Don’t use ‘em…

…Unless you have multidimensional data that requires 3 points of definition (even then it’s a risky idea).

3-D charts create perspective by tricking the eyes and these tricks skew users’ perception of the data.

Even multidimensional data doesn’t necessarily need a psuedo-3D or 3D rendering. The archetype being Minard’s chart of Napoleon’s march on Moscow. Each point in the plot has at least four (x and y location on a 2-D plane, direction of travel, and size of the army) dimensions and some (the retreat) include time and temperature. No fancy 3-D here and yet, it’s probably the best chart ever made (I happen to whole heartedly agree with Tufte on this one).

It has been my experience that, especially in business, 3-D charts are a gimic - they offer a quick hit of supposed professionalism or ‘design esthetic’ to a chart. They are very tempting because the software authors put some more design work into them than they did the other chart types. But at what cost? If the slickly designed chart skews understanding, doesn’t that potentially lead to the wrong decision and the wrong action?

So watch out for 3-D charts, they don’t typically add any value or better portray the information you are trying to convey and, in the worst case, can be harmful to the decision-making process.