1. GIS Tutorial 1
Lecture 2
Map design

2. Outline Choropleth maps Colors Vector GIS display GIS queries
Map layers and scale thresholds
Hyperlinks and map tips
GIS TUTORIAL 1 - Basic Workbook

3. Lecture 2
Choropleth maps

4. Choropleth maps Color-coded polygon maps
Use monochromatic scales or saturated colors
Represent numeric values (e.g. population, number of housing units, percentage of vacancies)
GIS TUTORIAL 1 - Basic Workbook

5. Choropleth map example
Map using color or pattern
to show different values over space (uses a color ramp)
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6. Choropleth map example
Percentage of vacant housing units by county
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7. Classifying data Break points
Process of placing data into groups (classes or
bins) that have a similar characteristic or value
Break points
Breaks the total attribute range up into these intervals
Keep the number of intervals as small as possible (5-7)
Use a mathematical progression or formula instead of picking arbitrary values
Break
points
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8. How to classify ranges in ArcMap
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9. Classifications Natural breaks (Jenks)
Picks breaks that best group similar values together naturally and maximizes the differences between classes
Generally, there are relatively large jumps in value between classes and classes are uneven
Based on a subjective decision and is the best choice for combining similar values
Class ranges specific to the individual dataset, thus it is difficult to compare a map with another map
Because the class ranges are specific to the individual dataset, it is difficult to compare a map with another map and to choose the optimum number of classes, especially if the data is evenly distributed.
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10. Classifications Quantiles
Places the same number of data values in each class
Will never have empty classes or classes with too few or too many values
Attractive in that this method produces distinct map patterns
Analysts use because they provide information about the shape of the distribution.
Example: 0–25%, 25%–50%, 50%–75%,75%–100%
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11. Classifications Equal intervals
Divides a set of attribute values into groups that contain an equal range of values
Best communicates with continuous set of data
Easy to accomplish and read
Not good for clustered data
Produces map with many features in one or two classes and some classes with no features
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12. Classifications Use mathematical formulas when possible.
Exponential scales
Popular method of increasing intervals
Use break values that are powers such as 2n or 3n
Generally start out with zero as an additional class if that value appears in your data
Example: 0, 1–2, 3–4, 5–8, 9–16, and so forth
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13. Classifications Use mathematical formulas when possible
Increasing interval widths
Long-tailed distributions
Data distributions deviate from a bell-shaped curve and most often are skewed to the right with the right tail elongated
Example: Keep doubling the interval of each category, 0–5, 5–15, 15–35, 35–75 have interval widths of 5, 10, 20, and 40.
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14. Original map (natural breaks)
U.S. population by state, 2000
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15. Equal interval scale
Not good because too many values fall into low classes
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16. Quantile scale
Shows that an increasing width (geometric) scale is needed
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17. Custom geometric scale
Experiment with exponential scales with powers of 2 or 3.
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18. Normalizing data Divides one numeric attribute by another in order to
minimize differences in values based on the size of
areas or number of features in each area
Examples:
Dividing the number of vacant housing units by the total number of housing units yields the percentage of vacant units
Dividing the population by area of the feature yields a population density
For example, dividing the 18- to 30-year-old population by the total population yields the percentage of people aged 18–30. Similarly, dividing a value by the area of the feature yields a value per unit area, or density.
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19. Nonnormalized data Number of vacant housing units by state, 2000
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20. Normalized data Percentage vacant housing units by state, 2000
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21. Nonnormalized data California population by county, 2007
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22. Normalized data California population density, 2007
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23. Normalize Data to conform to a standard
Right-click the layer you want to draw showing a quantitative value in the table of contents and click Properties.
Click the Symbology tab.
Click Quantities and click graduated colors.
Click the Value drop-down arrow and click the field that contains the quantitative value you want to map.
Click the Normalization drop-down arrow and click a field to normalize the data.
ArcMap divides this field into the Value to create a ratio.
Normalize Data to conform to a standard
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24. To Create More Meaningful Text in Legends
1. Left click to highlight the layer in the TOC
2. Type the desired text
3. When the legend is added on the layout, the new text will display
TOC
TOC
Layout View
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25. OR- To Create More Meaningful Text in Legends
1 In Layout View, right click the legend box
2 Select Convert To Graphics
3 Right click the Graphics text box legend, select Ungroup
4 Double left click text, then type desired text 1 2 4 3
Layout View
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26. To sort value ranges in descending order:
Right-click the layer you want to draw showing a quantitative value in the table of contents and click Properties.
Click the Symbology tab.
Click Quantities and click graduated colors.
Click the Value drop-down arrow and click the field
that contains the quantitative value you want to map.
Click the Range tab and click Reverse Sorting.
ArcMap places the ranges in descending order.
Select OK
To reverse the symbol color:
Select the symbol tab
Select Flip Symbols
Symbol- Flip Symbols
Result
Range- Reverse Sorting
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27. Other Types of Thematic Maps: Graduated Symbols
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28. Other Types of Thematic Maps: Proportional Symbols
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29. Other Types of Thematic Maps: Dot Density
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30. Other Types of Thematic Maps: Unique Values
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31. Lecture 2
colors
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32. Color overview Hue is the basic color
Value is the amount of white or black in the color
Saturation refers to a color scale that ranges from a pure hue to gray or black
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33. Color wheel Device that provides guidance in choosing colors
Use opposite colors to differentiate graphic features
