GIS Tutorial 1 - PowerPoint PPT Presentation

Loading...

PPT – GIS Tutorial 1 PowerPoint presentation | free to download - id: 52ccc2-YTg1M



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

GIS Tutorial 1

Description:

GIS Tutorial 1 Lecture 2 Map design * * City of Pittsburgh housing units by block (quantile) * * Map on the right is population by Census block (2000), City of ... – PowerPoint PPT presentation

Number of Views:190
Avg rating:3.0/5.0
Slides: 79
Provided by: Kristen147
Learn more at: http://urban.csuohio.edu
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: GIS Tutorial 1


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

3
Choropleth maps
  • Lecture 2

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)

5
Choropleth map example
Map using color or pattern to show different
values over space (uses a color ramp)
6
Choropleth map example
  • Percentage of vacant housing units by county

7
Classifying data
  • 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

8
How to classify ranges in ArcMap
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

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 025, 2550, 5075,75100

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

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, 12, 34, 58, 916, and so forth

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, 05, 515, 1535, 3575 have interval
    widths of 5, 10, 20, and 40.

14
Original map (natural breaks)
U.S. population by state, 2000
15
Equal interval scale
  • Not good because too many values fall into low
    classes

16
Quantile scale
  • Shows that an increasing width (geometric) scale
    is needed

17
Custom geometric scale
  • Experiment with exponential scales with powers of
    2 or 3.

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

19
Nonnormalized data
  • Number of vacant housing units by state, 2000

20
Normalized data
  • Percentage vacant housing units by state, 2000

21
Nonnormalized data
California population by county, 2007
22
Normalized data
California population density, 2007
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.

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
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
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
  • Select OK

Symbol- Flip Symbols
Result
Range- Reverse Sorting
27
Other Types of Thematic Maps Graduated Symbols
28
Other Types of Thematic Maps Proportional Symbols
29
Other Types of Thematic Maps Dot Density
30
Other Types of Thematic Maps Unique Values
31
colors
  • Lecture 2

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

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

34
Light vs. dark colors
  • Light colors associated with low values
  • Dark colors associated with high values
  • Human eye is drawn to dark colors

35
Contrast
  • The greater the difference in value between an
  • object and its background, the greater the
  • contrast

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

37
Monochromatic map
  • Values too similar

38
Monochromatic map
  • A better map, more contrast

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)

40
Dichromatic map
  • Symmetric break points centered on 0 make it easy
    to interpret the map

41
Color tips
  • Colors have meaning
  • Political and cultural
  • Cool colors
  • Calming
  • Appear smaller
  • Recede
  • Warm colors
  • Exciting
  • Overpower cool colors

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

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.

44
Changing colors in ArcMap
  • Choose color, more colors

45
Learn more about GIS colors
  • Website
  • http//colorbrewer2.org/
  • Books
  • Brewer, Cynthia A. 2008. Designed Maps A
    Sourcebook for GIS Users. Redlands ESRI Press
  • Brewer, Cynthia A. 2005. Designing Better Maps A
    Guide for GIS Users. Redlands ESRI Press

46
Vector gis display
  • Lecture 2

47
Points, lines, polygons
  • Point
  • x,y coordinates
  • Line
  • starting and ending point and may have
    additional shape vertices (points)
  • Polygon
  • three or more lines joined to form a closed area

48
Feature attribute tables
  • Store characteristics for vector features
  • Layers can be displayed using attributes

49
Displaying points
  • Single symbols
  • All CAD calls

50
Displaying points
  • Same features, different points
  • Based on attributes

51
Displaying points
  • Industry specific (e.g. crime analysis)
  • Good for large scale (zoomed in) maps

52
Displaying points
  • Industry specific (e.g. schools)
  • Not good for multiple features at smaller scales
  • Simple points better for analysis

53
Displaying points
  • Quantities
  • Use exaggerated sizes

54
Displaying lines
  • For analytical maps, most lines are ground
  • features and should be light shades (e.g. gray
  • or light brown)

55
Displaying lines
  • Consider using dashed lines to signify less
  • important line features and solid lines for the
  • important ones

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

57
Displaying polygons
  • Consider using texture for black and white
  • copies

58
Graphic hierarchy
  • Assign bright colors (red, orange, yellow, green,
    blue) to important graphic elements
  • Features are known as figure

All features in figure
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
59
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

61
Graphic hierarchy example
62
Gis queries
  • Lecture 2

63
GIS queries
  • Powerful relationship between data table and
    vector-based graphicsunique to GIS
  • Records from a feature attribute table are
    selected by using query criteria
  • Query will automatically highlight the
    corresponding graphic features

64
Simple attribute queries
  • Simple query criterion
  • ltdata attributegtlt logical operatorgtltvaluegt
  • NatureCode 'DRUGS'
  • DATE gt '20040701'
  • 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)

65
Simple attribute queries
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" gt 20040801
  • Selects records that satisfy both criteria
    simultaneously
  • Result are drug crimes that were committed after
    August 1, 2004

67
Compound attribute queries
68
Layer groups, scale thresholds
  • Lecture 2

69
Layer groups
  • Organizes layers
  • Groups and names logically

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

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

72
Minimum scale threshold
  • When zoomed out beyond this scale, features will
    not be visible
  • Tracts not visible when zoomed to the USA

73
Minimum scale threshold
  • Tracts displayed when zoomed in

74
Maximum scale threshold
  • When zoomed in, features will not be visible
  • State population will disappear when zoomed in to
    a state

75
Hyperlinks and map tips
  • Lecture 2

76
Hyperlinks
  • Links images, documents, Web pages, etc. to
    features on a map

77
Map tips
  • Provide an additional way to find information
    about map features
  • Pop up as you hover the mouse pointer over a
    feature

78
Summary
  • Choropleth maps
  • Colors
  • Vector GIS display
  • GIS queries
  • Map layers and scale thresholds
  • Hyperlinks and Map tips
About PowerShow.com