INTRODUCTION TO INTRODUCTION TO GEOGRAPHIC GEOGRAPHIC

INFORMATION SYSTEMSINFORMATION SYSTEMS

GOALSGOALS

• Answer the question: “What is a GIS?”Answer the question: “What is a GIS?”• Learn some of the basic terminology Learn some of the basic terminology

used in a GISused in a GIS• Become familiar with the general Become familiar with the general

operations and applications of a GISoperations and applications of a GIS• See some of the analyses performed See some of the analyses performed

in a GISin a GIS

Information SystemsInformation Systems

Data vs. InformationData vs. Information

• Data, by itself, differs from informationData, by itself, differs from information• Data is of little use unless it is Data is of little use unless it is

transformed into informationtransformed into information• Information is an answer to a question Information is an answer to a question

based on raw databased on raw data• We transform data into information We transform data into information

through the use of an Information through the use of an Information SystemSystem

Information SystemInformation System

• More than just an electronic map More than just an electronic map makermaker

• More than a digital databaseMore than a digital database• More than just a software packageMore than just a software package

What is a GIS?What is a GIS?

GIS--What is it?GIS--What is it?No easy answer!No easy answer!

• Geographic/Geospatial Information Geographic/Geospatial Information – information about places on the earth’s information about places on the earth’s

surfacesurface– knowledge about “what is knowledge about “what is where where when”when”– Geographic/geospatial: synonymousGeographic/geospatial: synonymous

• GIS--what’s in the S?GIS--what’s in the S?– Systems: the technologySystems: the technology– Science: the concepts and theoryScience: the concepts and theory– Studies: the societal contextStudies: the societal context

What is a GIS?What is a GIS?• A GIS is a computer system A GIS is a computer system

capable of assembling, capable of assembling, storing, manipulating/ storing, manipulating/ analyzing, and displaying analyzing, and displaying geographically referenced geographically referenced information (spatial)information (spatial), i.e. data , i.e. data identified according to their identified according to their locations. locations.

• A decision support system A decision support system involving the integration of involving the integration of spatially reference data in a spatially reference data in a problem solving environment.problem solving environment.

• A GIS also includes operating A GIS also includes operating personnel and the data that personnel and the data that go into the system.go into the system.

Components of a GISComponents of a GIS

Geographic Information System: Geographic Information System: intuitive descriptionintuitive description

• A map with a database A map with a database behind it.behind it.

• A virtual representation of A virtual representation of the real world and its the real world and its infrastructure. infrastructure.

• A consistent “as-built” of the A consistent “as-built” of the real world, natural and real world, natural and manmademanmade

Which is Which is • queriedqueried to support to support on-going on-going

operationsoperations • summarized summarized to support to support

strategic decision making strategic decision making and policy formulationand policy formulation

• analyzedanalyzed to support to support scientific scientific inquiryinquiry

GIS System Architecture and GIS System Architecture and ComponentsComponents

Data Input

Query InputGeograph

ic Database

Output: Display

and Reporting

Transformation

and Analysis

Knowledge Base for GISKnowledge Base for GIS

GISApplication Area:public admin.planninggeologymineral explorationforestrysite selectionmarketingcivil engineeringcriminal justicesurveying

Computer Science:graphicsvisualization databasesystem administrationsecurity

Geographyand related:cartographygeodesyphotogrammetrylandformsspatial statistics.

The convergence of technological fields and traditional disciplines.

Air Photos

Streets

Buildings

Components of a GISComponents of a GIS

GIS

People

Software

Hardware

Procedures

Sources of Input DataSources of Input Data

• Global Positioning System (gps)Global Positioning System (gps)– a system of earth-orbiting satellites which a system of earth-orbiting satellites which

can provide precise (100 meter to sub-cm.) can provide precise (100 meter to sub-cm.) location on the earth’s surface (in lat/long location on the earth’s surface (in lat/long coordinates or equiv.)coordinates or equiv.)

• Remote SensingRemote Sensing– Use of satellites or aircrafts to capture Use of satellites or aircrafts to capture

information about the earth’s surfaceinformation about the earth’s surface– Digital images a key product (map accurate Digital images a key product (map accurate

digital photos)digital photos)

Properties of Real World Properties of Real World Geographic InformationGeographic Information

• LocationLocation• Attributes

• Spatial Relationships

Geographic ObjectsGeographic Objects

• So the question So the question arises: “How do we arises: “How do we represent an object represent an object in space with a in space with a computer?”computer?”– An An objectobject is any is any

geographically geographically referenced entityreferenced entity• Lake, river, road, Lake, river, road,

country, sampling country, sampling site, etc.site, etc.

