I don't think that graphic you're thinking of shows "world GDP" so much as "the centre of gravity of GDP across the planet": These are two quite different things. In any case, you might have in mind a map by McKinsey Global Institute in their "Urban World" 2012 report.
I'd disagree that that depiction was better designed than http://www.dannyquah.com/Quilled/Output/2010.09.27-Danny.Qua... or the animation http://www.dannyquah.com/Quilled/Output/2010.08-Danny.Quah-w... It depends on what you're trying to understand. For what you describe, I personally don't like so much the McKinsey graphic. This is discussed in Section 8.3 (in Chapter 8) of my draft manuscript http://bit.ly/1KeSicU on Ordering the World.