Friday 17 April 2009

Virtual Globes are a good idea for thematic mapping

It's important to seriously discuss and measure the quality of different thematic mapping techniques. I appreciate the critique from Dr. Mark Harrower on the Axis Maps Blog. I encourage everyone to read Mark's blog post - it's an interesting and timely read. This is a quick response to this critique - more blog posts will follow.

In short, I agree with most of the arguments put forward, but I disagree with the conclusions:
  1. I agree that my 3-D graduated symbol maps are "pure chart junk", but there are some good examples of 3-D symbol maps. (See previous blog post)

  2. I disagree that 3-D prism maps are chart junk - but thematic world maps on a 3-D globe are problematic. (See previous blog posts: [1], [2], [3]).

  3. I very much disagree that Virtual Globes are a bad idea for thematic mapping, but it's certainly not the only or the ultimate way of showing thematic maps.
I hope more people will engage in this important debate. What is your opinion about 3-D visualisations?

Update 28 April: This issue is currently debated on Axis Maps Blog, Google Earth Design and PTS Blog.  


Mark Harrower said...

Hi BJØRN - Thanks for getting the discussion going about thematic maps in virtual globes with your work (and here in your blog). I agree we need to have a good discussion about these emerging mapping techniques. The work you're doing simply could not have happened a mere 5 years ago, and when the cartographic landscape changes this quickly, it's especially important to explore, debate, and study all of these new mapping opportunities (all of which is healthy for cartography). Cheers!

Juan Lucas Domínguez said...

Hello. The thematic maps with phones are really cool, but the map showing countries as prisms is wrong. The height of each country must be proportional to population density, not to overall population. Regards

Bjørn Sandvik said...

There are two new blog posts commenting this discussion.

Rich Treves mostly agrees with Mark, but has a partial defense of 3D thematic maps.

Jon Peltier argues that a side by side map and bar chart are more effective than a prism map.

I've added a few clarifications to Jon's blog post:

"Bjørn assures us that the dome shape allows people to judge their volumes."

Wrong. I'm only saying that the volume of each symbol are calculated according to a statistical value. I do acknowledge that people are not particularly good at estimating volumes, especially when seen in perspective. It’s one degree harder for the viewer to assess the relative size of 3-dimensional symbols compared to 2-dimensional, which again is harder to compare to 1-dimensional.

"Bjørn reminds us that the 3D prisms make country comparison easier when spinning the globe."

Wrong. I've said that the ability to compare all countries is lost when thematic maps are rendered on a globe, while discussing various ways to address this issue.

Anonymous said...

I'd like to see more attention paid to the audience in this debate. So far, I've seen the opinions of a bunch of map producers, but I haven't seen the opinions of any map consumers. The idea behind a map is to convey information. Exactly how that information is consumed is beyond the control of the producer. Will your intended audience 'get it'? You never really know. If you do manage to get your point across, though, then whatever tools you used to do so are necessarily the right tools for the job, irregardless of their inherent precision.

Ray J. said...

I think that thematic maps is quite cool. No problem with that at all. However, I do agree with Juan Lucas Dominguez about the maps showing countries as prisms. This seems wrong to me also. - Ray J.