Map Projections and Types

Cartography The art and science of making maps, including

data compilation, layout, and design. Also concerned with the interpretation of

mapped patterns.

A stone tablet found in a cave in Abauntz in the Navarra region of

northern Spain is believed to contain the earliest known

representation of a landscape.

Maps

Visual representation of the earth’s surface or the phenomenon (any observable occurrence) that occur on the earth’s surface.

Map Scale The degree to which a map “zooms in” on the

area it is representing.

Scale tells you what extent the portion of the earth represented on the map has been reduced from its original size to fit on the map.

For example, 1 inch on a map may equal 10 miles in the real world. That scale might be written as 1 inch = 10 miles.

Sometimes, scale is indicated as a fraction. “1/10 miles” or “1:10 miles” means 1 inch on the

map equals 10 miles in the real world.

THIS IS THE TRICKY PART Counterintuitive part of mapping:

“LARGE” OR “SMALL” scale. The more “zoomed in” the map is on an area, the

larger is its map scale. large-scale map depicts a smaller area

The less “zoomed in” the map is on an area, the smaller is its scale. Small-scale map depicts a larger area

Map Projections

Earth is

ROUND!

So? Transforming something spherical into

something flat means that the 2-D image will never exactly represent what is visible in three-dimensions.

Geographers use numerous mathematical equations to produce map projections.

All flat maps have some distortion in their representation of: Distance Shape Area Or direction.

Types of Projections Equal-area (or equivalent) projections: maps

that maintain area but distort other properties.

Conformal (or orthomorphic) projections: maps that maintain shape but distort other properties (it is impossible to have a projection that is both conformal and equal area).

Azimuthal projections: maps that maintain direction but distort other properties.

Equidistant projections: maps that maintain distance but distort other properties.

Mercator Projection Cylindrical map projection Useful for navigation because it maintains

accurate direction Famous for their distortion in area that makes

landmasses at the poles appear oversized

Mercator Projection

Peters Projection Cylindrical map projection Attempts to retain all the accurate sizes of all

the world’s landmasses Sometimes used as a political statement- that

we should refocus our attention to the tropics, home to large landmasses and many of the world’s poorest countries.

Peters Projection

Fuller Projection Maintains the accurate size and shape of

landmasses Completely rearranges direction such that the

four cardinal directions (north, south, east, and west) no longer have any meaning.

Fuller Projection

Robinson Projection Attempts to balance several possible

projection errors. Does not maintain completely accurate area,

shape, distance, or direction, but it minimizes errors in each.

Used by National Geographic

Robinson Projection

Azimuthal Projection Planar

Formed when a flat piece of paper is placed on top of the globe and, as described earlier, a light source projects the surrounding areas onto the map.

Either the North Pole or South Pole is oriented at the center of the map which gives the viewer the impression of looking up or down at the earth.

Azimuthal Projection

Map Types

Reference Map

Show locations of places and geographic features.

Thematic Map

Tell a story about the degree of an attribute, the pattern of its distribution, or its movement.

Thematic Map

Contour Maps (Isopleths)

Isolines- Lines on a map depicting areas of same or like values.

Contour maps use isolines, or contour lines, to depict where the same elevation exists.

The contour interval of a contour map is the difference in elevation between successive contour lines.

Contour Maps

Proportional Symbols Map The proportional symbol technique uses

symbols of different sizes to represent data associated with different areas or locations within the map.

Proportional Symbols Map

Proportional Symbols Map

A dot may be used to locate each occurrence of a phenomenon.

Where appropriate, a dot may indicate any number of entities, for example, one dot for every 100 voters.

Dot Map

Military families in Ohio

Choropleth Map Shows statistical data aggregated over

predefined regions, such as counties or states, by coloring or shading these regions.

For example, countries with higher rates of infant mortality might appear darker on a choropleth map.

Choropleth Map

Cartogram A cartogram is a map in which some

thematic mapping variable is substituted for land area or distance.

The geometry or space of the map is distorted in order to convey the information of this alternate variable.

Cartogram

Cartogram

Cartogram

GIS map A geographic information system (GIS)

integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.

GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.

GIS map

GIS Map

Location Chart

Visualizations

Visualizations

Cognitive Map Mental map.

Map drawn from memory.