Activities at the Louisiana Spatial Reference Center

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Activities at the Louisiana Spatial
ReferenceCenter
Louisiana State University
Roy K. Dokka, Ph.D. Center for GeoInformatics
and Louisiana Spatial Reference Center Louisiana
State University, Baton Rouge, LA 70803
2009 Height Modernization Meeting Beaumont, TX
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Gulf Coast A vulnerable landscape with a
constantly changing landscape
NOAA told the U.S. Congress in 2001 that the
system used to measure elevations in LA was,
inaccurate and obsolete and unable to support
public safety.
Bad vertical control affects levees, planning,
evacuation roads, FEMA flood maps, and LiDAR.
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A system of accurate elevations has been near
impossible to maintain in along the Gulf Coast.
Why?

• Subsidence.
• A lack of understanding of how and why
  subsidence occurs.
• A willingness to accept the best available
  data instead of accurate and sufficiently
  precise data to meet requirements and the
  standard of care.
• No Leadership or

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What is the overall strategyregarding 3-D
positioning in LA?

• The ability to obtain accurate elevations has
  always been a shared responsibility between NGS,
  local government, surveyors, and others.
• NGS is committed to providing users in LA with
  access to the NSRS. This means
• Maintaining a basic backbone of about a few
  hundred benchmarks in south Louisiana,
• Supporting CORS,
• Providing a geoid model,
• Development of technical standards.
• LSU will provide state-wide GNSS technology to
  facilitate accurate and precise anywhere-any
  time 3-D positioning.

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Bottomline?

• Local people and governments will have to decide
  how they wish to access the NSRS. You will have
  to pay for it and live with the consequences.
  Your choices are
• Maintain traditional vertical control.
• Real-time 3-D positioning.
• Hybrid of 1 and 2.
• Do nothing.

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LSUs Role in Fixing the Problem
Positioning Louisiana for the future

• Operation of GULFNet GPS Reference Network across
  South Louisiana
• CORS. Users can access the National Spatial
  Reference System anywhere in Louisiana with
  confidence. Think of CORS as smart benchmarks.
  GULFNet is updated daily and will remain accurate
  into the future without costly re-observations.
  Heights recognized as legal under Louisiana State
  law. www.ngs.noaa/CORS
• Creation of a State-wide Real-time Network
• GULFNet real-time kinematic GPS RTN network
  allows users to obtain accurate and precise 3-D
  positions anywhere-anytime in Louisiana.
  Precision 1 cm Horiz., 2 cm Vert. Users can
  obtain 2004.65 elevations by site calibration.
• Outreach
• Develop and provide know-how to enable users to
  exploit the new resources.

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Distance to a CORS
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Time on a Mark
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How does single base RTK work?
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Conventional Single Base RTK
Rover linked to base via radio

• Need a base a radio,
• and a rover.
• Added time for
• base set-up
• processing
• of base(s).
• Time intensive compared
• to RTN.
• Errors accumulate at
• 1ppm away from base.

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How does GULFNet RTN work?
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RTN Real-Time Network Based on VRS technology
Positioning anywhere, any time
Relative vertical 2 cm (3 min.)
Kinematic mode 0.3 ft (1 sec.)
Cellular device to connect user to Internet and
LSU GULFNet RTN
Native output in CORS 2002 but can easily be
put in 2004.65 context through calibration.
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HeightMatters!Especially in Louisiana
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The Louisiana Legislature requested LSU measure
the height of the South LA HPS in 2006-2007. N
50,000 points
Note Does not reflect post 2007 changes Due to
construction by USACE
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FEMA mapping partners need to use real weir
elevations in ADCIRC models
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Katrina SLOSH using accurate topography
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How about FEMA flood maps in Southeast Texas
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US 90
I-10 at US 90 FEMA (green) Gulfnet RTM
(black)
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Summary of Activities at LSRC
Positioning Louisiana for the future

• Operation of GULFNet GPS Reference Network across
  South Louisiana
• 50 CORS. Users can access the National Spatial
  Reference System anywhere in Louisiana with
  confidence. Think of CORS as smart benchmarks.
  GULFNet is updated daily and will remain accurate
  into the future without costly re-observations.
  Heights recognized as legal under Louisiana State
  law. www.ngs.noaa/CORS
• Creation of a State-wide Real-time Network
• GULFNet real-time kinematic GPS RTN network
  allows users to obtain accurate and precise 3-D
  positions anywhere-anytime in Louisiana.
  Precision 1 cm Horiz., 2 cm Vert. Users can
  obtain 2004.65 elevations by site calibration.
• Outreach
• Provide know-how to enable users to exploit the
  new resources.

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Thank You!