Geographic Information System

Geog 258: Maps and GIS

February 17, 2006

Outlines

• What is GIS?

• What can GIS do?

• GIS applications

• Components of GIS

• What is special about GIS?

• GIS and geographic questions

What is GIS?

• An information system that is designed to work with geographically referenced data

• Information system: hardware, software, database

• Geographically referenced data: coordinate system

Image from esri.com

What is GIS?Different views

• Functionalities view• A system for capturing, storing, retrieving, manipulating, analyzing, and

displaying data which are spatially referenced to the Earth -- Chorley, 1987•  • Information system view• Geographic Information System (GIS) is a kind of Information System (IS)

designed to work with geographically referenced data•  • Database view• A database system with specific capabilities for spatially-referenced data, as

well as a set of operations for working [analysis] with the data -- Start and Estes, 1990

•  • Disciplinary view• GIS as a multidisciplinary science: GIS is an integrated multidisciplinary

science consisting of the following traditional disciplines.

Themes are organized spatially

• GIS organizes the information about place by layers

Themes are put into a computer

Modeling the phenomenon…

Group of spatial objects with related entity type

Digital Representation of Spatial Entities

Phenomenon of interest in the real world

Layers

Spatial Objects

Spatial Entities

e.g. point, line, polygon

e.g. city layer, SARS layer, Tornado layer

e.g. urban growth, Tornado movementSARS spread, crime, consumer behavior

Abstraction

Putting the geography into a computer…

Link between where and what

• In most of GIS, spatial objects are linked to attributes • What about the link between where and when?

Representing in computer…

Multidisciplinary Science

• Geography• Mathematics• Remote Sensing• Cartography• Surveying• Geodesy• Statistics• Computer Science• Operations Research

Spatial Component

• Almost everything that happens, happens somewhere. – Estimates are that 80% of all data has a spatial

component.

• Knowing where something happens is of critical importance to our daily life and others

• Data from most sciences can be analyzed “spatially”.

Spatial Query

“The application of GIS is only limited by the imagination of those who use it.”

• Archaeology, agriculture, banking, defense and intelligence, electric and gas, engineering- pipeline, engineering- surveying, federal government, fire/EMS/disaster/homeland security, forestry, health and human services, insurance, education, landscape architecture, law enforcement and criminal justice, libraries and museums, location service, marine/cost/oceans, media, mining/earth science, natural resources, petroleum, real estate, retail business, state and local government, telecommunications, transportation, universities, and water/wasterwater

Network solutions

Ecosystem management

3D mine with well data

Environmental monitoring toxic plume

Site location and client distance

Modeling of future trends

Components of GIS

Components of GIS: hardware

• Equipment needed to support the many activities of GIS ranging from data collection to data analysis

• Data acquisition: surveying equipments, GPS receiver, remote sensing equipments, digitizer, scanner

• Data compilation/analysis: workstation

• Data publishing: web-server, mobile computing device

Components of GIS: software

• The definition of GIS by functionalities:

A system for capturing, storing, retrieving, manipulating, analyzing, and displaying data which are spatially referenced to the Earth

• So GIS software provides those functionalities

Components of GIS: data

• Core of GIS• Kinds of geographic data are extensive

– Satellite image– Maps– Table

• Metadata: data about data, documents characteristics of data

• Accounts for 70-80% of GIS projects in the early stage• Impact of internet is huge; geographic data is increasingly

accessible to the general public

What is special about GIS?

• Most problems exist in a geographic context. GIS puts various themes together.

Integration

What is special about GIS?

• Maps are worth a thousand words

Visualization

“A map is worth a thousand word”

What is special about GIS?

• Data: raw facts, context-free

• Information: interpretative facts

• Knowledge: understand the reason by the knower

• GIS transform data into information and knowledge by integrating data of different kinds and sources

Transformation

GIS and geographic questions

• How it looks? Form pattern• How it works? Process prediction• GIS can help you understand process by examining form

Job Accessibility in Columbus, OH

Value of job accessibility measure is shaded:High <--------------------------------------> LowOrange ------ Yellow ------ Green ------ Blue

Form & process

How it looks: the pattern of high job accessibility concentrated along interstate highway

How it works: the relationship between job accessibility and transportation network

GIS and geographic questions

• General theory is important, but context-dependent idiosyncrasy is important also

• GIS analysis allows you to understand the world better by combining general knowledge with specific information

General & specific

Process of landslides can be understood better by applying general rules to information derived from layers at the local area