What did renaissance map makers base their maps on

The maps they drew were based on explorer observations and mathematical calculations. The ancient Greek maps are important to the history of cartography because they often showed Greece as being at the center of the world and surrounded by an ocean.

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.