An Introduction to GIS and GPS Technology

1
An Introduction to GIS and GPS Technology

• Bo Shen
• March 5, 2004

2
Overview

• What is GIS?
• GIS Application
• GIS Data
• GIS Technology(ArcGIS)
• What is GPS?
• What does the GPS do?
• How it works
• Application with GIS and GPS
• Pocket Street
• Automated Vehicle Location System

3
A definition of GIS

• GIS (-Geographic Information Systems) is a
  computer software, hardware and data, and
  personnel to help manipulate, analyze and present
  information that is tied to a spatial location.
• spatial locationusually a geographic location

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What is GIS

• Different layers
• Typically a GIS is used for handling maps of one
  kind or another.
• These might be represented as several different
  layers where each layer holds data about a
  particular kind of feature.
• Each feature is linked to a position on the
  graphical image of a map
• Smart Maps
• linking database to maps.

5
GISOne example with Five Data Layers
6
Maps and Database are Interactive
7
Some ways of using GIS Technology

• Wherever Spatial Data Analysis is Needed
• Emergency Services Fire Police
• Environmental Monitoring Modeling
• Business Site Location, Delivery Systems
• Industry Transportation, Communication,
• Mining, Pipelines, Healthcare
• Government Local, State, Federal, Military
• Education Research, Teaching Tool,
  Administration

8
GIS Application

• In the past,
• Survey data was first read into a computational
  program, where errors are eliminated and point
  coordinates reduced.
• The reduced data is then transferred to a CAD
  program and complemented with construction
  elements
• Finally the data is transferred to a central
  system.

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GIS Application Today

• Todays modern systems allow data to be
  transferred directly to the GIS database.
• All information is immediately available for
  further processing such as correcting errors,
  performing calculations, etc.

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GIS Application Today

• Handheld GIS computer system
• GPS based interface
• Commercial GIS data sources
• Internet based data
• server

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Data flow For GIS Application
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Data Sources for GIS

• Digitized and Scanned Maps
• purchased, donated, free (Internet)
• created by user
• DataBases Tables of data
• GPS Global Positioning System
• accurate locations
• Remote Sensing
• Aerial Photography

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Data Store

• Vector Formats Discrete representations of
  Reality
• give specific spatial locations explicitly
• geographic space is continuous, not quantized
• attributes are stored separately from locations

• Raster Formats use square cells to model
  reality
• Matches hardware nicely
• Reduced spatial precision
• Large storage requirements

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Raster Data Compression

• Run-length encoding
• Chain codes
• Quadtrees

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Run-length Encoding
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Chain Codes
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Quadtree

• Quadtree starts with entire map divided into
  quadrants.
• Each quadrant is subdivided until it is
  homogeneous.
• Four quadrants are NW, NE, SW, and SE
• smallest unit is a grid cell

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Data Query

• Identifying specific features

• Identifying features based on conditions
• Florida counties with a
• population greater than
• 300,000

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Data Analysis
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Data Display
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Data Output
22
GIS based on many disciplines and technologies

• Geography
• Cartography
• Computer science
• Mathematics
• Statistics
• Remote sensing/GPS/surveying
• Telecommunications/Internet
• Operations research/information science

23
GIS Technology Software

• GIS software provides the functions and tools
  needed to store, analyze, and display information
  about places.
• The key components of GIS software are
• Tools for entering and manipulating geographic
  information such as addresses or political
  boundaries
• A database management system (DBMS)
• Tools that create intelligent digital maps you
  can analyze, query for more information, or print
  for presentation
• An easy-to-use graphical user interface (GUI)
• Major GIS software
• ARCGIS (ArcView 8.1)

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ArcView GIS Data Sets

• The GIS Data set used
• Shape file
• Consisting of
• Shape file (.shp)
• Shape Index (.shx)
• Database table (.dbf)
• Additional files may be present and required as
  well

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ArcView GIS

• Three Principles Modules
• ArcCatalog
• ArcMap
• ArcToolbox

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ArcCatalog

• A window into your database
• Browse your data
• Manage your data
• Create and view data
• documentation

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ArcMap

• Primary display application
• Perform map-based tasks
• Displaying
• Editing
• Querying
• Analyzing
• Charting
• Reporting

