What is a map? A map is a graphic representation of the whole or a part of an area. A map uses points, lines, and polygons to graphically represent an area. A map visually represents spatial relationships that exist in the real world.

World Map of the 2nd Century.

Introduction to Maps Definition A graphic depiction on a flat medium of all or part of a geographic realm in which real world features have been replaced with symbols in their correct spatial location at a reduced scale. Map: to transform information from one form to another --- Mathematics map Earth surface Paper The term “map” is often used in mathematics to convey the notion of transforming information from one form to another, just as cartographers transfer information from the surface of the Earth to a sheet of paper. The term “map” is used loosely to refer to any visual display of information. --- Geography The term “map” is often used in mathematics to convey the notion of transforming information from one form to another, just as cartographers transfer information from the surface of the Earth to a sheet of paper. The term “map” is used loosely to refer to any visual display of information.

Characteristics of Maps • Abstracted – requires careful interpretation • Often highly artistic Map making is as much an art as it is a science. • Show only static situation --- one slice in time • Usually out of date • Questions easy to answer by maps ○ how to get there from here? ○ what is at a certain location? • Questions difficult to answer by maps ○ what is the area of this lake? ○ what can I see from here?

The Transformation of Space The only true representation of the world is a globe.    Distortion occurs during transformation from 3-dimensional to 2-dimensional.    Map projections are used to minimize the distortion of certain features. The mapmaker uses a certain projection based on the purpose of the map.

Abstractions of Reality The real world is complex, so mapmakers generalize, simplify, and edit the type and amount of information presented on a map.    Therefore, maps portray only the information deemed necessary by the mapmaker to illustrate the purpose of a map.

Definition: a projection is a method by which the curved surface of Map Projections Definition: a projection is a method by which the curved surface of the Earth is represented on a flat surface. Locations on Paper Locations on Earth Surface Mathematical Transformation Note: There is always some sort of distortion distortion is small for maps showing only small areas, and greatest when a map attempts to show the entire surface of the Earth. Many projections invented, arguments continue on which is the best for which purposes

Large scale and small scale Map Scale Definition The scale of a map is ratio between distances on the map and the corresponding distances in the real world. Large scale and small scale a large scale map shows great detail, small features, e.g. 1:10,000 a small scale map shows only large features, e.g. 1:500,000 Scale Representation on the Map Representative fraction: 1:100,000, 1 to 100,000, or 1/100,000 Verbal: 1 inch = 50 miles Graphic: Scale bar 10 miles Note: map scale control not only how features are shown, but what features are shown a map of 1:1 is useless!!!

Scale and Fractions Why is a map of a big area called "small-scale" and a map of a smaller area called "large-scale"? Since map scales are expressed as ratios or fractions, 1:25,000 is a larger fraction of a whole than 1:1,000,000. So, how to understand these fractions? One mile = 5,280 feet, and one foot = 12 inches i.e., one mile = 63,360 inches Thus, 1:63,360 could mean that one inch on the map is one mile in the real world

The Effect of Scale on Area and Detail Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Effect of Scale on Area and Detail

Location and Attributes Maps are concerned with location.  Position in 2-dimensional space (i.e. x,y coordinates, latitude/longitude) Maps are concerned with attributes. Qualities or quantities, such as income or population Many relationships can be formed from location and attributes.

Location and Attributes: Relationships Relationships among locations where no attributes exist (Distance) Relationships among various attributes at one location (population, ethnicity, income) Relationships between locations and attributes (variation in income from place to place) Relationships between location of combined attributes (relation of income to education, as it varies from place to place)

Types of Map General purpose map dates back to centuries, and usually focus on topography. Today we call it topographic map,which shows a limited set of features, but including at the minimum information about elevations or landforms. Topography = shape of the surface More recently, a new type of map, called thematic map came into use in the last century. A thematic map shows the spatial patterns of a geographic theme, such as land use, climate, population etc.

Map Categories Planimetric Maps Topographic Maps Thematic Maps Cartograms Remotely sensed images

Planimetric Maps Planimetric maps do not show relief features (e.g. elevation) Planimetric base maps are used to provide the framework for thematic maps (which present information about some special subject)

Topographic Maps Maps that show shape and elevation of terrain are called topographic maps Ex: Engineering maps, flood-prone area maps, landscape maps, etc.

Topographic Map of Santa Barbara, California Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Topographic Map of Santa Barbara, California U.S. Geological Survey

Thematic Maps Show information about special topics superimposed on a base map Types of thematic maps include geologic, forestry, soil, land-use, slope, and historical

Thematic map example

Cartograms Cartograms are created by substituting a different standard of measurement (time or cost, for example) for the distance measurements customarily used. This modifies size, shapes, and distances The following cartogram shows the election results, by county, and red, blue, and shades of purple to indicate percentages of voters

Cartogram

Title Neatline Labels Legend North Arrow Author, Source Scale

Maps Lie Mapmaking is an art form as well as a science, so it is subjective. Maps are simplifications, or models, of the real world. Often, what is not shown is more important than what is shown on a map. Therefore, all maps lie to some degree. When one is using maps, it must be known that biases can exist and interpretations must be tread carefully upon.