This document provides an introduction to geographic information systems (GIS). It defines GIS as a collection of hardware, software, and geographic data used to capture, store, analyze and display spatially referenced information. The document gives a brief history of GIS and describes its key components, including spatial data, attribute data, software, and users. It also explains different types of data layers, scales, and four common map types: choropleth, contour, dot, and symbol maps. The overall purpose of the document is to explain the basic concepts and applications of GIS.

1. An Introduction to Geographic
Information Systems (GIS)
Michelle Goulbourne
Presented March 14, 2007
Education Day

2. Objectives
Explain what a geographic information system
(GIS) is.
Provide a history of GIS.
Describe different types of data elements.
Explain spatial scales.
Provide an overview of the map elements.
Introduce 4 different types of maps.

3. Definition
“GIS is a collection of computer hardware, software, and
geographic data for capturing, managing, analyzing, and
displaying all forms of geographically referenced
information.”
http://www.gis.com/whatisgis/index.cfm

4. What is a GIS
Acronym for Geographic Information Systems.
In a GIS, we combine geographic locations with
descriptive data about the locations.
Database and map are linked to allow us to
perform
Queries
Statistical analyses
Geographical analyses
Visualize the results on a map
The goal is to help us gain a better
understanding of our world so we can enhance
planning and decision making.

5. History of GIS
1854 Dr. John Snow created a map to show the locations of
death by cholera in central London. This technique was
used to track the source to a contaminated well.
1960s Roger Tomlinson helped to design and develop the
Canadian GIS (CGIS). The CGIS was used to manage and
analyze Canada Land Inventory Data monitor and the
environment.
1960s SYMAP the 1st mapping package developed by
Howard Fisher.
Increased access to data and technological advances such
as having smaller more powerful computers with greater
storage capacity has helped the field to develop rapidly.

6. Components of a GIS
Geographical locations (spatial data)
Information about the locations (attributes or
non-spatial data)
Software for storing and managing the data.
Computers to facilitate the data storage,
processing and analysis.
People to operate the GIS

7. Data Types
Attribute Data Location Data
What is it? Where is it?
• road • XY Coordinate data
How can we describe it? (latitude and longitude)
• Name
• Class
• Length of road segment
• Date of construction

8. Map Layers
Spatial data contain the
coordinates and identifying
information that is necessary
to draw maps.
A layer is a collection of all
the features in the map that
share some common
characteristic.
Three types of layers can be
represented in a GIS: points,
lines, and areas
When the various layers are
overlaid, they form a map

9. 5 Functions of a GIS
Data acquisition
Preprocessing
Data management
Manipulation and analysis
Generation of maps, images, reports and tables.

10. 7 Types of Questions a GIS Can Answer
Can you map that?
Where is that?
What has changed?
What relationships exist?
Where is it best?
What afffects what?
What if?
Source: Joseph K. Berry (1995) Spatial Reasoning for Effective Reasoning. GIS World Books.

11. Demand and Supply
M. Goulbourne

12. Purchase Power
M. Goulbourne

13. Map of Suitable Areas
M. Goulbourne

14. Representing Map Features
Representation of real-world objects
on a map using symbols and their
locations and geometry with:
Point objects
Line objects
Area or polygon objects
Volume objects
Grid cells
Vector Data Structure
Points, lines and polygons
Raster Data Structure
Grid cells

15. Vector / Raster

16. Scale
Ratio of the size of the entity represented on a map to the size of the
entity in reality.
10km road can be represented by 1cm line on a map.
• 1cm on the map is equal to 1,000,000cm in reality.
• Scale = 1:1,000,000
• Smaller scale -> less detailed
100km road can be represented by 1cm line on a map.
• 1cm on the map is equal to 10,000cm in reality.
• Scale = 1:10,000
• Larger Scale - > more detailed

17. Scale Example
Larger Scale Smaller Scale
http://education.usgs.gov/common/lessons/teaching_about_scale.pdf

18. Anatomy of a Map

19. 1. Chlorpleth Maps
Shows predefined set of areas classified by a particular
attribute of the area.
Water Use
http://en.wikipedia.org/wiki/Image:Choropleth.gif

20. 2. Contour / Isoline Map
Shows lines connecting points of equal value.

21. 3. Dot Map
Plots point locations to show the spatial distribution of the
points.
http://en.wikipedia.org/wiki/Image:Johnsnow.gif

22. 4. Symbol Maps
Use symbols of various sizes
and shapes to represent
variations of an attribute.
“The National Public Toilet Map
is part of the Australian
government's National Continence
Management Strategy (NCMS). The
map allows more Australians with
urinary and fecal incontinence
problems to live and participate in
their communities with dignity and
confidence, by making it easier for
them to find information about the
location of public toilets.“
http://en.wikipedia.org/wiki/National_Public_Toilet_Map

23. Thank you

24. Contact
Michelle Goulbourne
mgoulbourne@diamindhealth.com