Three or four colors equally spaced around the wheel are good choices for differentiating graphic features
Use adjacent colors for harmony, such as blue, blue green, and green or red, red orange, and orange
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34. Light vs. dark colors Light colors associated with low values
Dark colors associated with high values
Human eye is drawn to dark colors
In the above example, the first set of all dark lines are static. The middle example leads the eye in a downward direction (dark to light). Reversing the values of the lines leads the eye upward.
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35. Contrast The greater the difference in value between an
object and its background, the greater the
contrast
In the above examples, the lighter value recedes into the light background.
The design with the greatest contrast makes the darker object more dominant.
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36. Monochromatic color scale
Series of colors of the same hue with color value varied from low to high
Common for choropleth maps
The darker the color in a monochromatic scale, the more important the graphic feature
Use more light shades of a hue than dark shades in monochromatic scales
The human eye can better differentiate among light shades than dark shades
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37. Monochromatic map
Values too similar
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38. Monochromatic map A better map, more contrast
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39. Dichromatic color scale
An exception to the typical monochromatic scale used in most choropleth maps
Two monochromatic scales joined together with a low color value in the center, with color value increasing toward both ends
Uses a natural middle point of a scale, such as 0 for some quantities (profits and losses, increases and decreases)
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40. Dichromatic map
Symmetric break points centered on 0 make it easy to interpret the map
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41. Color tips Colors have meaning Cool colors Warm colors
Political and cultural
Cool colors
Calming
Appear smaller
Recede
Warm colors
Exciting
Overpower cool colors
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42. Color tips
Do not use all of the colors of the color spectrum, as seen from a prism or in a rainbow, for color coding
If you have relatively few points in a point layer, or if a user will normally be zoomed in to view parts of your map, use size instead of color value to symbolize a numeric attribute
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43. Color tips If you have many polygons to symbolize, it is better to
use polygon centroid points with color rather than
polygon choropleth maps.
City of Pittsburgh housing units by block (quantile)
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44. Changing colors in ArcMap
Choose color, more colors…
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45. Learn more about GIS colors
Website
Books
Brewer, Cynthia A Designed Maps: A Sourcebook for GIS Users. Redlands: ESRI Press
Brewer, Cynthia A Designing Better Maps: A Guide for GIS Users. Redlands: ESRI Press
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46. Lecture 2
Vector gis display
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47. Points, lines, polygons Point Line Polygon x,y coordinates
starting and ending point and may have additional shape vertices (points)
Polygon
three or more lines joined to form a closed area
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48. Feature attribute tables
Store characteristics for vector features
Layers can be displayed using attributes
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49. Displaying points Single symbols All CAD calls
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50. Displaying points Same features, different points Based on attributes
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51. Displaying points Industry specific (e.g. crime analysis)
Good for large scale (zoomed in) maps
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52. Displaying points Industry specific (e.g. schools)
Not good for multiple features at smaller scales
Simple points better for analysis
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53. Displaying points Quantities Use exaggerated sizes
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54. Displaying lines
For analytical maps, most lines are ground features and should be light shades (e.g. gray or light brown)
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55. Displaying lines
Consider using dashed lines to signify less important line features and solid lines for the important ones
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56. Displaying polygons Consider using no outline or dark gray for
boundaries of most polygons
Dark gray makes the polygons prominent enough, but not so much that they compete for attention with more important graphic features
Map on the right is population by Census block (2000), City of Pittsburgh
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57. Displaying polygons Consider using texture for black and white copies
Map displays population for Allegheny County, PA municipalities (2000)
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58. Graphic hierarchy
Assign bright colors (red, orange, yellow, green, blue) to important graphic elements
Features are known as figure
All features in figure
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59. Graphic hierarchy
Assign drab colors to the graphic elements that provide orientation or context, especially shades of gray
Features known as ground
Circles in figure, squares and lines in ground
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60. Graphic hierarchy
Place a strong boundary, such as a heavy black line, around polygons that are important to increase figure
Use a coarse, heavy cross-hatch or pattern to make some polygons important, placing them in figure
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61. Graphic hierarchy example
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62. Lecture 2
Gis queries
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63. GIS queries
Powerful relationship between data table and vector-based graphics—unique to GIS
Records from a feature attribute table are selected by using query criteria
Query will automatically highlight the corresponding graphic features
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64. Simple attribute queries
Simple query criterion
<data attribute>< logical operator><value>
NatureCode ='DRUGS'
DATE >= ' '
% wild card
% symbol stands for zero, one, or more characters of any kind
NAME like ' BUR%'
Selects any crime with names starting with the letters BUR, including burglaries (BUR), business burglaries(BURBUS), and residential burglaries (BURRES)
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65. Simple attribute queries
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66. Compound attribute queries
Compound query criteria
Combine two or more simple queries with the logical connectives AND or OR
"NATURE_COD" = 'DRUGS' AND "DATE" >
Selects records that satisfy both criteria simultaneously
Result are drug crimes that were committed after August 1, 2004
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67. Compound attribute queries
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68. Layer groups, scale thresholds
Lecture 2
Layer groups, scale thresholds

