quote 01:00:05 Due to the satellite constellation in the UK, a large void exists from the zenith to the horizon in a northerly direction. This lack of GPS satellites results in poor satellite geometry in the north-south direction.
GPS measurements on the London Millennium Bridge, from a 2006 article in the Institute of Civil Engineers’ Proceedings on Bridge Engineering.
quote 20:16:11 As the mental maps of each of the islands grew, they started to merge together and the islands of London metaphor began to gradually fade away. Eventually, I switched to a small shirt-pocket sized map of inner London and left my islands of London map book at the hotel.
quote 17:46:32 Due to sensitivities over government and military installations, only 11 companies in China have licenses to do comprehensive mapping, and half of those simply exist to support the government.
quote 22:02:00 London above ground is a terrifically complex and chaotic entity with few visible principles of organization. London under ground, in contrast, has been represented for over seventy years as an organized, understandable and navigable city, by paying no mind to the city’s actual, unmanageable geography.
Janet Vertesi in Mind The Gap: The ‘Tube Map’ as London’s User Interface (PDF). The whole thing is well worth a read. (Hat tip: the Human Transit blog.)