IntroductionIntroductionToToGISGIS

with Gary Johnsonwith Gary Johnson

WHAT IS GIS ?

What examples did you find ?

G I SG I SAn organized collection ofAn organized collection of

computer hardware, software,computer hardware, software,geographic data, and personnelgeographic data, and personneldesigned to efficiently capture,designed to efficiently capture,

store, update, manipulate,store, update, manipulate,analyze, and display all formsanalyze, and display all formsof geographically referencedof geographically referenced

information.information.

GG

II

SS

GGeographiceographic: A locationlocation somewhere on , above, or below the Earth.(Spatial data)

IInformationnformation:Qualities or attributesattributes of a geographic location.(non-Spatial data)

SSystemystem:ToolsTools used to develop,query, and displaygeographic information.

G I SG I SWhat is it ?What is it ?

It is a process which looks at the relationships

between layerslayers of geographic information

G I SG I Sis a process

which looks at the relationshipsof layers by asking

questionsquestions questionsquestions questions:questions:Who is within a distance of...Who is within a distance of...

What would happen if...What would happen if...When was the last time...When was the last time...

Where is a specific location of...Where is a specific location of...How far from one location to another...How far from one location to another...

How many occurrences of an event are How many occurrences of an event are within a distance of a location.within a distance of a location.

Examples of GIS questions askedExamples of GIS questions asked

Desert Game RangeDesert Game RangeWhat is the total area of industrial minerals ?What is the total area of industrial minerals ?

Potential Radon HazardPotential Radon HazardWhere are the potential radon hazards ?Where are the potential radon hazards ?

Earthquake ScenarioEarthquake ScenarioWhat would happen in Reno if a 7.1What would happen in Reno if a 7.1 earthquake happened on theearthquake happened on the Carson Valley Fault rangeCarson Valley Fault rangeEarthquake EventEarthquake Event

How many events happened in 1976How many events happened in 1976

Layers of geographicallyreferenced data

An organized collection of computer hardwaresoftware, geographic data, and personnel designedto efficiently capture, store, update, manipulate,analyze, and display all forms of geographicallyreferenced information.

WH

AT

IS A

G

IS ?

Key Terms

ARC

Node

Vertex

Pseudonode

Danglingnode

Label

User-ID

Tic

A layerlayer is a theme of various featuresfeatures:

LAYERSLAYERS

Locations (points)(points) + ++

Lines (arcs)(arcs)

Areas (polygons)(polygons)

Images (raster)(raster)TIFF DEM Grids

An x,y valueAn x,y value

A series of x,y locationsA series of x,y locations

A closed series of x,y locationsA closed series of x,y locations

VE

CT

OR

RA

ST

ER

G I SG I SWhat is it ?What is it ?

It is a process which looks at the relationships

between layerslayers of geographic information

Topology (Relationships)

A mathematical procedure for explicitly defining spatial relationships

Three major topological concepts:Three major topological concepts:

Arcs connect to each other at nodes Arcs connect to each other at nodes ((connectivityconnectivity))

Arcs that connect to surround an area define a polygon Arcs that connect to surround an area define a polygon ((area definitionarea definition))

Arcs have direction and left and right sides Arcs have direction and left and right sides ((contiguitycontiguity))

Feature Class - PointsFeature Class - Points

An x,y locationAn x,y location

X

Y

X

Y

Feature Class - LineFeature Class - Line

A series of x,y locationsA series of x,y locations

Feature Class - Area (polygons)Feature Class - Area (polygons)

A series of x,y locations that are closedA series of x,y locations that are closed

X

Y

Arcs connect to each other at nodes.

10

Arcs that connect to surround an area define a polygon

Arcs have direction and left and right sides

Announcements:Announcements:

ArcView or ArcGIS is availableArcView or ArcGIS is available(somewhere around)(somewhere around)

$300.00 for each module$300.00 for each module

Call E.S.R.I. 1-800-447-9778Call E.S.R.I. 1-800-447-9778you will need to fax your class scheduleyou will need to fax your class schedule