IntroductionToGIS with Gary Johnson

WHAT IS GIS ? What examples did you find ?

G I S An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.

G I S G eographic G eographic: location A location somewhere on, above, or below the Earth. (Spatial data) I nformation I nformation: attributes Qualities or attributes of a geographic location. (non-Spatial data) S ystem S ystem: Tools Tools used to develop, query, and display geographic information.

G I S What is it ? It is a process which looks at the relationships layers between layers of geographic information

G I S is a process which looks at the relationships of layers by asking questionsquestionsquestions: Who is within a distance of... What would happen if... When was the last time... Where is a specific location of... How far from one location to another... How many occurrences of an event are within a distance of a location.

Examples of GIS questions asked Desert Game Range What is the total area of industrial minerals ? Potential Radon Hazard Where are the potential radon hazards ? Earthquake Scenario What would happen in Reno if a 7.1 earthquake happened on the earthquake happened on the Carson Valley Fault range Carson Valley Fault range Earthquake Event How many events happened in 1976

Layers of geographically referenced data

An organized collection of computer hardware software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information. WHAT IS A GIS ?

Key Terms ARC Node Vertex Pseudo node Dangling node Label User-ID Tic

layer A layer is a theme of features various features: LAYERS Locations(points) Lines(arcs) Areas (polygons) Images(raster) TIFFDEMGrids An x,y value A series of x,y locations A closed series of x,y locations VECTOR RASTER

G I S What is it ? It is a process which looks at the relationships layers between layers of geographic information

Topology (Relationships) A mathematical procedure for explicitly defining spatial relationships Three major topological concepts: Arcs connect to each other at nodes (connectivity) Arcs that connect to surround an area define a polygon (area definition) Arcs have direction and left and right sides (contiguity)

Feature Class - Points An x,y location X Y

X Y Feature Class - Line A series of x,y locations

Feature Class - Area (polygons) A 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: ArcView or ArcGIS is available (somewhere around) $ for each module Call E.S.R.I you will need to fax your class schedule