GIS Lecture 5

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GIS Lecture 5 Importing Spatial and Attribute
Data
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Outline

• GIS Data Sets
• Map Projections
• Coordinate Systems
• GIS Data Sources

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GIS Data Sets
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GIS Data Sets

• ArcInfo Coverages
• ArcView Shapefiles
• CAD Files
• Aerial Photos
• Event Files

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ArcInfo
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ArcInfo Coverages
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ArcINFO Coverages in ArcMap
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Polygon Coverages

• Area and perimeter automatically calculated

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Polygon Coverages

• Polygons share borders

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Line Coverages

• Length automatically calculated

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Point Coverages
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ArcInfo Coverages

• Advantages
• Many feature types
• Shared borders
• Automatic Area/Perimeter/Length fields
• Disadvantages
• Cannot edit in ArcMap

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ArcInfo Export files

• .e00 export exchange file
• ArcCatalog translates into ArcGIS
• Creates coverages

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ArcView Shape Files

• Advantages
• heads-up digitizing and editing
• less storage/rapid display
• can export to CAD
• Disadvantages
• one feature type
• no area or perimeter with new shapefiles

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ArcView Shape Files

• From 3 to 5 Files
• .shp - stores feature geometry
• .shx - stores index of features
• .dbf - stores attribute data
• .sbn and .sbx - store additional indices

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ArcView Shapefiles
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CAD Files

• Why CAD Drawings?
• Better Precision for Digitizing
• .DWG / .DXF

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Adding CAD Files
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CAD Files in ArcMap
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Aerial Images

• Combining Grid and Vector Maps

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Event Files

• X,Y Coordinates

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Event Files
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Event Files
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Map Projections
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Map Projections and Distortion

• Map projections produce distortion in one or more
  spatial properties
• Shape, area, distance, and direction
• Specific projections eliminate or minimize
  distortion

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Distortion Examples
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Mercator Projection Distortion
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Robinson Projection Distortion
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Projection Important

• Measurements used to make important decisions
• Comparing shapes, areas, distances, or directions
  of map features
• Feature and image themes are aligned

New York
New York
Los Angeles
Los Angeles
Projection MercatorDistance 3,124.67 miles
Projection Albers Equal AreaDistance 2,455.03
miles
Actual distance 2,451 miles
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Projection not Important

• Business applications
• Not of critical importance.
• Concerned with the relative location of different
  features
• On large scale maps - street maps
• Distortion may be negligible
• Map covers only a small part of the Earth's
  surface.

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Coordinate Systems
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Coordinate Systems

• Spherical/Polar
• Geographic Coordinate System
• Rectangular
• State Plane
• UTM

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Geographic Coordinate System

• Latitude and Longitude
• Census Bureau TIGER files

Geographic Coordinate System Grid
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Longitude Meridians
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Latitude Parallels
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Origin

• Longitude (prime meridian)

0

• Latitude (equator)

0
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Coordinates
Pittsburgh
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-80
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Pittsburghs Point

• Degrees, Minutes, and Seconds (DMS)
• 40262N latitude
• -80058W longitude
• Decimal Degrees (DD)
• 1 degree 60 minutes,
• 1 minute 60 seconds
• 40262
• 40 26/60 2/3600 40 .43333
  .00055
• 40.434

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Translated to Distance

• World circumference through
• the poles is 24,859.82 miles,
• so for latitude
• 1 24,859.82/360 69.1 miles
• 1 24,859.82/(36060) 1.15 miles
• 1 24,859.825,280/(3603600) 101 feet
• Length of the equator is 24,901.55 miles

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Rectangular Coordinate Systems

• State Plane Coordinates
• Local Governments
• UTM
• US Military

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State Plane Coordinate System

• Established by the U.S. Coast and Geodetic Survey
  (now the National Ocean Survey)
• At least one for each state
• Rectangular (x,y) coordinates
• 125 zones, following state and county boundaries
  each with its own projection
• Lambert conformal projection for zones with
  east-west extent
• Transverse Mercator projection for zones with
  north-south extent
• Cannot have zones joined to make larger regions

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Rectangular Coordinates
Has all positive Cartesian coordinates in feet,
called false eastings and false northings
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State Plane Coordinate Zones
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State Plane Coordinate Zones
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City of Pittsburgh as Geographic Coordinates
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City of Pittsburgh as State Plane Coordinates
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State Plane Coordinate Names

• North American Datum of 1927 (NAD27)
• American Datum of 1983 (NAD83)
• "High Accuracy Reference Network" (HARN)
• "High Precision GPS Network" (HPGN)

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Universal Transverse Mercator System (UTM)

• Developed by the NATO in 1947
• Military grid system
• Based on transverse Mercator projection
• Applied to maps of the Earth's surface extending
  from the Equator to 84 Degrees north and 80
  degrees south latitudes

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UTM Zones
World is divided into 60 north-south zones, each
covering a strip 6 wide in longitude
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UTM Zones in the Contiguous USA
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Data Sources
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Other Sources of GIS Data

• US Census
• ESRI Web Sites and Media Kit
• Local Agencies
• Land Surveys
• Satellite Remote Sensing
• Existing Paper Maps
• Other WEB Sites

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US Census

• www.census.gov
• TIGER Maps
• Summary File(SF) Tables

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Census Tracts (TIGER)

• Small, relatively permanent statistical
  subdivisions of counties
• delineated by local committees in accordance with
  Census Bureau guidelines
• between 1,000 and 8,000 people (in general)
• 1,700 housing units or 4,000 people
• homogeneous population characteristics (economic
  status and living conditions)
• normally follow visible features
• may follow governmental unit boundaries and other
  non visible features
• more than 60,000 census tracts in Census 2000

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State Census Tracts
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County Census Tracts
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City Census Tracts
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Census Blocks Groups

• Block groups (BGs) are the next level below
  census tracts in the geo-graphic hierarchy
• - a subdivision of a census tract
• -400 housing units, with a minimum of 250, and a
  maximum of 550 housing units
• -follow clearly visible features, such as roads,
  rivers, and railroads.

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Census Block Groups
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Census Blocks

• Smallest geographic area for which the Census
  Bureau collects and tabulates decennial census
  information.
• Block boundaries are visible (street, road,
  stream, shoreline, etc.) or nonvisible (county
  line, city limit, property line, etc.) features.

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Census Blocks
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Other Census TIGER Layers
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Summary File (SF) Tables American Factfinder
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SF1 Tables
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SF2 Tables
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SF3 Tables
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ESRIs Website
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Data Sources
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ESRI Media Kit

• Data and Maps
• 8 CDs and DVDs
• Data Maps and StreetMap USA (DVD)
• Image Data (DVD)
• Global Imagery (DVD)
• World, Europe, Canada, and Mexico (CD)
• United States (CD)

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Local GIS Departments
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Local GIS Departments

• Chicago, IL
• http//egov.cityofchicago.org/
• Austin, TX
• http//www.ci.austin.tx.us/development/
• Tip Search by county name (Travis, County Texas)

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GIS Consulting Firms

• Specifies boundaries, rights-of-way, and other
  legal descriptions
• Surveyors use optical and electronic instruments
  to measure precise control point locations
  established by geodesists
• High quality data, but takes a lot of time

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Existing Paper Maps

• Vector Digitizing
• Raster Scanning

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GIS Servers
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Geography Network

• www.geographynetwork.com

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Geography Network
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Penn State (PASDA)

• http//www.pasda.psu.edu/

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Penn State (PASDA)
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Penn State (PASDA)
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Ivan Flood Maps
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Summary

• GIS Data Sets
• Map Projections
• Coordinate Systems
• GIS Data Sources