ArcGIS Overview Lecture 1: Software Layer characteristics Thematic maps.

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