Map of the Internetwp, 22 November 2003.
“This is our first full Internet map with color and other graphing logic.
RFC1918 addresses have been hashed into a unique checksum so they do not incorrectly overlap with other routers or hosts.”
The colors are based on Class A allocation of IP space to different registrars in the world:
- Asia Pacific – Red
- Europe/Middle East/Central Asia/Africa – Green
- North America – Blue
- Latin American and Caribbean – Yellow
- RFC1918 IPwp addresses – Cyan
- Unknown – White
Graph Engine: LGL (Large Graph Layout)
“Instead of mapping every single IP address on the Internet (theoretical maximum of 2^32=4,294,967,296 hosts) we simply traceroutewp to each class C network. The “traceroute” is a method to see how the operating Internet looks node-to-node. It’s more of a functional view than looking at how networks advertise over an ASNwp. This also reduces the theoretical maximum to 16,777,216 hosts.” 
Map 1069524880.LGL.2D.700×700.png from The Opte Project. Other images at higher resolution are available from the same location.
The Opte Project. The copyright date appears to be 2003.