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ArcToolbox

• Major functions
• Data management, analysis, and conversion
• Variation of tools between ArcGIS products

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GIS Resources

• GIS Information
• University of California Berkeley, GIS
  libraryhttp//sunsite.berkeley.edu/GIS/gisnet.htm
  l Spatial Odyssey, University of Maine, GIS
  Literature Databasehttp//wwwsgi.ursus.maine.edu/
  
• GIS Software Sources
• Environmental Systems Research Institute, Inc.
  (ESRI)http//www.esri.com/
• MapInfohttp//www.mapinfo.com/
• Intergraph http//www.intergraph.com/dynamicdefau
  lt.asp
• AutoCADhttp//usa.autodesk.com/adsk/servlet/home?
  siteID123112id129446
• Clark Labs http//www.clarklabs.org/

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Global Positioning System (GPS)

• The Global Positioning System (GPS)
• is a satellite-based navigation system made
  up of a network of 24 satellites placed into
  orbit by the U.S.Department of Defense.
• GPS satellites
• 24 Satellites in 6 planes, each plane has 4
  satellites
• These space vehicles (SVs) send radio signals
  from space.

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What does the GPS do

• Satellite signals can be processed in a GPS
  receiver.
• GPS receiver will show your EXACT location on the
  Earth (latitude and longitude)
• Helps you find your way to a specified location
• Lets you know what direction you are heading and
  how fast you are going

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GPS- How it works

• Measuring the distance from a satellite by
  measuring travel time of radio signals seconds
• Distance speed of light latency in time
• Four GPS satellite signals are used to compute
  positions in three dimensions and the time offset
  in the receiver clock.

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GPS- How it works

• Given 1 satellite

• We can locate our position on the surface of a
  sphere

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GPS- How it works

• Given 2 satellites

• We can locate our position on the intersection of
  2 spheres (a circle)

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GPS- How it works

• Given 3 satellites

• We can locate our position on the intersection of
  3 spheres (2 points)

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GPS-How it works

• Given 4 satellites

• We can locate our position on the intersection of
  4 spheres (1 point). The point should be located
  on the earths surface

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GPS- How it works

• The GPS receiver compares the time a signal was
  transmitted by a satellite with the time it was
  received. The time difference tells the GPS
  receiver how far away the satellite is.
• With four or more satellites in view, the
  receiver can determine the user's 3D position
  (latitude, longitude and altitude).

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Pocket Streets- an example with GPS and GIS

• Pocket Streets offers exciting
• features such as street-smart
• mapping, map customization,
• GPS and Microsoft Outlook
• integration.
• With Pocket Streets on your
• Pocket PC, you will take a smart
• map with you wherever you go.

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Pocket Streets- an example with GPS and GIS

• Download the map for the city.
• Connect the GPS receiver to
• Pocket PC.
• Choose "Track Position" from the
• GPS menu to show your current
• position on the map.
• The position moves when you move.

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Pocket Streets- an example with GPS and GIS

• Tap-and-Hold on either a Contact with an address,
  or a Calendar appointment that has an address in
  the location.
• Choose "Find On Map" from the pop-up menu to
  show the location in Pocket Streets.

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Pocket Streets- an example with GPS and GIS

• With GPS, you can get your
• Current Location.
• From the outlook, you get the
• Address of your contacts and GIS
• Will find the location on the map.
• So, Pocket Street will guide you
• to your destination

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Automated Vehicle Location System

• Where is the bus
• What direction is
• the bus traveling to
• What is the travel
• speed
• Where is stop
• How long is the stop

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Automated Vehicle Location System

• How Do GPS , GIS and AVL Relate?
• GPS receiver calculates its position (latitude
  and
• longitude) and record the information at fixed
  time
• interval
• GPS transmitter transmits location and vehicle
• dynamic data to control center at prescribed
  interval
• Control center system process data accoding to
  customer specifications
• GIS Software display filtered information on the
  screen with map layer

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Automated Vehicle Location System
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Conclusions

• GPS can show your EXACT location on the Earth
  (latitude and longitude)
• GIS provides several different map layers where
  each layer holds data about a particular kind of
  feature related to spatial data.
• Using GIS and GPS we can capture, management,
  analysis, modeling and display geographically
  referenced data for decision making. It is a way
  in which to begin to represent and model the real
  world.