arcgis overview lecture 1: software layer characteristics thematic maps
TRANSCRIPT
ArcGIS Overview
Lecture 1:Software
Layer characteristicsThematic maps
Outline
ArcGIS overview
Software- ArcMap, ArcCatalog, & ArcToolbox
Layer characteristics
Thematic maps
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ArcGIS Overview- the software:ArcMap, ArcToolbox, & ArcCatalog
Lecture 1
ArcMap (Desktop GIS)
Table ofcontents
Toolstoolbar
Identifyresultswindow
Map documentWindow or data frame
Standard toolbar
Main menu
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Draw toolbar:Customize>Toolbars>Draw
Context menu:Right click aData layer
Open/ add data layer
Open Mapdocument
Map documents (.mxd) extension “Points” to layers Saves layer colors, symbology, etc.
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Adding data to your map Two layers
USCities (red points, restricted to major cities) USStates (yellow polygons)
6GIS TUTORIAL 1 - Basic Workbook
Adding map layers
Separate files added to a map document
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Format types of data in ArcGIS
GeodatabasesThe geodatabase is a "container" used to hold a collection of datasets (GIS features, tables, raster images, etc).
Country layer
Graticule layer
World.gdb
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ArcCatalogArranges and manages geographic information in workspace folders and geodatabases.
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ArcToolboxAdvanced toolswith form-basedinput by users
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Layer characteristicsLecture 1
Layer characteristics:
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• Open mxd or add layer
• Table of Contents (TOC) Set the order of display, source, visibility, selection, & options
• Change symbol type & color
• Set the field to label and characteristics
Layer characteristics:
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• Open mxd or add layer
Layer characteristics:
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• Set the order of display or show source of files
Note: order of display is the only option to change drawing order
Layer characteristics:
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• Visibility of layers:
Layer characteristics:
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• Selectability of layers:
Layer characteristics:
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• Options:
Layer characteristics: TOC & Right click
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Context menu:Right click adata layer & select properties
• Change symbol type & color
Layer characteristics: TOC & Right click
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Context menu:Right click adata layer & select properties
• Change symbol type & color
Layer characteristics: TOC & Right click
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Context menu:Right click adata layer & select properties
• Set the field to label and characteristics
Thematic mapsLecture 1
Thematic Maps: Choropleth Color-coded polygon maps Use monochromatic scales or saturated
colors Represent numeric values (e.g.
population, number of housing units, percentage of vacancies)
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Choropleth map exampleMap using color or pattern to show different values over space (uses a color ramp). To create: In TOC, right click layer, select properties, select symbology
Legend
States
Counties
POP2003
-99 - 162000
162001 - 559264
559265 - 1370157
1370158 - 3581375
3581376 - 9873548
Choropleth map example Percentage of vacant housing units by
county
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Classifying dataProcess of placing data into groups (classes orbins) 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
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Break points
How to classify ranges in ArcMap
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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
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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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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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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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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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U.S. population by state, 2000
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Original map (natural breaks)
Not good because too many values fall into low classes
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Equal interval scale
Shows that an increasing width (geometric) scale is needed
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Quantile scale
Custom geometric scale Experiment with exponential scales with
powers of 2 or 3.
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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
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Normalizing data
Nonnormalized data
Number of vacant housing units by state,
2000
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Normalized data
Percentage vacant housing units by state,
2000
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California population by county, 2007
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Nonnormalized data
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California population density, 2007
Normalized data
Normalize Data to conform to a standard
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•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.
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TOC TOCLayout View
To Create More Meaningful Text in Legends
1. Left click to highlight the layer in the TOC2. Type the desired text3. When the legend is added on the layout, the new text will display
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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
Layout View
1
2
3 4
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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
Range- Reverse Sorting
Symbol- Flip Symbols
Result
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Other Types of Thematic Maps: Graduated Symbols
Percent
5.9 - 13.3
14.2 - 19.3
20.0 - 25.8
28.1 - 37.3
Percent Poverty By County, 1990
47GIS TUTORIAL 1 - Basic Workbook
Other Types of Thematic Maps: Proportional Symbols
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Percent
Percent Poverty By County, 1990
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1 Dot = 1 Percent
Percent Poverty By County, 1990
Other Types of Thematic Maps: Dot Density
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Other Types of Thematic Maps: Unique Values