Chapter Extension

17Geographic Information

Systems

Q1: What are the components of a geographic information system?

Q2: How are GIS maps constructed?

Q3: How do organizations use GIS?

Q4: How do maps deceive?

Study Questions

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GIS: Information system that captures, stores, analyzes, and displays geospatial data and presents in meaningful context

Q1: What Are the Components of a Geographic Information System?

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Data ordered in reference to Earth or other physical location

Map of Data in Previous Slide

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1990 •Most GIS were stand-alone desktop applications

1990s•Some capability moved to thick-client, client-server

applications

2000

•Some GIS applications, notably graphical viewers such as Google Maps and Bing Maps, moved to cloud-based, thin-client applications

Today

•GIS applications using HTML 5 in development •GIS operating on all platforms from stand-alone

computers to thin clients accessing data in the cloud

History of GIS

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Structure of GIS Application Components

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Input: surveying equipment, cameras, satellite devices, GPS devices, map scanners and more

ArcGIS, Autodesk, MapInfo, Bentley GIS. Open-source GIS include GRASS and uDig and others.

GIS applications get geospatial data from service like Google Earth or Bing Maps, add organizational-specific data from own database, and displays that data in browsers for users.

Software: GIS Applications

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Tools for input, manipulation, and structuring GIS outputs can be complicated and difficult to use. Need geospatial analyst for particular tasks

Go to http://viewer.nationalmap.gov/viewer to learn more

Data: U.S. Government Provides Different Types of Free Geospatial Data

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Typical Procedures for GIS Use

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• Directions to friend’s house; map of customer’s premise; all houses in neighborhood for sale in given price range

Casual users

• Company deciding how best to locate retail stores; police department wants to know if locations of crimes in city are changing.

Business Intelligence (BI)

users

• Create GIS systems in response to requirements

Developers

• Run system and maintain databaseOperations personnel

• Capture geospatial data Field personnel

People: Common Types of Users

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GIS map is a composite of several maps placed over one another

Raster vs. Vector Maps

Raster map consists of pixels with some

value, such as color, elevation,

temperature, etc.Easy to create

from pictures and scanners at scale created; however

blur when enlarged.

Vector map consists of points, lines, and

shapes

Difficult to create, but scale perfectly

Q2: How Are GIS Maps Constructed?

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Raster and Vector Format

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Examples Of Raster and Vector Maps

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Bing vector map

Bing raster map

Vector and Raster Image

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Constructing map of Earth requires answering three difficult questions:

1. How big is it?2. What shape is

it?3. How can

curved surface of Earth be shown flat ?

Mapping the Earth

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Mercator Projection

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Source Page: http://www.learnnc.org/lp/multimedia/14596

• Increasingly distorts areas according to their distance from equator

•Google Maps uses variant of Mercator

Peters Projection

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Source Page: http://commons.wikimedia.org/wiki/File:Gall-peters.png

Preserves areas but distorts angles and cannot be used for navigation

Mercator and Peters Map Projections

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Source: www.ODTmaps.com

Most GIS applications have tools for converting commonly used projections

•Military Grid Coordinate System (MGCS) Geocoding

•60 north-south zones•Zones divided into squares 6 degrees east/west and 8 degrees north/south. Each square has two letter identifier. Within a square, distances measured in meters from east boundary and north boundary.

Coordinates based on

latitude and longitude

Many methods to create maps and express locations

When combining data from different sources, GIS application must convert that data into consistent

formats.

Where Is It?

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Q3: How Do Organizations Use GIS?

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Bing-based Application Developed by Harley-Davidson

User-Generated Content via GIS: Plan Your Next Ride

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User Contributed Data

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Benefits

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• Promotes museum. • Raises barrier to entry for other

motorcycle manufactures• Creates brand loyalty among

customers. • Re-enforces alliances between

manufacturer and franchises. • Re-enforces alliances with

cooperating hotels. • Provides users opportunity to

contribute content and form social networks.

How site contribute

s to Harley-

Davidson’s

competitive

strengths?

Miami, Florida, 311-Call Patterns

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Bing-based Application Developed by the City Of Miami

Geofence: A geographic boundary set up within a GIS. One application is to notify personnel when trucks or other containers are nearing their destination.

Protect company personnel when they move into a non-safe zone.

Blue CRM is a risk management firm that provides just this capability. http://www.bluecrm.co.uk

Using GIS for Asset Tracking

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 GIS for Business Intelligence

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Community Health uses GIS to identify underserved areas.www.HealthLandscape.org

a. Total Vacant Residences,Q1 2008

b. Total Vacant Residences,Q4 2008

Maps Used to Assess Change in Need for Medical AccessFigure CE17-16

GIS for Business Intelligence (cont’d)

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Community Health uses GIS to investigate changes in population and economic conditions

• Maps used for propaganda, advertising, and biased reporting and analysis

• Pay attention to map orientation, projection, scale, and source

Q4: How Do Maps Deceive?

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2004 US Presidential Election results

Voted Republican

Voted Democratic Thematic, Choropleth Map ExampleFigure CE17-18

Conveys homogeneity that seldom exists

Problems with Choropleth Maps

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Thematic map shows themes about geographic locations

Choropleth map displays colors, shades, or patterns in accordance with category values ofunderlying data

• What is the information in this map?

―At least one bee found in county in year

• Too many colors make interpretation difficult

Problems with Choropleth Maps (cont’d)

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Results depend on definition of regions

Modifiable Areal Unit Problem (MAUP): Average Housing Prices by City Block

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Only Difference Between the Figures Below Is MAUP Gerrymandering

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Don’t jump to conclusions when viewing maps, especially choropleth maps. Take time to understand the bias of a map, required distortion, false homogeneity of choropleth maps, use of emotional colors, and MAUP.

First Grouping of Data Second Grouping of Data

Active Review

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Q1: What are the components of a geographic information system?

Q2: How are GIS maps constructed?

Q3: How do organizations use GIS?

Q4: How do maps deceive?

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