MAP SCALE

Scale varies across all maps

Pattern of scale distortion depends on map projection

Scale along line/point of SF = 1 (reference globe vs flat map) displayed in several ways:

Representative fraction, or simple scale1:100,000 or 1/100,000

Verbal statement – “One inch to 16 miles”

Bar Scale

Area Scale

REFERENCE SYSTEMS

Some common, familiar reference systems:

• Dewey Decimal system for libraries

• Street addresses used by postal service

• Road map grids used by Rand McNally, etc. on travel maps

• Zip Codes for area reference

• Area Codes used by phone company for area reference

COORDINATE SYSTEMS

Geographical coordinate system:

Older of two systems now in general use Uses latitude and longitude to locate positions on the uniformly curved surface of the earth Primary system – used for navigation and surveying

Rectangular/plane coordinate systems:

Used for locating positions on a flat map Evolved from cartesian coordinates applied to maps for for military purposes

COORDINATE SYSTEMS

Cartesian Coordinates:

Originally devised by armies for easier computation of artillery trajectories

Defined by origin and unit of distance – basically a graph

Depend on Euclidean geometry

COORDINATE SYSTEMS

Rectangular Coordinates:

o Based on Cartesian coordinate system

o Large scale maps typically use a conformal projection to maintain distance and direction calculations using rectangular coordinates

o False easting and northings are typically added to coordinate values to keep coordinates in the upper right hand quadrant of the ‘graph’ – positive values

o Most plane coordinate systems based on only these three conformal map projections: transverse Mercator, polar stereographic, Lambert’s conformal conic

o Not used for small scale maps – too much distortion

COORDINATE SYSTEMS

United States coordinate systems in common use:

• Universal Transverse Mercator Grid System

Topographic maps, satellite imagery, natural resourcedatabases, applications requiring precise positioning

Uses meter as basic unit of measure

Contains 60 narrow zones running N/S

SF constant only along NS meridian of each zone

Accurate overall to 1 part in 2500

COORDINATE SYSTEMS

United States coordinate systems in common use:

• Universal Polar Stereographic Grid System

Used to represent two circular polar zones not coveredby UTM system

SF is constant along parallels, which are circles inthis projection

Accurate overall to one part in 2500

COORDINATE SYSTEMS

United States coordinate systems in common use:

• State Plane Coordinate System

Devised in the 1930’s – plane rectangular coordinatesystem for each individual state

Based on transverse Mercator or Lambert’s conformalconic projections; line of constant SF depends onwhich projection used

Unit of measure is feet

Overall accuracy to one part in 10,000

COORDINATE SYSTEMS

United States coordinate systems in common use:

• Public Land Survey System

Basic unit is areal, not linear – acre

System is defined on the ground, not on a map grid

Currently covers ¾ of land in the 50 states

Baseline and meridian are defined on the ground andserve as origins

System defines township, range, section

Commonly used for legal descriptions of property

CARTOGRAPHIC DESIGN

Most design choices are compromises

Design as a process

Stage one – imagination, creativity, graphic ideation> decide on type of map, size and shape, basic layout, data to be represented, mapping technique, etc.

Stage two – specific graphic plan, most decisions made> kinds of symbolism, number of classes and class limits of data, color use, typographical relationships, line weights, etc. (often done on the fly using computers)

Stage three – detailed specifications> define all symbols and line weights, colors, lettering size, etc.

CARTOGRAPHIC DESIGN

• Design as a product

Does the map ‘look right’?

Should be clear, simple, uncomplicated, and elegant

Map should not look contrived

Map should be aesthetically pleasing, while at the same time being thought provoking

Does the map accurately and effectively communicate your message – the results of your data analysis?

WHO IS YOUR AUDIENCE?

CARTOGRAPHIC DESIGN

Basic Graphic Elements Point – position Line – direction and position Area – extent, direction, position

Primary Visual Variables Shape – regular/geometric or irregular/pictographic Size – length/height/area/volume – larger = more important Orientation – lines/elongated shapes – need reference Color (hue) – actual color (red, green, blue, etc.) Color (value) – tone or relative lightness/darkness

light = high value, dark = low value Color (chroma) – saturation/intensity/richness/purity

measured by how much gray is present

CARTOGRAPHIC DESIGN

From Robinson, Sixth Edition, page 320

The PrimaryVisual VariablesWith someExamples of theirSimple applicationTo the classes of symbols

CARTOGRAPHIC DESIGN

Types and symbols useful in quantitative mapping and their visual dimensions.

Courtesy JP Publications. From Dent, Fifth Edition, page 78.

CARTOGRAPHIC DESIGN

Secondary Visual Variables (pattern)

Arrangement – random or systematic shape and

configuration of component marks that make up a pattern

Texture – size and spacing of component marks that make

up a pattern

Orientation – direction arrangement of parallel rows of

marks or parallel lines that make up a pattern

CARTOGRAPHIC DESIGN

The Secondary Visual Variables with some examples of their simple application to the basicgraphic elements.

From Robinson, Sixth Edition, page 321

CARTOGRAPHIC DESIGN

Symbol Classes

Symbols should focus attention on what the symbol

represents, not what the symbol looks like

Point emphasizing symbols:

• Dots, triangles, pictographs

• Denote position, location of feature, intensity at a

place, representative location for spatial summary

• Examples: geographic coordinate location, radio

tower, spot height, centroid of area distribution,

conceptual volume (city population)

• Does not take up any geographical space

CARTOGRAPHIC DESIGN

Line Emphasizing Symbols

• Individual linear signs

• Depict rivers, roads, political boundaries

• Can also represent non-linear data such as

elevation/depth/volume – contour lines

• May or may not indicate actual geographical size of

features

CARTOGRAPHIC DESIGN

Area Emphasizing Symbols

• Indicate that region has some common attribute

• Examples include water, administrative jurisdiction,

soil type, other homogeneous measurable

characteristic

• Homogeneous nature depicted by even color or

uniform repetition of point or line symbols (pattern)

CARTOGRAPHIC DESIGN

Volume Emphasizing Symbols

• Represent vertical or intensity dimension of spatial

phenomenon through space

• Examples include terrain surfaces

• May be symbolized by color value (lightness)

variations, spot height data, profile or contour lines