Description
Often people will try to make charts look more interesting. Though this is a worthy effort, it can lead to graphics that emphasize interface verse information. Moreover, this effort can undermine the worth of data, which should be interesting enough. 3D effects is the most common technique, but should actually rarely be used. Only if the use of 3D will actually enhance your understanding of the data – not just make it cool and fun to explore – should it be considered. In most cases, the use of 3D can actually distort the information and make it more difficult to read and understand clearly.
Some situations where communicating information in 3D may be appropriate: the data dimension in fact exists within 3D space (geography), or for highly advanced scientific visualizations where the z-axis could show another variable. But again, before using 3D consider if it really does anything to actually enhance understanding. Just because something exists in 3D space doesn’t mean it’s most easily understood that way as a data visualization.
Examples
The chart below is attempting to show the difference between what people actually make (income) versus what they take on in debt in order to achieve the “American Dream.” However the use of 3D severely hinders a quick and easy understanding of the actual data. Without looking closely, it is difficult to compare the height of one bar to another, and the little figures on top of the bars certainly doesn’t do anything to help. You can’t even see the top of the home mortgage bar with the house on top of it. And what value do the figures add anyways? Without them, would you not understand what a mortgage is? Or what marriage is? Even the text is written in the 3D space on the bars, making that difficult to read as well. There is so much going on in this bar chart that is takes much more time to figure out than necessary.
The visualization by Time Magazine is showing population in the U.S. At quick glance, it is easy to see that New York City has the largest population (that is if that label were displayed – though is it on rollover). From there though, the comparisons become difficult. The question is whether this is more easy to understand that a standard flat map of the U.S. with cities/counties/etc colored by population. The other question is who is your audience and what information do they care about? If something general like what you can get from this map is all they want, then it would serve its purpose. If they are looking for more detailed information, this would not be the map for them.
The map below is from The New York Times and shows subprime mortgage foreclosures. Again, does the use of 3D enhance the understanding of the information? Considering it’s very difficult to see the differences in height, some 3D bars may be hiding other bars and the shadows from the bars make distinguishing the colors of the bars difficult, I’d say not. Perhaps a map like the 2 below would have been more effective. Maybe not as cool and eye-catching, but certainly it would show the data more clearly.
The chart from GOOD Magazine below shows the most frequently used words in two different books, but it is not effective. I believe it’s supposed to be a bar chart, but the use of 3D for the bars makes it impossible to accurately compare them. Without the numbers in the callout boxes, this chart would actually read incorrectly. For example, look at the two Bush bars. Without looking at the numbers in their callouts, they actually look the same when in fact they are not.
Related Principles
Minimize illusions
Communicate true scale
Use simplest appropriate visualizations