Information Systems and GIS
Chapter 2 Slides from
James Pick, Geo-Business: GIS in the Digital
Organization, John Wiley and Sons, 2008.
Copyright © 2008 John Wiley and Sons.
DO NOT CIRCULATE WITHOUT
PERMISSION OF JAMES PICK
Copyright (c) 2008 by John Wiley
and Sons
Elements of a GIS
• A GIS
– Accesses spatial boundaries and attribute
(i.e. non-spatial) data
– Analyzes the spatial and attribute data
• A GIS includes:
– A data-base
– Tools, algorithms, and models for manipulate
spatial data and attributes
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Map and Attribute Information
• Spatial boundary data, attributes, and
data-bases form a basis for spatial data.
• Central idea in GIS is location and the
data associated with it.
• Also a key aspect is that the location and
the data can be linked together.
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Design Elements of a GIS
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(Source: Pick, 2007)
Example of Processing with Simple GIS
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(Source: Pick, 2007)
Points, Lines, and Polygons
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(Source: Pick, 2007)
Relationship of Spatial and Attribute
Data in Multiple GIS Layers
Adapted from West, 2000.
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Baseball example of non-spatial
versus spatial query.
Keith Clarke gives the example of baseball cards. If
we associate the X-Y coordinate location of the
stadium that the player is associated with, we are
adding a spatial attribute.
•Example of query without the spatial attribute. “Find
all players with a batting average over .300.
•Example of query with the spatial attribute. “Find all
players with a batting average over .250 and whose
location is within 300 miles of Yankee Stadium.”
(Source: Clarke, 2003)
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Geographic Location
• How is geographic location determined.
Often by latitude and longitude.
• It can be by more advanced coordinate
systems, such as 3-D, but lat-long will do
for now.
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Coordinate System – Lat, Long
• Locations are represented in a GIS with the
use of X and Y coordinates, which represent
real-world coordinates (in 3 dimensions) that
have been projected onto a two dimensional
surface.
• The geographic grid of latitude and longitude
is a commonly used geographic reference
system.
• It is not a true coordinate system, however
because it measures angles from the center
of the earth in degrees, minutes, and
seconds rather than distances on the earth's
surface.
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Diagram of Lat-Long Coordinate
System for the Earth
(Source: Bolstad, 2005)
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GIS in 3 Dimensions – Example of a 3-D
Image of the Built Environment in London
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Map Scale
• Maps reduce the size of the earth.
• Map at 1:1 scale means 1 foot on the map is the
same as 1 foot on the earth. It would be a lifesized drawing.
• 1:500 scale means that 1 foot on the map is the
same as 500 feet on the earth.
• An idea of scale is that 1:40,000,000 implies that
the circumference of the earth at the equator
would map to the size of a postage stamp.
• U.S. – most important scales at 1:100,000 and
1:24,000 (USGS maps).
• Also 1:50,000 is important.
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Geographic Information
• A map stored inside a GIS is described by
coordinates.
• A sophisticated map contains a huge
number of coordinates. This is possible
because of the huge gains in storage
described in the introductory lecture.
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GIS Structures – Features and
Feature Properties
• GIS structures are put together from points, lines, and
areas (polygons).
Points – the basic coordinate location – zero dimensional
Lines – connected together by two points – one
dimensional.
Areas (also called polygons) bounded by three or more
points connected by lines – two dimensional.
Points, lines, and areas are features. They are further
defined by feature properties of size, distribution,
neighborhood, shape, pattern, contiguity, shape, and
orientation.
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Referent Disciplines for GIS Concepts
and Theories
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GPS Devices for Field
Hardened Trimble GPS with ArcPad
Asus R2HV A1 UMPC
Has Bluetooth, Wireless Windows
Vista. Can have GPS Add-on and
connect by Blue Tooth to Digital
Camera
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Satellite
and Aerial
Imagery
Which can
be Input
into a GIS
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Combining Satellite Imagery and
Digital Photo in a GIS
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Spatial Analysis
• GIS analysis techniques consist of methods that are used
in the spatial analysis, modeling, and statistical analysis of
a GIS. This section describes a few of the most common
spatial analysis techniques.
• Spatial analysis consists of analytical techniques that
emphasize the map layers.
• It relates and compares the features of the physical
locations of objects in space (Getis, 1999; Longley and
Batty, 2003). Since it draws from geography,
– it is not familiar to most IS researchers.
• Modeling and statistical analysis methods include many
methods and techniques well known in business
disciplines, but often modified to take into account spatial
relationships. These methods are based both on attribute
and spatial data,
• Specialized statistical methods that include space are
referred to as geostatistics (Getis, 1999).
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Map Overlay
• Since spatial analysis techniques compare
spatial features, they can, for example,
determine how many points are inside a
polygon, how many line segments cross a
polygon boundary, or how much polygons
overlap each other.
• This is done by a technique known as map
overlay
• A practical example would be to ask how many
highways and streets (lines) cross a zone of
retail businesses.
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Spatial Analysis – Map Overlay
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Buffer Analysis
• In buffer analysis, GIS software forms
bands on all sides of a point, line, or
polygon, in order to perform analysis
within the bands.
• A simple example would be to assign halfmile buffers on both sides of a highway, in
order to query how many service stations
are within the buffer.
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Proximity Analysis
• Proximity analysis assesses how close certain
map features are to other map features.
• For instance, it can determine how many
customers are in a grocery store’s trade area.
Class Question. Discuss with your neighbor
another use for Proximity Analysis.
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Modeling and Forecasting
• Forecasting and simulation models can be
built with spatial data, and the results
displayed in map form.
• An example is a model that projects the
population distribution of retail consumers
within a county, based on starting year
data. The future population distributions of
retail consumers can be mapped, to inform
businesses and the public.
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Spatial
Modeling of
Industrial
Locations for
LA Using
Location
Quotient
Source: Greene and Pick, 2006
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Statistical Analysis
• Statistical models are often applied to study the
relationships of certain spatially referenced attributes to
other attributes (Getis, 1999). They include correlation,
regression, analysis of variance (ANOVA), cluster
analysis, principles components, and t tests.
• The input data, as well as the results, of many of these
models can be represented as spatial displays. This
enhances understanding of the geographical effects and
influences.
• Although beyond the scope of this chapter, a specialized
part of statistics, called geostatistics, takes especially
into account spatial effects and interactions, such as
spatial autocorrelation (Getis, 2000). An example is
predicting the future spatial patterns of demand for
advertising services in an urbanized area.
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Summary
• Information Systems and GIS are closely related
to each other
• GIS uses spatial boundaries and attributes to
perform spatial analysis
• GIS requires an underlying knowledge of
geographical principles such as coordinate
systems.
• Specialized equipment is used for input of
information into a GIS
• GIS analysis techniques are utilized to map
comparisions, forecasts, spatial models, and
geo-statistical analysis.
Copyright (c) 2008 by John Wiley
and Sons