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Basic Concepts in GIS

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Title: Basic Concepts in GIS


1
Basic Concepts in GIS
  • Eric J. Howard
  • GIS Analyst, Center for Embedded Networked
    Sensing
  • 4/16/2008
  • CS219

2
Overview
  • What is GIS?
  • Spatial Analysis
  • GIS System Architecture, Overview
  • Issues of Scale
  • VTTI
  • Roanoke Valley MPO Stud
  • ShenAir
  • Conclusion

3
What is GIS
  • Geographic Information Systems
  • or ..
  • Geographic Information Science

4
What is GIS?
  • A system for capturing, storing, checking,
    integrating, manipulating, analysing and
    displaying data which are spatially referenced to
    the Earth. This is normally considered to involve
    a spatially referenced computer database and
    appropriate applications software
  • Chorley Report, 1987

5
What is GIS?
  • Hardware
  • Software
  • Data
  • People
  • Methods

6
Spatial Analysis
You Are Here!
Do two items occupy the same space? What is the
spatial distribution of this species? How does
this person move through their neighborhood? What
is the best route to this location? ----Not a new
idea------
7
Spatial Analysis
Cholera Epidemic in Soho, London - 1854
  • 500 deaths within 200 yards of the Broad St
    public water pump
  • When the pump handle was removed, no new cases
    were diagnosed in that Street.
  • Dr. Snow proved that the pump had been the
    source of the those cases and that the cholera
    was carried in the contaminated water

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9
GIS System Architecture Overview
Data Collection GPS R.S. Digitizing Survey Inst.
Data Viz. ArcGIS Google Earth Google
Maps Openlayers GRASS
Data Storage Shapefiles ArcSDE PostGIS
Data Processing ArcGIS PostGIS QGIS GRASS
10
Data Collection
  • Global Positioning Systems
  • Remote Sensing Applications
  • Various Platforms
  • Image / Raster based
  • Digitizing
  • Survey Instruments / Dead Reckoning

11
Data Storage
  • Position In Space Relationships
  • Most databases now support some type of spatial
    data types
  • OGC vs. ArcSDE

12
Data Storage
  • Projection Systems
  • Cylindrical
  • Conical
  • Planer

http//info.wlu.ca/wwwgeog/special/geomatics/html
/arcprojections.htm
13
Data Processing / Analysis
  • Vector Data Types
  • Basic Spatial Relationship (intersections,
    unions, etc..)
  • Flow / Movement
  • Network Analysis
  • Geo spatial statistics

14
Data Processing / Analysis
  • Raster
  • Land-cover Classification
  • Concentration
  • Flow / Movement
  • Geo spatial statistics

15
Issues of Scale
  • Operational Scale
  • Level in which processes of interest occur
    (contaminate transport)
  • Geographic Extent
  • Size of study area (local, regional, global)
  • Spatial Resolution / Cartographic Scale
  • Detail / Granularity of analysis and display
    (124,000)

16
Issues of Scale
17
Scale Concepts
18
VTTI Regional pedestrian activity measurement
study
Purpose Determine the usability of wearable GPS
and cell phone technologies to collect pedestrian
movement data.
19
VTTI Regional pedestrian activity measurement
study
  • Project Team
  • Urban Planning
  • Systems Engineering
  • Electrical Engineering
  • Public Administration
  • Statistics

20
VTTI Regional pedestrian activity measurement
study
21
VTTI Regional pedestrian activity measurement
study
22
VTTI Regional pedestrian activity measurement
study
The Trackstick
23
VTTI Regional pedestrian activity measurement
study
  • Lessons learned
  • This is technically challenging (especially from
    a Planner standpoint)
  • Results where promising but still had a to go for
    consistent results
  • Large amount time spent on data manipulation

24
Roanoke Valley MPO Transportation Mode Choice
Model
  • Purpose
  • Create a Transportation Mode Choice Model for the
    Roanoke MPO
  • Determine if regional development patterns and
    neighborhood characteristics can improve the
    model results.

25
Roanoke Valley MPO Transportation Mode Choice
Model
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27
Roanoke Valley MPO Transportation Mode Choice
Model
  • Uqit ßqxqit eqit
  • Where,
  • Uqit utility that an individual (q) associates
    with an alterative (i) choice at a specific
    occasion (t)
  • xqit a vector of observed variable (including
    alternative specific constants)
  • ßq corresponding coefficient vector that may
    vary over individuals but does not vary across
    alternatives or time
  • eqit assumed to be identical, independent, and
    evenly distributed.

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31
Roanoke Valley MPO Transportation Mode Choice
Model
32
Roanoke Valley MPO Transportation Mode Choice
Model
33
Roanoke Valley MPO Transportation Mode Choice
Model
  • Lessons learned
  • Sending out paper surveys takes a long time
  • Self reporting results leads to underreporting of
    trip
  • People in Roanoke tend to drive

34
ShenAir Initiative
  • Created as a result of Shenandoah Valley Early
    Action Compact Agreement.
  • Government and University alliance to provide a
    regional science based response to air quality
    issues.

35
ShenAir Initiative
  • Project Team
  • Meteorology
  • Climatology
  • Mechanical Engineering
  • Atmospheric Chemistry
  • Computer Science
  • Urban Planning
  • Local Government
  • Local Environmental Organizations

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37
ShenAir Initiative
38
ShenAir Initiative
  • Complete land cover classification for the entire
    state
  • Calculate error measure for classification from
    aerial photography
  • Calculate exposure rates for built areas

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42
Conclusion Tips for successful maps
  • Should have
  • North Arrow
  • Legend
  • Descriptive Title
  • Metadata
  • Date Published
  • Scale

43
Conclusion Tips for successful maps
  • Use simple and clean symbols
  • Contrasting colors to make statements
  • Provide context information
  • Remember who your audience is
  • .and try to avoid plastic looking maps.

44
Possible Campaigns
  • Journey to Work
  • Landmarks / Community Identity / Asset-mapping
  • Time-Activity Spaces
  • Physical Activity / Caloric Expenditure

45
Thanks!
ejhoward_at_cens.ucla.edu
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