Outline for The RemainingOutline for The Remaining

• Three steps are involved in order to Three steps are involved in order to go from the real world geographic go from the real world geographic object to geographic object on the object to geographic object on the computercomputer1.1. Representations of Geographic RealityRepresentations of Geographic Reality

2.2. Linking Attributes to Geographic Linking Attributes to Geographic RepresentationRepresentation

3.3. Spatial Relationships between Spatial Relationships between Geographic RepresentationsGeographic Representations

1. Representations of 1. Representations of Geographic Reality: The Geographic Reality: The Data Model ApproachData Model Approach

Data ModelsData Models• Allows the Allows the geographic featuresgeographic features in in real real

world locationsworld locations to be digitally to be digitally represented and stored in a database so represented and stored in a database so that they can be abstractly presented in that they can be abstractly presented in map map (analog) form, and can also be (analog) form, and can also be worked with and worked with and manipulatedmanipulated to address to address some some problem problem Two common methods Two common methods are used:are used:– Vector data modelVector data model– Raster data modelRaster data model

Vector Data ModelVector Data Model

• Abstract spatial Abstract spatial featuresfeatures– PointPoint– LineLine– Area (polygon)Area (polygon)

• Record coordinatesRecord coordinates• Good for Good for

representing clearly representing clearly defined objectsdefined objects

• Spatial relationships Spatial relationships can be definedcan be defined

Point

Line

Area or Polygon

The Vector GIS Model: examplesThe Vector GIS Model: examples

roads

hydrology

topography

Here we have three layers or themes: --roads, --hydrology (water), --topography (land elevation)They can be related because precise geographic coordinates are recorded for each theme.

longitude

latitu

de

longitude

longitude

latitu

de

latitu

de

Layers are comprised of two data types•Spatial data which describes location (where)•Attribute data specifying what, how much, when

All geographic data has 4 properties: projection, scale, accuracy and resolution

Raster Data ModelRaster Data Model• Regular grid of cellsRegular grid of cells

– Each cell represents an Each cell represents an area on the groundarea on the ground

– Spatial resolutionSpatial resolution

• Value assigned to cell Value assigned to cell represents attributerepresents attribute– Land coverLand cover– ElevationElevation

• Satellite imagesSatellite images• Good for representing Good for representing

continuously continuously changing attributeschanging attributes

0 1 2 3 4 5 6 7 8 90 R T1 R T2 H R3 R4 R R5 R6 R T T H7 R T T8 R9 R

Real World

Vector RepresentationRaster Representation

Concept of Vector and Raster

line

polygon

point

Street Network layer: lines Land Parcels layer: polygons

Raster (image) Layer

VectorLayers

Layers

Projection: State Plane, North Central Texas Zone, NAD 83Resolution: 0.5 meters Accuracy: 1.0 metersScale: see scale bar0 1500 3000 Feet

Overlay based on Common Geographic Location

LocationLocation

• Absolute locationsAbsolute locations– Described by coordinate systemDescribed by coordinate system

• geographicgeographic• projectedprojected

• Relative locationsRelative locations– Described through a relationship Described through a relationship

between objects.between objects.

a. Geographic Coordinate a. Geographic Coordinate SystemsSystems

• Reference system for curved surface of earth

• Network of intersecting lines (graticule)

• Longitude

• Latitude

• The starting point is The starting point is defined at the defined at the intersection of equator intersection of equator and primary meridian.and primary meridian.

b. Projected Coordinate b. Projected Coordinate SystemSystem

• Reference system for features on a flat (projected) surface

• Cartesian coordinate system with designated origin

• Many different projected coordinate systems– Ex. UTM

Map ProjectionsMap Projections

• Projection of round earth Projection of round earth onto flat surfaceonto flat surface

• CommonCommon– Transverse MercatorTransverse Mercator– AlbersAlbers– RobinsonRobinson

– PlanarPlanar

– ConicalConical– CylindricalCylindrical

2. Linking Attributes to 2. Linking Attributes to Geographic Geographic

RepresentationRepresentation

AttributesAttributes• Non-spatial data associated with objectsNon-spatial data associated with objects• Information about the objects in our GISInformation about the objects in our GIS

– Land coverLand cover– Stream nameStream name– Flow rateFlow rate– Land ownerLand owner– AddressAddress

• Stored in tables that are linked with objectsStored in tables that are linked with objects– Polygon Attribute Table, Arc Attribute table, Point Polygon Attribute Table, Arc Attribute table, Point

Attribute TableAttribute Table

GIS as a DatabaseGIS as a Database

• Links attribute data to spatial dataLinks attribute data to spatial data• Spatially relates different objectsSpatially relates different objects

