Missoula County

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Missoula County

• Cadastral Control Digital Mapping
• Doug Burreson
• Mapping / GIS Supervisor
• Missoula County

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Digital Map History

• Program began in 1988
• CAD based
• Predated affordable 24k DLG
• Predated State adopted GCDB method
• Low budget
• Parcel data complete for Missoula County and in
  maintenance 1995

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Method adopted (early years)

• Calibrated to 24k 2 30 grid tics (no plss
  control)
• PLSS (and other features) digitized from 24k data
• Tried to use locally acquired ground control in
  urban area
• Reputable record survey data used when possible

4
Method adopted (later)

• Least squares (CMM) used to salvage local ground
  control.
• Adjusted basemap to local control in urban area
• Still no control in rural areas.

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GIS Needs Assessment Completed Recommends

• Establish Township control County-wide
• Establish Section Corner control for areas gt 120
  units / sq. mile (1 unit / 5 acres)
• Establish Quarter-Section control for areas gt 640
  units / sq. mile (1 unit / acre)
• Adjust existing map data to new control
• Hold all new Subd. COSs to the control
  network. Adjust existing parcel fabric to the
  newer surveys.

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Adjust existing map data to new control

• Waiting for completion of control work
• Waiting for a mature product to assist this
  process (ArcSurvey?)
• Goal Minimize the adjustment of good data while
  minimizing the wholesale remapping of large areas

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Upgrade Process (theoretical)

• Enhanced GCDB process
• 1. Use GPS control,
• 2. Reputable contemporary measurements,
• 3. Lastly GLO

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Township Control Status
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Township Urban Control
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Urban Control Status
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CustodianshipAn Integrated Approach

• All proposed surveys referenced to control
• Capture Save Survey Dept. review files
• Populate basemap with review data when survey is
  recorded
• Resolve anomalies
• Publish data

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Questions
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Address

• This presentation will be posted at
  http//www.co.missoula.mt.us/mapping_GIS/