ArcGIS Overview Lecture 1: Software Layer characteristics Thematic maps

Outline  ArcGIS overview  Software- ArcMap, ArcCatalog, & ArcToolbox  Layer characteristics  Thematic maps 2

ArcGIS Overview- the software: ArcMap, ArcToolbox, & ArcCatalog Lecture 1

ArcMap (Desktop GIS) Table of contents Tools toolbar Identify results window Map document Window or data frame Standard toolbar Main menu 4 Draw toolbar: Customize> Toolbars> Draw Context menu: Right click a Data layer Open/ add data layer Open Map document

Map documents  (.mxd) extension  “Points” to layers  Saves layer colors, symbology, etc. 5

Adding data to your map  Two layers  USCities (red points, restricted to major cities)  USStates (yellow polygons) 6 GIS TUTORIAL 1 - Basic Workbook

Adding map layers Separate files added to a map document 7

8 Format types of data in ArcGIS

Geodatabases The geodatabase is a "container" used to hold a collection of datasets (GIS features, tables, raster images, etc). Country layer Graticule layer World.gdb 9

ArcCatalog Arranges and manages geographic information in workspace folders and geodatabases. 10

ArcToolbox Advanced tools with form-based input by users 11

Layer characteristics Lecture 1

Layer characteristics: 13 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: 14 Open mxd or add layer

Layer characteristics: 15 Set the order of display or show source of files Note: order of display is the only option to change drawing order

Layer characteristics: 16 Visibility of layers:

Layer characteristics: 17 Selectability of layers:

Layer characteristics: 18 Options:

Layer characteristics: TOC & Right click 19 Context menu: Right click a data layer & select properties Change symbol type & color

Layer characteristics: TOC & Right click 20 Context menu: Right click a data layer & select properties Change symbol type & color

Layer characteristics: TOC & Right click 21 Context menu: Right click a data layer & select properties Set the field to label and characteristics

Thematic maps Lecture 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) 23

24 Choropleth map example Map 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

Choropleth map example  Percentage of vacant housing units by county 25

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 26 Break points

How to classify ranges in ArcMap 27

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 28

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% 29

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 30

Classifications Use mathematical formulas when possible.  Exponential scales  Popular method of increasing intervals  Use break values that are powers such as 2 n or 3 n  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 31

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

U.S. population by state, Original map (natural breaks)

Not good because too many values fall into low classes 34 Equal interval scale

Shows that an increasing width (geometric) scale is needed 35 Quantile scale

Custom geometric scale  Experiment with exponential scales with powers of 2 or 3. 36

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 37 Normalizing data

Nonnormalized data Number of vacant housing units by state,

Normalized data Percentage vacant housing units by state,

California population by county, Nonnormalized data

41 California population density, 2007 Normalized data

Normalize Data to conform to a standard 42 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.

43 TOC Layout View 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

44 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

45 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

46 Other Types of Thematic Maps: Graduated Symbols

47 GIS TUTORIAL 1 - Basic Workbook Other Types of Thematic Maps: Proportional Symbols

48 Other Types of Thematic Maps: Dot Density

49 Other Types of Thematic Maps: Unique Values