– TopologyTopology

• Allows for spatial and attribute Allows for spatial and attribute data queries and analysisdata queries and analysis

3. Spatial Relationships 3. Spatial Relationships between Geographic between Geographic

RepresentationsRepresentations

Spatial RelationshipsSpatial Relationships

• Geometric characteristics of Geometric characteristics of individual objectsindividual objects– Length, area, perimeter, shapeLength, area, perimeter, shape

• Spatial relationships between 2 or Spatial relationships between 2 or more objectsmore objects– Distance, direction, Distance, direction, topologytopology

• Spatial distribution of objectsSpatial distribution of objects– How objects are distributed in spaceHow objects are distributed in space

TopologyTopology• Topology is defined as the “spatial

relationships between adjacent or neighboring features.”

Fundamental GIS Fundamental GIS OperationsOperations

Fundamental GIS Fundamental GIS OperationsOperations

i.i. CaptureCapture

ii.ii. StoreStore

iii.iii. EditEdit

iv.iv. AnalysisAnalysis

v.v. DisplayDisplay

vi.vi. OutputOutput

i. Capturing Datai. Capturing Data

• DatabasesDatabases• GPSGPS• Remote SensingRemote Sensing• SensorsSensors• OthersOthers

ii. Data Storageii. Data Storage

• Through database management Through database management systemsystem

• Links attribute to spatial Links attribute to spatial informationinformation

iii. Data Editingiii. Data Editing

• Updating or correcting featuresUpdating or correcting features– shapes and attributesshapes and attributes

iv. GIS Analysisiv. GIS Analysis

• ““Visualizing and combining geographic Visualizing and combining geographic data to derive new information”data to derive new information”– Overlay maps, plotting population on a map etc.Overlay maps, plotting population on a map etc.

• QueriesQueries– attribute, locationattribute, location

• GeoprocessingGeoprocessing– Analysis of spatial relationships between Analysis of spatial relationships between

objects in a layer or objects in multiple layersobjects in a layer or objects in multiple layers– create new data setscreate new data sets

Data QueryData Query

• Queries are used to pull Queries are used to pull information out of a GISinformation out of a GIS

• You can think of a query as a You can think of a query as a question posed to the GISquestion posed to the GIS

• Replies with both spatial and Replies with both spatial and attribute informationattribute information

spatial -> attribute attribute -> spatial Spatial, attribute ->Which city is at or near

89oE 41oN?Where is Cambridge?

Find the areas between 20oN and 40oN with an annual precipitation above 800mm

ShapeSelect round features and describe them.

What is the shape of Walden Pond?

From a soil map, select those polygons that have soil type A and prolonged shapes.

OrientationSelect features with a NW->SE orientation and describe them.

What direction does the Nile River flow?

Show the land formations that are drumlins with a north-south orientation.

DistanceWhat city is 150 miles from Boston?

How far is Burlington from Nashua?

Select households that are within 1 mile from the asbestos factory and have children under 10 years old. Do any of these kids have asthma

DirectionWhat city is SW of Boston?

What direction is Burlington from Nashua?

Select the prairie that is downwind from this prairie and check its species structure.

TopologyWhat store neighbors the Coop?

Does Main border Masachusetts?

What is the average household income of all the neighbors of the Taylor family?

ClustersWhat are the clustered features?

Do auto dealers cluster together?

Select the retail stores that are clusted and determine their average revenues.

RelationshipsWhat type of plants grow on loamy soils?

Do Ponderosa Pines always grow on acidic soils?

Identify all major cities that attach to interstates and check their population.

Type of questionsType of spatial information

Location

Spatial Relationships

One Object

Multiple Objects

Many Objects

GeoprocessingGeoprocessing

• Any GIS operation that creates Any GIS operation that creates new datanew data

• SimpleSimple– Copy one data set and paste it Copy one data set and paste it

somewhere elsesomewhere else

• AdvancedAdvanced– Multiple operations on multiple data Multiple operations on multiple data

sets to create new, unique featuressets to create new, unique features

Advanced GeoprocessingAdvanced Geoprocessing

• Data extractionData extraction– creating a subset of creating a subset of

features from one data features from one data set based on the set based on the geographic extent of geographic extent of anotheranother

• OverlaysOverlays– combination of two or combination of two or

more data sets to more data sets to create new data setcreate new data set

• ProximityProximity– finding areas that are finding areas that are

near featuresnear features

v. vi. Display/Outputv. vi. Display/Output

• A GIS provides the tools to display A GIS provides the tools to display layers that allow the user to layers that allow the user to visually analyze geographic visually analyze geographic relationshipsrelationships