69. Layer groups Organizes layers Groups and names logically
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70. Map Layer file (.lyr) Display certain characteristics of a dataset
Show street subset that is classified by small, medium, or large
Dataset properties such as color & line width are saved
and applied to similar datasets.
To create layer file
right click layer
Select Save as
layer file
-type layer filename
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71. Group Layer (.lyr) To create a Group Layer:
Right click the data frame text and
Select New Group Layer
Select the New Group layer &
Add Data (i.e.rail & interstate)
Right click the New Group layer text
and select Save as Layer File
In the save layer pop up window,
type the name of the new layer file
i.e. Transportation Group.lyr
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72. Minimum scale threshold
When zoomed out beyond this scale, features will not be visible
Tracts not visible when zoomed to the USA
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73. Minimum scale threshold
Tracts displayed when zoomed in
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74. Maximum scale threshold
When zoomed in, features will not be visible
State population will disappear when zoomed in to a state
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75. Hyperlinks and map tips
Lecture 2
Hyperlinks and map tips

76. Hyperlinks
Links images, documents, Web pages, etc. to features on a map
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77. Map tips
Provide an additional way to find information about map features
Pop up as you hover the mouse pointer over a feature
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78. Summary Choropleth maps Colors Vector GIS display GIS queries
Map layers and scale thresholds
Hyperlinks and Map tips
GIS TUTORIAL 1 - Basic Workbook