History of Cartography,

Transcription

1 Maps

2 History of Cartography, the art and science of making maps ~2300 BC ~600 BC Early oldest known maps: Babylonian clay tablets. Greek and Roman Ptolemy s (about AD ) "world map" depicted the Old World from about 60 N to 30 S latitudes.

3 History of Cartography, the art and science of making maps Medieval T-O maps were dominated by religious views. Before 15 th century, maps were hand drawn which made their distribution extremely limited. 12 th century Isidore 11 th century Hereford ~1280 Psalter 13 th century

4 History of Cartography Renaissance maps: beginning in the 15 th century, the invention of printing made maps much more widely available. First whole-world maps began to appear in the early 16 th century following voyages by Columbus and others to the New World. Henricus Hondius, 1633 First map to use the name America to label the New World, ~1507

5 From Globe to Map A map is a graphic representation of geographic information on a flat surface. Transferring information from the spherical, or ball-shaped, surface of Earth onto a flat piece of paper is called projection. A globe, a spherical model of Earth, accurately represents the shapes and locations of the continents. What about a map?

6 Map Projections Projection is a major challenge for cartographers. Every map has some sort of distortion: it can retain either the correct sizes of landmasses or the correct shapes of very small areas, but not both. Cylindrical (Mercator): projection onto a tube that is wrapped around the globe and touches it along one line, most often the Equator (the regions near the Equator are the most accurate, regions near the poles are the most distorted).

7 Distance and Direction In navigation, a rhumb line (loxodrome) is a path with constant bearing (constant course) as measured relative to true or magnetic north; it is an arc crossing all meridians of longitude at the same angle. Early navigators in the time before the invention of the marine chronometer used rhumb line courses on long ocean passages, because the ship's latitude could be established accurately by sightings of the Sun or stars but there was no accurate way to determine the longitude. On a Mercator projection map, a rhumb line is a straight line, which makes this projection uniquely suited to marine navigation.

8 1679 Mercator Map of the World

9 Distance and Direction A great circle is the path of shortest distance between two points on the surface of a sphere (globe). Long distance air travel great circle route is often used. The difference between great circle course and rhumb line course is most dramatic near the Poles.

10 Map Projections Conical: projection on a flattened cone, with curved lines of latitude and straight meridians (great for mapping mid-latitudes, for example the US Map). Planar: projection onto a plane with a single point of contact (most accurate at that point; often used for maps of one of the poles). Interrupted: "orange-peel map" equal-area projection (preserves area measure, generally distorting shapes). Winkel-Tripel: compromise projection, minimizes three kinds of distortion: area, direction and distance.

11 Purpose: General (variety of features for a general audience) Thematic (specific geographic themes) Detail level: Topographic (detailed and accurate; large-scale detail and quantitative representation of relief using contour lines) Geographic Map Geographic maps can be classified into categories by: Topological (simplified so that only vital information remains; lack of true scale, distance and direction) NY City Subway Map

12 The elevation of a geographic location is its height above (or below) a fixed reference point, most commonly the Earth's sea level. The term elevation is mainly used when referring to points on the Earth's surface. Altitude is used for points above the surface (an aircraft in flight or a spacecraft in orbit). Depth is used for points below the surface. Mapping Elevation

13 Types of Maps Physical Political

14 The Fool s Cap World Map Are maps realistic representations of the actual world? Not really! A map can display only a few selected features, usually in highly symbolic styles. All maps are estimations, generalizations, and interpretations of true geographic conditions, made according to certain basic assumptions which are not always true or verifiable.

15 United States Geological Survey The United States Geological Survey (USGS) is a scientific agency of the United States government (Department of the Interior). The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. As a part of its mission, the USGS produces several national series of topographic maps which vary in scale and extent: before 2008, traditional methods of surveying, revising, and updating topographic maps were used (aerial photography and field checks) currently most maps are mass-produced using automated and semiautomated processes, with cartographic content supplied from the National GIS (Geospatial Information Science) Database; while much less expensive to compile and produce (as only about two hours of interactive work are spent on each map with essentially no field checks), the revised digital U.S. topo maps have been criticized for a lack of accuracy and detail in comparison to older generation maps.