If you grew up playing video games in the 80’s, you’ll have fond memories of Pac-Man and Ms. Pac-Man. These classic arcade games were revolutionary in their day and continue to be favorites today. If you compare their simple 2D format to today’s lifelike first-person shooters, you wonder why people still continue to play them. The fact is their simple game play is still infectious.
Over the years, I’ve seen several lame variations of Pac-Man. In order to add sizzle to the Pac-Man theme, some game developers have tried to add a 3D perspective to the traditional 2D game — but with limited success. They took something simple and fun, and transformed it into yellow 3D crap.
I’ve seen a similar practice with charts in PowerPoint. In hopes of making a chart more stylish or impactful, presenters may add a 3D perspective to their charts. Using 2D charts all the time can be repetitive and maybe even boring. I’ve shared how you can add a nice bevel effect to your 3D pie charts in PowerPoint 2007. However, I was recently reminded why you need to be careful with 3D charts.
Someone recently asked me what was going wrong with a 3D pie chart in one of their PowerPoint presentations. Although Japan and South Korea represented 37% and 27% respectively, S. Korea looked larger than Japan (see 3D chart on left).
After examining what was going wrong, I identified that the 3D perspective was the culprit. Due to S. Korea being in the foreground, it deceptively appeared larger than Japan which was at the back of 3D pie chart. In the graph above, you can see how the 2D pie chart on the right more clearly reveals the true size differences between the various data points. If you absolutely have to use a 3D pie chart, I strongly recommend labeling the slices so that your audience can more easily interpret the data.
3D chart problems are not isolated to just pie charts. Bar charts can be difficult to interpret when a 3D perspective is used, especially the more extreme the 3D effect. When the 3D bar chart’s axis is angled or skewed, it becomes more difficult to compare data points and requires “value” labels in order to be usable.
When you’re debating between 2D or 3D charts, try to remember your audience. No matter how “pretty” your charts look, they need to be easily interpreted. Just like Pac-Man, it is never a bad idea to just keep things simple. If you’re interested in more information on this topic, Garr Reynolds of Presentation Zen fame has an interesting post on 2D and 3D charts.