A map is a way of representing on a two-dimensional surface, (a paper, a computer monitor, etc.) any real-world location or object. Many maps only deal with the two-dimensional location of an object without taking into account its elevation. Topographic maps / aerial maps on the other hand do deal with the third dimension by using contour lines to show elevation change on the surface of the earth, (or below the surface of the ocean).
General vs. Thematic cartography
- In understanding basic maps, the field of cartography can be divided into two general categories: general cartography and thematic cartography / aerial maps.
-General cartography involves those maps that are constructed for a general audience and thus contain a variety of features. General maps exhibit many reference and location systems and often are produced in a series.
-For example, the 1:24,000 scale topographic maps of the United States Geological Survey (USGS) are a standard as compared to the 1:50,000 scale Canadian maps.
-Thematic cartography aerial maps involves maps of specific geographic themes, oriented toward specific audiences.
-A couple of examples might be a dot map showing corn production in Indiana or a shaded area map of Ohio counties, divided into numerical choropleth classes.
-An orienteering map combines both general and thematic cartography, designed for a very specific user community.