Denis Cosgrove, in his book , presents two techniques of evaluating or reading maps: its final form and the mapping processes used. From both, we can extract useful information to critically read maps. In regards to mapping processes, he talks about the evolution of techniques and instruments in addition to sight and body senses such as photographs and use of balloons. But securing the truth of map surveying from the place of survey to place of compilation could be challeging. This idea makes me think of techniques of survey being used nowadays. When we read maps, we usually do not think of how that type of information was extracted, how the cartographer implemented into spatial maps. Compilation of these information, as it was mentioned in the book, is made of arbitrary decisions.
J.B. Harley adds an interesting layer to the conversation in terms of the symbology of maps. Maps as articulated objects, highly defined by the context in which they were produced. State, for instance, has always used maps to express power or influence over its people. Still nowadays, the ways maps are drawn can work as a tool of influence.
Coincidentally, I was reading an article that talked about how some areas in the coast of Spain are shown blurry in google earth. There has been illegal construction along the coast of Spain, mostly tourism development privatizing waterfront, violating the law. It exposes new questions, since today one of the most important public accessible maps is google earth.