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fandomhigh2005-10-28 08:56 pm
notjustacabbie.livejournal.com) wrote in fandomhigh2005-10-28 08:56 pm
Physical Geography #2
After covering the underlying structure it's time to look at mapping the surface of the Earth.
Cartography or mapmaking is the study and practice of making maps or globes. Maps function as visualization tools for spatial data. Spatial data is acquired from measurement and can be stored in a database, from which information can be extracted for a variety of purposes. The cartographic process rests on the premise that there is an objective reality and that we can make reliable representations of that reality by adding levels of abstraction.
Because of the infinite nature of our Universe it is impossible to capture all of the complexity found in the real world. For example, topographic maps abstract the three-dimensional real world at a reduced scale on a two-dimensional plane of paper.
More specifically the type of map projections chosen affects the distortion.
Conformality - When the scale of a map at any point on the map is the same in any direction, the projection is conformal. Meridians (lines of longitude) and parallels (lines of latitude) intersect at right angles. Shape is preserved locally on conformal maps.
Distance - A map is equidistant when it portrays distances from the center of the projection to any other place on the map.
Direction - A map preserves direction when azimuths (angles from a point on a line to another point) are portrayed correctly in all directions.
Scale - Scale is the relationship between a distance portrayed on a map and the same distance on the Earth.
Area - When a map portrays areas over the entire map so that all mapped areas have the same proportional relationship to the areas on the Earth that they represent, the map is an equal-area map.
Discussion/Homework: In what situations would projections be a valid choice? This may be a helpful source.
Cartography or mapmaking is the study and practice of making maps or globes. Maps function as visualization tools for spatial data. Spatial data is acquired from measurement and can be stored in a database, from which information can be extracted for a variety of purposes. The cartographic process rests on the premise that there is an objective reality and that we can make reliable representations of that reality by adding levels of abstraction.
Because of the infinite nature of our Universe it is impossible to capture all of the complexity found in the real world. For example, topographic maps abstract the three-dimensional real world at a reduced scale on a two-dimensional plane of paper.
More specifically the type of map projections chosen affects the distortion.
Conformality - When the scale of a map at any point on the map is the same in any direction, the projection is conformal. Meridians (lines of longitude) and parallels (lines of latitude) intersect at right angles. Shape is preserved locally on conformal maps.
Distance - A map is equidistant when it portrays distances from the center of the projection to any other place on the map.
Direction - A map preserves direction when azimuths (angles from a point on a line to another point) are portrayed correctly in all directions.
Scale - Scale is the relationship between a distance portrayed on a map and the same distance on the Earth.
Area - When a map portrays areas over the entire map so that all mapped areas have the same proportional relationship to the areas on the Earth that they represent, the map is an equal-area map.
Discussion/Homework: In what situations would projections be a valid choice? This may be a helpful source.