Geography: Methods and Materials Lecture 1: True Maps, False Impressions  Describe basic characteristics of maps,  Describe various ways landscapes are portrayed

I. The Nature of Maps A.Map A.Map : two dimensional representation of the spatial distribution of selected phenomena... indispensable B.Basic attributes of maps, making them indispensable:  Their ability to show distance, direction, size, and shape in two dimensional spatial relationships  They depict graphically what is where and are helpful in providing clues as to why such a distribution occurs. map C.Basic fault of a map?  No map can be perfectly accurate, why?  Maps are trying to portray the impossible – taking a curved surface and drawing it on a flat piece of paper scale D.The matter of scale  Gives relationship between length measured on map & corresponding distance on the ground, essential for being able to measure distance, determine area, and compare sizes.  Scale can never be perfectly accurate (Earth’s curved surface) o Smaller area being mapped, the more accurate the scale…

Location  Location a)Absolute location (grid system)grid system latitude / parallel lines longitude / meridians b) Relative location Relative

E.Scale types  Several ways to portray scale, but only 3 widely used: 1. Graphic 1. Graphic scale: a. uses a line marked out in graduated distances b. Remains correct when reproduced in other sizes 2. Word 2. Word scale: a. also called verbal scale; uses words to give the ratio of map scale to actual distance 3. Fractional 3. Fractional scale: a. Uses a ratio or fraction, called a representative fraction, to express the comparison of map distance with ground distance b. Scale 1/63,360 is commonly used; 1 in = 1 mile c. Can use any units for the ratio I. The Nature of Maps

F.Large and small scale 1.The concepts of large and small are comparative, not absolute, it all depends on the frame of reference. 2.Large-scale 2.Large-scale map – has a relatively large representative fraction; denominator is small 3.Small-scale 3.Small-scale map – has a small representative fraction, the denominator is large a. Portrays large portion of Earth’s surface, but gives limited detail. I. The Nature of Maps

A.Globes have several advantages: 1. Can maintain correct geometric relationships of meridian to parallel, of equator to pole, of continents to oceans, 2. Can show comparative distances, comparative sizes & accurate directions, 3. Can represent without distortion the spatial relationships of features on Earth’s surface. II. The Role of Globes

Globe properties  Parallels  Parallels of latitude  parallel to each other  decrease in length closer to the poles  Meridians  Meridians of longitude  converge at the poles  equal length (1/2 equator) Both: intersect at right angles

World from Space

III. Map Projections A.Process of transferring the spherical earth onto a 2-dimensional surface. B.Estimate size and shape of earth in 3 dimensions C.Properties of map projections: equal area (area) conformal (shape) equidistant (distance) azimuthal (direction) D.Types of map projections: cylindrical conic azimuthal (planar)

III. Map Projections E.Major problem: Equivalency vs. Conformality 1.Central problem in choosing a projection? a) Impossible to perfectly portray size & shape so compromise between Equivalency & Conformality 1)Equivalence: property of map projection that maintains equal area relationship 2)Conformality: property of map projection that maintains proper angular relationships b) Can only approximate Equivalency & Conformality in maps of of very small areas (large scale maps) 1)Map making is art of compromise (Robinson projection) 2.Equivalent projection: equal area: a) Disadvantage: small scale maps display disfigured shapes 3.Conformal projection: equal shape: a) Disadvantage: distort size – larger sizes in high latitudes

III. Map Projections

Mercator projection

Transverse Mercator

Albers conic (equal area)

Azimuthal

Peters projection (equal area)

Robinson projection

Projections: Implications  Projection should suit the application: Direction important? Conformal Comparing areas? Equivalent

A.Computer technology has provided several great benefits to cartography: Improved speed and data handling ability, Reduced time involved in map production, Ability for cartographer to examine alternative maps layout. IV. Automated Cartography

A.Satellite system for determining accurate positions on Earth’ surface. 24 satellites transmit position information (clocks) Most GIS accurate to about 30 feet Used in earthquake prediction, ocean floor mapping, volcano monitoring, and mapping projects. Global Positioning System

VII. Geographic Information Systems GIS is an abbreviation for G eographic I nformation S ystem, which are... automated systems for the capture, storage, retrieval, analysis, and display of spatial data, or computer mapping & analysis of geographic data Links tabular data to maps

GIS involves working with layers of spatial data superimposed on one another

What Are the Components of a GIS? Hardware Software Data Methods People

VIII. Remote Sensing A. Study of the Earth’s surface from a distance 1. recording instruments operating from high altitude a) Different kinds of remote sensing 1) Aerial photos, color & infrared sensing, thermal infrared sensing, microwave, SPOT B. Aerial Photographs 1. First form of remote sensing 2. Aerial photograph: photo taken from elevated platform such as balloon, rocket, airplane, satellite a) Either oblique or vertical 1) Oblique: Angle less than 90 degrees 2) Vertical: camera angle perpendicular a) photogrammetry

VIII. Remote Sensing C.Orthophoto Maps 1. Multicolored distortion free photographic maps produced from computerized rectification of aerial imagery. a) Landscape in detail b) Precise measurement of distance, shows subtle topographic detail D.Color infrared 1. Color – visible light region of EM spectrum a) Evaluate health of crops & trees b) Landsat – satellites image Earth every 9 days