Basic Concepts in GIS

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Basic Concepts in GIS

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

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Overview

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

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What is GIS

• Geographic Information Systems
• or ..
• Geographic Information Science

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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

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What is GIS?

• Hardware
• Software
• Data
• People
• Methods

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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------
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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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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
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Data Collection

• Global Positioning Systems
• Remote Sensing Applications
• Various Platforms
• Image / Raster based
• Digitizing
• Survey Instruments / Dead Reckoning

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Data Storage

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

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Data Storage

• Projection Systems
• Cylindrical
• Conical
• Planer

http//info.wlu.ca/wwwgeog/special/geomatics/html
/arcprojections.htm
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Data Processing / Analysis

• Vector Data Types
• Basic Spatial Relationship (intersections,
  unions, etc..)
• Flow / Movement
• Network Analysis
• Geo spatial statistics

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Data Processing / Analysis

• Raster
• Land-cover Classification
• Concentration
• Flow / Movement
• Geo spatial statistics

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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)

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Issues of Scale
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Scale Concepts
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VTTI Regional pedestrian activity measurement
study
Purpose Determine the usability of wearable GPS
and cell phone technologies to collect pedestrian
movement data.
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VTTI Regional pedestrian activity measurement
study

• Project Team
• Urban Planning
• Systems Engineering
• Electrical Engineering
• Public Administration
• Statistics

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VTTI Regional pedestrian activity measurement
study
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VTTI Regional pedestrian activity measurement
study
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VTTI Regional pedestrian activity measurement
study
The Trackstick
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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

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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.

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Roanoke Valley MPO Transportation Mode Choice
Model
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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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Roanoke Valley MPO Transportation Mode Choice
Model
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Roanoke Valley MPO Transportation Mode Choice
Model
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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

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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.

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ShenAir Initiative

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

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ShenAir Initiative
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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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Conclusion Tips for successful maps

• Should have
• North Arrow
• Legend
• Descriptive Title
• Metadata
• Date Published
• Scale

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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.

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Possible Campaigns

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

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Thanks!
ejhoward_at_cens.ucla.edu