THE NORTH AMERICAN DATUM OF 1983

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THE NORTH AMERICAN DATUM OF 1983 (NAD 83) And
the Municipality of Anchorage GIS Alaska
Surveying and Mapping Conference February 23,
2005 Charlie Barnwell GIS Manager Municipality
of Anchorage
barnwellce_at_muni.org, [phone]
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Status

• Alaska, often considered a frontier in
  development and innovation is now becoming the
  last frontier of using archaic mapping methods.
• The Municipality is one of the oldest ArcInfo GIS
  users in the state with lots of accumulated
  mapping and data from various sources.

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Then Now
File cabinets/paper--mylar
Electronic---Web access and kiosks
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Why do it?

• A good point to clean and check the morass of
  data weve built
• It makes sense to turn this into a community
  effort of
• sharing ideas,
• methods, code, and
• a lot of peer pressure.

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Municipality of Anchorage area
2,000 square miles, mostly wilderness400 square
miles is urbanized.
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Big Reasons

• Use of LIDAR and Satellite Imagery
• Vertical and horizontal control go hand in hand
• Technology Upgrade
• SDE, geodatabase, etc.
• Cadastral Project
• Expand the Bowl 2000 survey control network using
  RTK GPSand expand the GIS-based control point
  network
• Build a network of photo identifiable control
  points using RTK GPS
• Platform for a method for building a control base
  for GIS

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MOA geographic database
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Foundation Layers Imagery (3D view of satellite
imagery drape on LIDAR data)
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Foundation Layers LIDAR
Airborne laserscanning to survey the Earths
surface. Producing a long lasting accurate base
for GIS data. Part of Cadastral project to build
vertical and horizontal control.
already scanned area
area still to scan
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Two big questions

• Whats the harm in mixing DATUMS
• The question of legacy data. Does changing these
  back to NAD83 using NADCON make sense and what is
  lost along the way?

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The accuracy question

• Surveying scale vs. engineering vs. planning
  scale
• 3 cm. to 1 ft. 1 ft. to 2 ft.
  5 ft. to 10 ft.
• Absolute accuracy
• National map accuracy standards
• ASPRS accuracy
• Relative accuracy

Relative Accuracy Requirements
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Business Impacts

• E911 and other Fire and police mapping
• Data collection in various departments
• Transit
• Public works
• Planning
• E911
• Utilities