• Overlay different themesOverlay different themes• Design a map using data layers Design a map using data layers

and output in multiple formatsand output in multiple formats

Why Study GIS?Why Study GIS?• 80% of 80% of local governmentlocal government activities estimated to be geographically activities estimated to be geographically

basedbased– zoning, public works (streets, water supply, sewers), garbage collection, zoning, public works (streets, water supply, sewers), garbage collection,

land ownership and valuation, public safety (fire and police)land ownership and valuation, public safety (fire and police)• a significant portion of a significant portion of state governmentstate government has a geographical has a geographical

componentcomponent– natural resource managementnatural resource management– highways and transportationhighways and transportation

• businessesbusinesses use GIS for a very wide array of applications use GIS for a very wide array of applications– retail site selection & customer analysisretail site selection & customer analysis– logistics: vehicle tracking & routinglogistics: vehicle tracking & routing– natural resource exploration (petroleum, etc.)natural resource exploration (petroleum, etc.)– agricultureagriculture– civil engineeringcivil engineering and constructionand construction

• Military and defense Military and defense – Battlefield managementBattlefield management– Satellite imagery interpretationSatellite imagery interpretation

• scientific researchscientific research employs GIS employs GIS– geography, geology, botany geography, geology, botany – anthropology, sociology, economics, political scienceanthropology, sociology, economics, political science– Epidemiology, criminologyEpidemiology, criminology

The major areas of GIS applicationThe major areas of GIS application• Local GovernmentLocal Government

– Public works/infrastructure management (roads, water, sewer)Public works/infrastructure management (roads, water, sewer)– Planning and environmental managementPlanning and environmental management– property records and appraisal property records and appraisal

• Real Estate and MarketingReal Estate and Marketing– Retail site selection, site evaluation Retail site selection, site evaluation

• Public safety and defensePublic safety and defense– Crime analysis, fire prevention, emergency management, Crime analysis, fire prevention, emergency management,

military/defensemilitary/defense

• Natural resource exploration/extractionNatural resource exploration/extraction– Petroleum, minerals, quarryingPetroleum, minerals, quarrying

• TransportationTransportation– Airline route planning, transportation planning/modelingAirline route planning, transportation planning/modeling

• Public health and epidemiologyPublic health and epidemiology• The Geospatial IndustryThe Geospatial Industry

– Data /application development, programmingData /application development, programming

Examples of Applied GISExamples of Applied GIS• Urban Planning, Management & Urban Planning, Management &

PolicyPolicy– Zoning, subdivision planningZoning, subdivision planning– Land acquisitionLand acquisition– Economic developmentEconomic development– Housing renovation programsHousing renovation programs– Emergency responseEmergency response– Crime analysisCrime analysis– Tax assessmentTax assessment

• Environmental SciencesEnvironmental Sciences– Monitoring environmental riskMonitoring environmental risk– Modeling storm water runoffModeling storm water runoff– Management of watersheds, Management of watersheds,

floodplains, wetlands, forests, aquifersfloodplains, wetlands, forests, aquifers– Environmental Impact AnalysisEnvironmental Impact Analysis– Groundwater modeling and Groundwater modeling and

contamination trackingcontamination tracking• Political SciencePolitical Science

– RedistrictingRedistricting– Analysis of election resultsAnalysis of election results– Predictive modelingPredictive modeling

• Civil Engineering/UtilityCivil Engineering/Utility– Locating underground facilitiesLocating underground facilities– Designing alignment for freeways, transitDesigning alignment for freeways, transit– Coordination of infrastructure maintenanceCoordination of infrastructure maintenance

• BusinessBusiness– Demographic AnalysisDemographic Analysis– Market Penetration/ Share AnalysisMarket Penetration/ Share Analysis– Site SelectionSite Selection

• Education AdministrationEducation Administration– Attendance Area MaintenanceAttendance Area Maintenance– Enrollment ProjectionsEnrollment Projections– School Bus RoutingSchool Bus Routing

• Real EstateReal Estate– Neighborhood land pricesNeighborhood land prices– Traffic Impact AnalysisTraffic Impact Analysis– Determination of Highest and Best UseDetermination of Highest and Best Use

• Health CareHealth Care– EpidemiologyEpidemiology– Needs AnalysisNeeds Analysis– Service InventoryService Inventory

SummarySummary

• A GIS combinesA GIS combines– Spatial and attribute databaseSpatial and attribute database– Processing toolsProcessing tools– Graphic CapabilitiesGraphic Capabilities– UsersUsers

• Create a system of advanced Create a system of advanced spatial analysis for multiple usesspatial analysis for multiple uses

• Questions?Questions?