URBDP 498w Introduction to GIS in Planning

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URBDP 498wIntroduction to GIS in Planning

• Lecture 5
• Data Acquisition Georeferencing

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Plan for Today

• Lecture
• Review Exercise 2
• Data Acquisition
• Georeferencing
• Lab
• Start Exercise 3 (Due Next Tuesday)

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Data Acquisition

• Human Input
• Automated Data Entry
• Remote Sensing Imagery
• Global Positioning Systems (GPS)
• Address Geocoding

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Data AcquisitionHuman Input

• Digitizing Paper Maps
• Enter Features,
• Then Register to Coordinate System
• Typing Coordinates from Tabular Data
• Establish Coordinate System,
• Then Enter Feature Coordinate Data

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Data AcquisitionRemote Sensing

• Sources
• Space Shuttle, Satellites, Aircraft
• Types of Data
• Reflected Light (Photography)
• Infrared (Heat)
• LIDAR (Elevation)
• Land Cover (Using Spectral Signature
  Classification)

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Data AcquisitionRemote Sensing

• Processing
• Clean Data (Remove Noise)
• Improve Contrast and Information
• Convert Raster Data to Themes
• Classify Features
• Transfer to GIS

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Data AcquisitionAutomated Data Entry

• Data Processing Steps
• Scan as a Raster
• Thin Lines
• Vectorize
• Clean/Edit
• Add Topology
• Integrate to GIS

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Data AcquisitionGlobal Positioning Systems

• Field Surveys Using GPS Devices
• Coordinates and Human Input Fed Directly to GIS
• Interactive GPS Can Help
• Distinguish Between Discrete Features and
• Associate Attributes with Coordinates

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Data AcquisitionAddress Geocoding

• Identifies a Point Location Using a Street
  Address
• Requirements
• Street Network With Address Ranges as Attributes
• Geocoding Service Definition
• List of Addresses with Associated Non-Spatial
  Attributes
• Output
• Point Features with Associated Non-Spatial
  Attributes

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Georeferencing

• Identifying Locations on the Earth Using
  Locations on a Map or GIS
• Aspects of Georeferencing
• Coordinate Systems
• Datums
• Projections

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Georeferencing Coordinate Systems

• A Method of Location Objects on the Earths
  Surface
• Examples
• Global Coordinate System
• Cartesian Coordinate System

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Georeferencing Global Coordinate System

• Latitude y-coordinate

• Longitude x-coordinate

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Georeferencing Measuring Latitude
Side View

• Latitude Measures the Angular Distance from the
  Equator

North Pole(90 º N)
60 º N
60 º
Equator
South Pole(90 º S)
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Georeferencing Measuring Longitude
Top View

• Longitude Measures the Angular Distance from the
  Prime Meridian (Greenwich, UK)

135 º E
North Pole
Equator
135 º
70 º
70 º W
Prime Meridian (0 º)
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Georeferencing Measuring Latitude Longitude

• Measurement in Degrees, Minutes, Seconds
• 1 Degree 60 Minutes
• 1 Minute 60 Seconds
• 1 Degree 3600 Seconds
• Forms of Latitude Longitude
• DMS 135º45'23" N
• Decimal 135 45/60 23/3600 135.7564º N

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Georeferencing Global vs. Cartesian Coordinates

• Global
• Spherical
• Effect on Distances
• Variable Distances
• Effect on Areas
• Minimal Distortion

• Cartesian
• Planar
• Effect on Distances
• Constant Distances
• Effect on Areas
• High Distortion a Edges

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Georeferencing Datums

• Datums are Origin Points for Coordinate Systems,
  i.e. a Single Reference Point on the Surface of
  the Earth with the Coordinate Value of (0,0)
• Common Datums
• North American Datum 1927 (NAD27)
• North American Datum 1983 (NAD83)

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Georeferencing Projection

• The Process of Systematically Transforming
  Positions on the Earths Spherical Surface to a
  Flat Map While Maintaining Spatial Relationships

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Georeferencing Map Projection and Distortion

• For Geometric Properties Affected by Projection
• Shape or Angle
• Area
• Distance
• Direction
• All projections produce some distortion

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Georeferencing Projection Types and Effects

• Equal Area Projections
• Preserve Areas of Features
• Conformal Projections
• Preserve Shapes of Small Features
• Show Local Directions Correctly
• Equidistant Projections
• Preserve Distances to Places from One Point
• True Direction Projections
• Preserve Bearings either Locally or from Center
  of Map

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Georeferencing Geometric Models for Projection

• Conical
• Tangent along a Specific Latitude
• Cylindrical
• Tangent along Equator or a Longitude
• Planar/Azimuthal/Zenithal
• Tangent at a Single Point

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Georeferencing Common Projection Systems

• Universal Transverse Mercator (UTM)
• State Plane (SP)

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Projection SystemsUniversal Transverse Mercator

• Series of Cylindrical Projections, Tangential to
  a Longitude Line
• 60 Zones, One Every 6 Degrees Longitude
• Each Zone
• Width is 6º in Longitude
• Height is from 80º S to 84º N in Latitude

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Projection SystemsState Plane

• Planar Projection
• Tangent at Different Points for Each State
• Most States Have Two or More Zones