1

Symbology

The guts of making a

decent map!

2

What’s in the module?

• explore a GIS map and get information about map features

• preview geographic data and metadata• add data to a map• describe the structure of a GIS map• explain how a GIS represents real-world objects• change the way features are drawn on a map• access feature information in different ways• describe spatial relationships of map features• describe how GIS can be used to solve

problems

3

What is important in the module?

• explore a GIS map and get information about map features

• preview geographic data and metadata• add data to a map• describe the structure of a GIS map• explain how a GIS represents real-world objects• change the way features are drawn on a map• access feature information in different ways• describe spatial relationships of map features• describe how GIS can be used to solve

problems

4

And imbedded in there is …

• Information on how to decide…– what you want to communicate to

whom. – On the kind of classification to use to

do that

• That’s why you need to read the stuff in the text and think about what you are doing in module 2.

5

An Important Concept

• “Many Factors affect the colors you choose.

• The perceptual structuring of the colors should correspond with the logical structuring in the data…

• Make sure the character and organization of the colors match the logic of your data…”1

1 Cynthia Brewer, Designing better maps. ESRI Press

6

And…• “When choosing map colors

– you should not be overly concerned about which colors your audience likes. Everyone has an opinion …

– It does seem that most people like blue and do not like yellow.

– People like maps with many colors so focus your attention on presenting your data clearly using YOUR favorite colors.”1

1 Cynthia Brewer, Designing better maps. ESRI Press

7

And…• “When choosing map colors

– you should not be overly concerned about which colors your audience likes. Everyone has an opinion …

– It does seem that most people like blue and do not like yellow.

– People like maps with many colors so focus your attention on presenting your data clearly using YOUR favorite colors.”1

1 Cynthia Brewer, Designing better maps. ESRI Press

8

However

• Usually students don’t have to much trouble with making decent maps with reasonable symbolizations

• It comes naturally• But you do need to keep some

things straight when working with classifications of data

• And you usually have to classify

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Data Types• Nominal

– are categorical data where the order of the categories is arbitrary

• Ordinal– categorical data where there is a

logical ordering to the categories • Interval

– continuous data where differences are interpretable, but where there is no "natural" zero

• Ratio– continuous data where both differences and

ratios are interpretable

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….more• Quantitative data is numerical

– Ratio, Interval, ordinal data types– continuous data– you are not limited to acuity of the eye– depth-to-bedrock (ratio)– Water table, pollution conc.

• Qualitative data is not necessarily numeric– Nominal data – soil type, road classification– limited to max of 10-12 colors (classes) and

you want contrast – 5 is better yet

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Which on works better?

Depends on the purpose of the map

12

Symbols

• Lots of symbols for points, lines, & polys

• Labeling features – – Dynamic and Interactive– Annotation

• Symbolizing based on attribute– Category– Quantity

13

Quantity

• Graduated colors– Color ramps – which work best?

• Graduated Symbols (classification)

• Editing legend entries for the TOC

14

Classification

• How many classes• What method to use for placing the

values into classes• What kind of symbology to use

(e.g., graduated colors or graduated symbols)

15

Maps - Categorical

• Categorical symbolization is typically used for NOMINAL data– Quite often similar colors will be used

for related categories – You want the user to be able to

discern the categories

16

Quantitative maps

• Displays quantitative data – interval or ratio data and even ordinal data

• A graduated ramp or palette is used

17

Classifications

• Natural breaks : finds groupings inherent in the data. Default

• Equal interval : interval between each class is the same.

• Quantile : each class contains an equal number of values (features).

• Manual : you decide

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19

The Well Designed Map…

• Has a single purpose!• Size of paper and map scale determine

the level of detail• You cannot simply blow up a map from 8.5-11 to

something that would hang on the wall.• A small map size will limit detail• A large map viewed from a distance has same

problem

• Reader must be able to easily interpret features

• Reader should be able to instantaneously understand the maps message

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30000 0 30000 60000 Meters

N

EW

S

LEWIS COUNTYNEW YORK

%[%[%[%[%[%[%[%[%[%[%[%[ %[%[%[%[%[%[ %[%[%[%[%[%[%[%[%[%[%[%[ %[%[%[%[%[%[%[%[%[ %[%[%[

%[%[%[%[

%[%[%[

%[%[%[%[%[%[%[%[%[ %[%[%[%[%[%[%[%[%[%[%[%[%[%[%[%[%[%[

%[%[%[

%[%[%[

420000

420000

440000

440000

460000

460000

480000

480000

500000

500000

4820000 4820000

4840000 4840000

4860000 4860000

4880000 4880000

Rivers

%[ Sub Station

US Highway

State Highway

This map to be used to evaluate sites for future paper plant which has to be near a substation and a highway.

