Distance measure

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Distance measure

• Point A
• UTM Eastings 450,000m Northings 4,500,000m
• Point B
• UTM Eastings 550,000m Northings 4,500,000m

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State Plane Coordinate System
Each state has one or more zones Zones are
either N-S or E-W oriented (except
Alaska) Each zone has separate coordinate
system and appropriate projection Unit
feet no negative numbers
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Map Projections for State Plane Coordinate System
E-W zones
N-S zones
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(No Transcript)
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SPCS

• The origin for each zone is placed outside the
  zone to the southwest (a false origin)
• X-origin
• Transverse Mercator (N-S) Zones ? 500,000 feet
  west of the furthest point west
• Lambert Conformal Conic (E-W) Zones ? 2,000,000
  feet west of the furthest point west
• Y-origin is not a specific distance to the south
  (varies by state and zone)

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Use of SPCS
Advantages The system is used primarily for
engineering applications e.g. utility
companies, local governments to do accurate
surveying of facilities network (sewers, power
lines) More accurate than UTM. SPCS deals
with smaller area
Disadvantages Lack of universality cause
problems for mapping over large areas such as
across zones and states
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Data source

• Very few GIS projects have to start with no data
  at all.
• Data collected and made available by the various
  branches of government and third party vendors
• Finding existing map data?

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Data source in Davis Library
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Data source in Davis Library
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North Carolina

• Center for Geographic Information and Analysis

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Florida

• Florida Geographic Data Library (FGDL)

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Government data providers

• U.S. Geological Survey
• Imagery, DEMs, DRGs, DLGs
• U.S. Census Bureau
• TIGER
• National Oceanic Atmospheric Agency
• Coastal management
• Oil chemical spills
• Coral reef conservation
• Natural Resource Conservation Service
• STATSGO (U.S. General Soil Map)

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Data from USGS

• Digital line graphs (DLGs)
• Digital elevation model (DEMs)
• Land use and land cover digital data
• Digital cartographic text
• Digital orthophotoquads (DOQ)
• Digital raster graphics (DRG)

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U.S. Geological Survey

• Satellite image
• http//edcimswww.cr.usgs.gov/pub/imswelcome/

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US Census Bureau

• TIGER/Line Files
• TIGERTopologically Integrated Geographic
  Encoding and Referencing
• US Census Bureaus TIGER system automates the
  mapping and related
• geographic activities required to support the
  decennial census and sample
• survey program of the US census Bureau with the
  1990 decennial census.
• First comprehensive GIS database at street level
  for the
• entire United States

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Data Content of the TIGER/Line Files
Three major types Line features roads,
railroads, hydrography, and boundaries
Landmark features (1) Point landmark
schools, churches etc. (2) area
landmark parks, cemeteries etc. Polygon
features geographic entities Note line and
polygon features are the majority of
data Topology provides the foundation for
organizing spatial objects in the census
TIGER data base.
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Third Party Vendors

• ESRI
• TeleAtlas Map Databases
• DeLorme Street Atlas Topo Usa
• GeoCommunity Data Bundles

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Creating New Data

• Digitizing
• Scanning
• Field and Image data

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• Digitizing
• Transforms information from analog format (e.g.,
  paper, Mylar) ? digital format for computer
  storage display
• Vector data capture
• Methods
• Digitizing tablet
• On screen digitizing using PC

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Digitizing Tablet

• Electronically active table surface
• Fine grid of wires acts as a Cartesian coordinate
  system
• Small large formats available

http//www.calmit.unl.edu/geog412/Digitizing.pdf
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Digitizing Tablet

• Puck
• Connected to tablet
• Records locations from map
• Crosshair ? feature locator
• Buttons ? indicate beginning/ending of
  lines/polygons, left/right polygons

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On-screen digitizing w/ PC

• Also called heads-up digitizing

http//www.esri.com/news/arcnews/winter0102article
s/epas-clean-water.html
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Input devices Scanners

• Types
• Desktop scanner
• Drum scanners
• Drum scanner receives an entire sheet map,
  usually clamped to a rotating drum, and scans the
  map with very fine increments of distance.

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Raster Data Input Remote Sensing

• Aerial photography
• Source of base map data for many products ? check
  products 1st
• Distortions caused by scale, relief, tilt
• Orthophotos/orthophotoquads
• Type of aerial photo
• Corrected for scale, relief, tilt distortion
• Available in analog digital formats
• Satellite Imagery
• Requires geometric radiometric processing
• Geometric processing GCPs
• Classification accuracy assessment

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GPS Data Input

• Supports development of highly accurate geodetic
  control
• Links field data collection to locations
• Cost accuracy vary