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Lecture 3. How does GIS work. How does GIS work?. Maps are stored in computers Databases and Tables Geometry Attributes. How does GIS work?. Categories of reality are divided into layers Countries, States, Cities Parcels of land ownership Roads , Rivers, Lakes, Buildings

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lecture 3

Lecture 3

How does GIS work

how does gis work
How does GIS work?

Maps are stored in computers

Databases and Tables

Geometry

Attributes

how does gis work1
How does GIS work?

Categories of reality are divided into layers

Countries, States, Cities

Parcels of land ownership

Roads, Rivers, Lakes, Buildings

ZIP codes

how does gis work2
How does GIS work?

Layers are made up of points, lines, or polygons

Cities – points

Roads – lines

Counties – polygons

slide5

Drawing maps

Points, lines, polygons, and text

Work

Main Street

Mall

Construction

Home

slide6

Change street layer color and thickness

Work

Main Street

Mall

Construction

Home

slide7

Turn Streets layer off

Work

Main Street

Mall

Construction

Home

levels of geography
Levels of geography
  • Country
  • State
  • County
  • City

DEMO

http://www.marshallco.org/www/maps/images/50seregexpl.jpg

levels of geography1
Levels of geography
  • Block group

http://www2.lib.udel.edu/subj/maps/internet/dedo/nnccinc.htm

levels of geography2
Levels of geography
  • ZIP code

http://cssr.berkeley.edu/cwscmsreports/maps/showEntriesCountymap.asp?page=Ora

levels of geography3
Levels of geography
  • Parcel
  • Buildings
  • Houses
gis links attribute and spatial data
GIS links attribute and spatial data
  • Each layer has a database table
  • Each map feature has one record in the table
  • The table has attributes about the features
one to one layer and table
One to one: layer and table
  • One to one: map feature and record
is your data spatial
Is your data spatial?
  • >80 percent of all data has location
  • “What’s your ZIP code”
before gis just pens and paper
Before GIS Just Pens and Paper

http://www.census.gov/pubinfo/www/photos/img/lowres/Hist08l.jpg

slide27

GIS Power

  • Just a database
  • Tools
  • Analysis
  • GIS Science and Geography
  • Geo Statistics
  • Aids in decision making
    • Remember “Maps Communicate”
which 8 of 7000 stores to close
Which 8% of 7000 stores to close?

http://money.cnn.com/news/specials/storysupplement/starbucks_closings/CA.html

5 steps to gis analysis1
5 steps to GIS analysis
  • Frame the question
  • Get the data
  • Choose analysis method
  • Process the data
  • Look at the results
slide33

Frame the question

  • Where can we put a garbage dump?
slide34

Frame the question

  • Where can we put a garbage dump?
    • Not on bad soil
    • Out of the city
    • Not in a park
    • Not in a protected area like a forest
    • More?
slide35

Get the data

  • Color in the unacceptable areas
  • Can’t locate in dark areas

SOILS

URBAN

PARKS

FOREST

slide36

Choose analysis method

  • OVERLAY the layers on top of each other

URBAN

PARKS

SOILS

FOREST

slide37

Process the data

  • Color in the unacceptable areas

SOILS

URBAN

PARKS

Solution map

FOREST

slide39

Check out other similar projects

http://www.ruralgis.org/conference/2004proceedings/thurs/session4/thurs_4_1_00.pdf

slide40

Map Overlay

  • But what about the protected rats?

Rats

SOILS

URBAN

PARKS

FOREST

Solution map

before gis paper
Before GIS - Paper
  • Computers speed the process
  • Databases hold more information than paper
  • Why GIS?
    • Faster
    • Cheaper
    • Easier
    • More

http://www.census.gov/pubinfo/www/photos/img/lowres/Hist08l.jpg