LAGIS, esf

No Placenames

ArcView Export screw up in 8.3!

Only went to 3000 m in Layout!

Too Much White Space!

21

The elements one-by-one

• Title– Draws attention by virtue of its size (big!)– Focuses attention on primary purpose of

content of map– Not always needed

• Legend– Principle reference to symbology– MUST be there (usually)

22

The elements one-by-one• Scale

– A MUST!– Types

• graphic -- the bar• verbal -- 1” = 1 mile (watch this one)• a ratio 1/24,000 (this one too)

– Because of ubiquitous nature of Xerox machines the graphic scale is a must, the others are optional

23

The elements one-by-one

• Credits– another, older, term for metadata– Some metadata can be placed on

map• Data source• Statement of accuracy, both spatial and

attribute• Date data collected, date map made• Your name, assignment # etc…

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The elements one-by-one

• Credits– another, older, term for metadata– Some metadata can be placed on

map• Data source• Statement of accuracy, both spatial and

attribute• Date data collected, date map made•Your name, assignment # etc…

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The elements one-by-one• Mapped and unmapped areas

– Objects, land, water, and other geographical features important to the purpose of the map

– makes the composition a map rather than a diagram

– The most prominent map element

• Graticule & Grids– Graticule – geographic coordinates

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The elements one-by-one

• Borders and neatlines– Borders serve to restrain eye movement

and focus attention on the map. A Border surrounds all the elements of a map.

– A fill color can substitue for a border– Neatlines are:

• finer than borders• drawn inside borders• mainly decoration• Used to highlight objects (like legends) and to

help balance a map

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Composition: Planar Organization

• Balance – visual impact of arrangement

• is the map “heavy” at top, bottom, sides???

Geometriccenter

Visual center:5% of total

height aboveGeometric center --

Arrange contentaround

this point

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Visual weight• Depends on location

– obj weight increases with distance from center

– obj at top are heavier than those at bottom– obj on right are heavier than those on left

• Depends on size (Duh!)• Depends on color, interest, and isolation

– Red>Blue, Bright>dark

– complex > simple– isolated > groups

• For Example …

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Which is better balanced?

30

Which is better balanced?

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Focus

Field

Movement of reader’s eye - upper left to lower right

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Using Eye Movement Eye goes left to right

Generally you want the reader to see the map BEFORE seeing the legend – can’t

always do it

33

•St. Louis too far from visual center, balance not bad, however•Hard to read name

Better, but a heavy on right

Balance with legend etc.

34

Location of St, Louis

Legend

-adf asdf

adfafffdsf

35

Location of St, Louis

Don’t really need

since countries

are labeled

36

Size / white space problems

Is this a better balanced map?

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Summary of Guidelines1) Map layout – where are the pieces going

to go – major pieces – visual center – eye path – uneven juxtaposition of parts

a) The map area and what’s in itb) Legend placement (usually to right of map)c) Scale bar, North Arrowd) Balancee) White space

2) Map Title – Large – may not be needed

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Summary of Guidelines3) Credits (Metadata) usually present4) For FOR357/557- Author’s name,

Exercise #, & date!5) Borders and neatlines.

a) Border around ALL map pieces or solid fillb) Neatlines (or fill) around (in) various

pieces

6) Color – tricky – but not garish!

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Booby Trap• When you make scale bar it is grayed

out?• Why• You didn’t set map and distance units• No map units then ArcGIS has no idea

what they are – probably no metadata• If map units are m and you don’t want

scale bar in meters then you have to set the distance units

40

Summary

• I have just covered the tip of the ice berg regarding symbols, color, and map design

• Even without intensive instruction in map design students tend to make decent designs

• Main problems are:– White space– Borders– Location of TOC