Saw this a while ago and discussed with colleagues, whilst its a pretty cool rendering, mere probing accounts for a huge proportion of the traffic seen, and the location is almost useless as any attacker worth their salt with hide their location.
For example, although China does to a whole load of attacking, lots of the attackers in other Asian countries will try to use China as a staging node for their attacks, as they are then protected by China's "don't look or question anything we do" government policy. The same for Eastern Europe and Russia.
Similarly, lots of European attacks seem like they originate in the Netherlands, which is because that happens to be one of the major communication hubs for the EU.
The targets being mostly America is partly due to them being a major target, but it is also likely that its because that is where they have placed most of the honeypots.
Those "bombs" aren't DDOS either, its just the network receiving a bunch of delayed traffic from that particular IP. A DDOS attack would come from multiple sources and would be sustained.