1 symbology the guts of making a decent map!. 2 what’s in the module? explore a gis map and get...
TRANSCRIPT
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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
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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
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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.
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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
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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
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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
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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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Symbols
• Lots of symbols for points, lines, & polys
• Labeling features – – Dynamic and Interactive– Annotation
• Symbolizing based on attribute– Category– Quantity
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Quantity
• Graduated colors– Color ramps – which work best?
• Graduated Symbols (classification)
• Editing legend entries for the TOC
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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)
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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
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Quantitative maps
• Displays quantitative data – interval or ratio data and even ordinal data
• A graduated ramp or palette is used
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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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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!
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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)
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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
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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
• 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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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
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•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.
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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