Midterm Flashcards
What are the three types of maps?
mental maps, virtual (computer), and real “cartographic” maps
What are the different types of maps based on use?
mental maps and maps based on collected data (charts/plans, general, and thematic)
what are different functions of maps?
navigation, visualization, and measurement
what are some advantages of maps?
more efficient than verbal descriptions, sources of data, and solve complex problems
what are some limitations of maps?
summary of selected facts about reality, selection depends on map scale, features may be generalized or simplified, may not be able to show full range of interest, and good maps are related to a specific use and focus on relevant information
what are some causes to the evolution of cartography?
printing press, compass, pendulum clock, aerial photographs, GPS, computer mapping, internet, and electronic datasets
what are 4 sources of error in cartographic communication?
map interpretation, data collection, cartographic abstraction and map design, and map reading and analysis
what do we need to know about the earth in order to make a map?
size, shape, and a common unit of measurement to describe location
what was Eratosthenes’ method for measuring the earth?
The sun is vertical at Syene at none on the summer solstice, but not in Alexandria, geometry says the distance between the two must be 1/50 of the circumference of the earth because of the angle of the sun in Syene, he measured the distance to be 5000 Stadia, and was 1-15% of actual circumference
what are some properties of map projections?
they all distort distances and angles and it is impossible to accurately represent all geometric relationships
what was the longitude problem and who solved it?
ships couldn’t measure longitude because they could not track time or use pendulums. It was solved by John Harrison in 1735 who developed extremely accurate clocks that worked at sea
what is Tissot’s Indicatrix (1859)?
It is using circles on a map to represent distortion
what is a gnomonic projection?
a perspective projection with a light source at center of generating globe, there is extreme distortion beyond 45 degrees from point of tangency, and it is useful for navigation
what is a stereographic projection?
a perspective projection with light source opposite of the point of tangency and can show more than a hemisphere, it is useful for radiating phenomena
what is an orthographic projection?
a perspective projection with light source an infinite distance from the globe, can show one hemisphere, and is essentially the view from space
