[Federal Register Volume 72, Number 132 (Wednesday, July 11, 2007)]
[Notices]
[Page 37732]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 07-3377]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration


Notice To Adopt a Standard Model for Mathematical Vertical Datum 
Transformations

AGENCY: National Geodetic Survey (NGS), National Ocean Service (NOS), 
National Oceanic and Atmospheric Administration.

ACTION: Notice.

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SUMMARY: The purpose of this notice is to announce a decision by the 
Federal Geodetic Control Subcommittee (FGCS) to recommend adoption of a 
standard method for mathematical transformations between the vertical 
geodetic datums: The National Geodetic Vertical Datum of 1929 (NGVD 29) 
and the North American Vertical Datum of 1988 (NAVD 88). These methods 
are designated, in descending order of accuracy: (1) The recomputation 
or readjustment of survey observations method, (2) the mathematical 
transformation method, and (3) the average shift method. In order to 
maintain consistency of results and to minimize misuse associated with 
the mathematical transformation method, FGCS recommends software 
identified as VERTCON (Vertical Conversion) as a Federal standard.

DATES: Individuals or organizations wishing to submit comments on the 
adoption of VERTCON as the standard method, should do by August 10, 
2007.

ADDRESSES: Written comments should be sent to the attention of David 
Doyle, Chief Geodetic Surveyor, Office of the National Geodetic Survey, 
National Ocean Service (N/NGS2), 1315 East-West Highway, Silver Spring, 
Maryland 20910, fax 301-713-4324, or via e-mail [email protected].

FOR FURTHER INFORMATION CONTACT: Requests for additional information 
should be directed to David Doyle, Chief Geodetic Surveyor, National 
Geodetic Survey (N/NGS2), 1315 East-West Highway, Silver Spring, MD 
20910; Phone: (301) 713-3178.

SUPPLEMENTARY INFORMATION: The intent of this notice is to standardize 
a vertical datum transformation method when a mathematical 
transformation is desired. FGCS selected the method incorporated in the 
software identified as VERTCON. It is not the intent of the notice to 
declare when to use a datum transformation or by what method but only 
to declare that when a mathematical transformation is appropriate, 
VERTCON is recommended. Note that VERTCON is not appropriate to 
transform between NGVD 29 and NAVD 88 for first-, second-, or third-
order heights, as defined in the Federal Geodetic Control Committee 
(FGCC), Standards and Specifications for Geodetic Control Networks, and 
retain first- or second-, or third-order accuracies in the results. 
Method 1, recomputation or readjustment of survey observations, is 
usually more appropriate to maintain first-, second-, and third-order 
FGCC accuracies.
    VERTCON can be accessed for on-line computation from the NGS 
Geodetic Tool Kit at http://www.ngs.noaa.gov/TOOL/Vertcon/vertcon.html, 
or copies of the VERTCON software are available for free download from 
the NGS Web site http://www.ngs.noaa.gov/PC_PROD/pc_prod.shtml#VERTCON.

    Dated: July 5, 2007.
Elizabeth R. Scheffler,
Associate Assistant Administrator for Management, Ocean Services and 
Coastal Zone Management.
[FR Doc. 07-3377 Filed 7-10-07; 8:45 am]
BILLING CODE 3510-JE-M