Introduction to GIS

Ghassan Mikati, Ph.D

GIS Expert

A computer system which can hold and use data

describing places on the earth's surface.

What is GIS?GIS is:

A mapping software – such as Electronic Atlas:It displays pictures of geographic areas on the computer

It provides information about these areas

It provides ability to alter graphics

And even more than that, it has the ability:To create graphics using information database

To import external information & databases

To use tabular information to create charts & graphs

And to analyze information statistically

Components of GIS

Database

Computer Hardware & SoftwareOrganizational

Structure & People

Components of GIS

Hardware: the computer on which GIS operates

Software: which provides the

functions and tools needed to store,

analyze, and display geographic

information.

Data: geographic data & related

tabular data

People: GIS users who range from

specialists to simple users

Methods: a designed plan and business rules

Raster vs. Vector GIS works with two models:

Vector: information is encoded

and stored as a collection of

x,y coordinates

Raster: comprises a collection

of grid cells

GIS stores information about the world as a collection of thematic layers that can be linked together by geography

GIS Layers

On a Map…Every object is called Map Feature…

Roads

Park River

Geographic Features

Geographic features are represented by two types of data.

SPATIAL DATA ATTRIBUTE DATA

Street NameAddress range on leftAddress range on rightLength to travelDirections to travel

Street NameAddress range on leftAddress range on rightLength to travelDirections to travel

On a Map…Map features are represented as points, lines or areas…

Roads

as lines

Park & River as areas

Sites

as points

Related Information…GIS stores all descriptive information about features as attributes in a GIS database.

Each column stores a different attribute

Each row relates

to a single feature

The Map/Table linkAny change in the attribute table is reflected on the map.

The Map/Table link

Features & AttributesSets of features and attributes together are called themes:

RiverParksBuildings

Roads

GIS DatabaseAll themes together make the GIS database

River

Parks

Buildings

Roads

On a Map…Map scale controls the size of features and shapes used to represent them, i.e. when map scale increases, so does the size of the map feature.

Roads as lines

Roads as polygon

City as point

Building

as polygon

Getting Answers to QuestionsWith GIS we can:

Get information about features

Find features based on their attributes

Analyze features locations

Here we are seeking to find out what exists at a particular location.

A location can be described in many different ways using, for example, place name, or latitude and longitude coordinates

Identifier: 565-88-221

Area: 108,900,245

Owner: John Morris

Address: 3233 Texas St.

Zoned land use: Industrial

Assessment: $950,000

Getting other types of information about a feature

Instead of identifying what exists at a given location, you want to find a location where certain

conditions are satisfied. For example, you wish to find a house assessed at

less than $200,000 with 4 bedrooms and made of wood.

Map

Find features based on attributes they share

4 Bedrooms

More than a certain area

Within a

certain price

Result

This seeks to discover the differences between an area as the result of the

passing of time.

City in 1950 City in 1990

This seeks to discover what types of patterns may exist in the newly created data file

that were not visible before. For example you may wish to know where motor vehicle accidents occur and at what

times.

What kinds of patterns exist for motor vehicle accidents?Where do they occur and at what times?

GIS locates features with regards to their location to each other:

Features adjacent to…

Features within a certain distance

Features within a certain area

Etc…

Looking for an apartment within 0.5 km from high school

Schools

High SchoolApartments

for sale

Apartments

for sale

within

0.5 km

Major Areas of Practical Application of GIS Technology

vehicle routing and schedulinglocation analysis, site selectiondevelopment of evacuation plans

Street Network-Based

• locating underground pipes, cables

• balancing loads in electrical networks

• planning facility maintenance• tracking energy use

Facilities Management

Major Areas of Practical Application of GIS Technology

• zoning, subdivision plan review• land acquisition• environmental impact statements• water quality management

Land Parcel-Based

Major Areas of Practical Application of GIS Technology

• forest management• habitat, migration routes management• wild and scenic rivers preservation• recreation resources planning• wetland preservation• agricultural lands management• groundwater modeling and

contamination tracking

Natural Resource-Based

Major Areas of Practical Application of GIS Technology