1. Representations of the Earth Maps, GIS and Remote Sensing

2. Tools of the Geographer Maps A map is the fundamental tool of the geographer. With a map, one can illustrate the spatial distribution (i.e., geographic pattern) of almost any kind of phenomena. Maps provide a wealth of information. The information collected to create a map is called spatial data. Cartography is the art of map making

3. Projections—From a Sphere to Flat Maps ÔProjections are created by transferring points on the earth onto a flat surface. You can think of this as having a light in the middle of the earth, shining through the earth’s surface, onto the projection surface. There are three basic methods for doing this: ÔCylindrical--projection surface wrapped around the Earth; point of contact is equator ÔConformal projection (‘preserves’ shape of continents at equator only) ÔPlanar--projection surface is a ‘flat’ surface against the Earth at a particular latitude or longitude ÔNeither Conformal or Equal Area ÔDoes not ‘preserve’ shape of continents nor provide measure for equal area ÔConic–- projection surface is a cone is placed on or through the surface of the Earth ÔWhere the projection surface touches the Earth is the “Standard Line.” ÔCan be either Conformal or Equal Area

4. Trouble with Projections ÔDistortion--It is impossible to flatten a round object without distortion. ÔProjections try to preserve one or more of the following properties: ÔArea--sometimes referred to as equal area (for small areas) ÔProjections that preserve ‘area’ are referred to as “Equal Area” projections ÔShape--usually referred to as “conformality”, again for small sections ÔProjections that preserve “shape” are referred to as “Conformal” projections ÔDirection--or “azimuthality” - cardinal directions (N,S,E,W)

5. PROJECTION CHALLENGES zConformality xMeridians (lines of longitude) and parallels (lines of latitude) intersect at right angles. x Shape is preserved locally on conformal maps. zArea yWhen 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. zCONFORMAL VS EQUAL AREA: Projections can be either conformal or equal area – but not both!

6. Projections--Cylindrical Projection Point of contact at equator

7. Projections--”Developing” a Cylindrical Projection

8. Cylindrical Projection: A Conformal Projection Note increasing distance between lines of latitude….why?

9. Why Mercator? NAVIGATION !! zIn a Mercator projection, the lines of longitude are straight vertical lines equi-distance apart at all latitudes, and horizontal distances are stretched above and below the equator. zMercator’s projection preserves exactly what sailors in the 16 th century needed -- shapes and directions; they were very willing to accept the size distortion.

10. Projections--Polar Planar Projection

11. Polar Planar Projection Projection centered on North Pole

12. Projections--Conic Projection

13. Conic Conformal Projection

14. CONIC PROJECTIONS zA better choice for mapping regions such as the United States is a conic projection, which projects shapes from the Earth’s sphere onto a cone. zLocations near the line where the cone is tangent to the Earth will be relatively free of distortion

17. MAP SCALE zMap Scale is the ratio of the distance between two points on the Earth’s surface and the distances between corresponding points on a map zThere are several types of map scales: yVerbal Scale: 1 inch = 1 mile yBar Scale: a graph depicting distances yRepresentative Fraction: xOne unit of measured distance on a map equal some units of measured distance in the real world

18. REPRESENTATIVE FRACTION zRepresentative Fraction (RF) is the ratio between measured distances on a map and measured distances on the Earth’s surface. zRF is a unitless measure – but, both sides of the ratio must be identical units zA RF scale expressed as a ratio of 1:25,000 means that one unit measured on the map represents 25,000 units on the ground. y1 inch measured on a map represents 25,000 inches on the Earth’s Surface or… y1 cm measured on a map represents 25,000 centimeters on the Earth’s surface.

19. LARGE-SCALE VS SMALL-SCALE zLarge-Scale Maps show very small portions of the real world, but with great detail. yLarge-Scale maps have small denominators i.e., 1:12,000 or 1:10,000 yTopographic maps are examples of large-scale maps zSmall-Scale maps show very large portions of the real world, but with minimal detail ySmall-scale maps have large denominators, i.e., 1:100,000 or 1:1,000,000 yWall maps are examples of small-scale maps

20. LARGE SCALE TO SMALL SCALE LARGE SCALE SMALL SCALE

21. Topographic Maps

22. 3-D Topographic Maps

23. Thematic maps are used to communicate geographic concepts like the distribution of densities, spatial relationships, magnitudes, movements etc. World climate or soils maps are notable examples of thematic maps. Thematic maps show population density as colored polygons and the distribution of major earthquakes felt throughout the country. Graduated circles indicate the area over which the earthquakes were felt.

24. Thematic Maps: Temperature Maps

25. Ethnicity Maps

26. Precipitation Maps

27. Population Maps