New York State Digital Ortho QAQC

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New York State Digital Ortho QA/QC

• High-res ortho program is in 6th year
• Produce new orthos for portion of the state
  (1/3) every year
• Now in 2nd 5-year contract. Current contract is
  for all-digital collection no film
• Produced portions of program in years 4 5 with
  digital sensors (Leica ADS40 and Z/I DMC).
  Contractor is now using DMC.
• All QA/QC performed in-house

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NYSDOP QA/QC

• Starts with ortho coverage layout
• Continues into ground control planning flight
  planning
• Review survey adjustments,
• aerotriangulation adjustments,
• terrain data (suitability)
• All orthoimagery is reviewed we do not do
  checks on samples
• An ortho tile is more than just the picture
• Uncompressed and compressed versions
• Geo-referencing files also need to be reviewed
• Almost always find something new each year
• QA/QC of Coincident orthos (Color CIR) 1.8X
  single set
• Problems in one set are not necessarily in the
  other

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Sample Checklist from 5 County AT Block

• West Zone AT Review
• HL Scale of photography mean 129150 max 31530  
  OKHL GSD mean 1.34 ft max 1.44 ft   OKLL Scale
  of photography mean 114780 max 15540   OKLL
  GSD mean 0.68 ft max 0.71 ft   OKGPS   OKAT
  control residuals   OKAmount of control  
  OK4ray analysis   OKPhoto coverage   OKFiles
  submitted   OK

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Aerotriangulation Review

• Elevation above terrain will result in the
  largest scanned pixel resolution of 0.86 ft

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NSSDA Standards

• http//www.fgdc.gov/standards/documents/standards/
  accuracy/chapter3.pdf

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Point to Point

• High Level flying height derived orthoimagery
  requires a NSSDA 95 confidence of 8 feet or
  better
• Low Level flying height derived orthoimagery
  requires a NSSDA 95 confidence of 4 feet or
  better

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Point to Point

• Design file over Ortho Image

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Accuracy report from DOT
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Imagery Point Statistics
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Imagery Review Bridges
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Following from ADS40(in Nassau County 2004)
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Artifacts in DMC images(NYC 2006)
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QA Screenshots
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QA replacement caused radiometry issue on tile
edges
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Hall of Fame
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