask E.T” forum:
http://www.edwardtufte.com/bboard/q-and-a?topic_id=1

Nick, granted a 3D pie chart makes it a little harder to determin relative proportions than a 2D one, but I don’t think they are useless — people are used to viewing real world objects with foreshortening. I’m also looking in to ways of displaying the actual percentages over the pie chart…