National Spatial
Reference System
OUTLINE
NATIONAL SPATIAL
REFERENCE SYSTEM
VERTICAL DATUMS
COMPARISON OF VERTICAL
DATUM ELEMENTS
NORTH AMERICAN VERTICAL
DATUM 88
NORTH AMERICA VERTICAL
HEIGHT SYSTEMS
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Heights Based on Geopotential
Number
The Geoid
Execution of Surveys;
Sources of Error
Geodetic Control
HEIGHT
SYSTEMS
GEOPOTENTIAL NUMBERS
HEIGHT
SYSTEMS
GEOPOTENTIAL NUMBERS
HEIGHT
SYSTEMS
GEOPOTENTIAL NUMBERS
HEIGHT
SYSTEMS
SEA LEVEL HEIGHTS
HEIGHT
SYSTEMS
DATUMS
HEIGHT
SYSTEMS
DATUMS
HEIGHT
SYSTEMS
DATUMS
HEIGHT
SYSTEMS
DATUMS
Slide 24
EXECUTION OF
SURVEYS
SOURCES OF ERROR
EXECUTION OF
SURVEYS
SOURCES OF ERROR
VERTICAL DATA REDUCTION
COMPUTATIONS
EXECUTION OF
SURVEYS
SOURCES OF ERROR
Error Sources Associated
With Differential Leveling
Error Sources Associated
With Differential Leveling
Error Sources Associated
With Differential Leveling
NAVD 88 DATUM DEFINITION
AND RESULTS
Slide 33
NAVD 88 PROGRAM
DEFINITION
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PRESENT NETWORK FOR NAVD
88
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NEW YORK VERTICAL NETWORK
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NORTH AMERICALN VERTICAL
DATUM
OF 1988 (NAVD 88)
NORTH AMERICAN VERTICAL
DATUM
OF 1988 (NAVD 88)
NORTH AMERICAN VERTICAL
DATUM
OF 1988 (NAVD 88)
NORTH AMERICAN VERTICAL
DATUM
OF 1988 (NAVD 88)
NAVD 88 DATUM DEFINITION
NAVD 88 GENERAL
ADJUSTMENT COMPLETION DATE OF JUNE 1991:
WHAT DOES THIS REALLY MEAN?
NAVD 88 GENERAL
ADJUSTMENT COMPLETION
DATE OF JUNE 1991:
WHAT DOES THIS REALLY MEAN?
Most surveying
applications should not be significantly affected because the changes in relative
height between adjacent bench marks should be less than 1 cm. As stated above, the absolute height values
will change much more, but this should not be a major concern to the
surveyor. The greatest problem the
surveyor will have is ensuring that all height values of bench marks in the
project area are referenced to the same
vertical datum, preferably NAVD 88 and labeled correctly (metadata). Other agencies’ bench marks, e.g., COE, FL
Department of Transportation, FL Department of Environmental Protection, and
USGS, were incorporated into NAVD 88 by NGS as these agencies provided, and
still do, their data in computer-readable form.
However, the leveling data associated with over 500,000 third-order
bench marks established by USGS have not been placed in computer-readable form
and do not have NAVD 88 heights. In
addition, COE has established hundreds of thousands of bench marks across the
nation which do not have NAVD 88 heights.
IMPACT OF NAVD 88
IMPACT OF NAVD 88
IMPACT OF NAVD 88
REASONS TO CONVERT
PRODUCTS TO NAVD 88
REASONS TO CONVERT
PRODUCTS TO NAVD 88
BENEFITS OF NAVD 88
BENEFITS OF NAVD
88
(CONTINUED)
Slide 59
NAVD 88 IMPLEMENTATION
NAVD 88 IMPLEMENTATION
FGCS VERTICAL WORK GROUP
ACSM AD HOC
COMMITTEE
GEOGRAPHIC MAKEUP
ACSM AD HOC
COMMITTEE
DISCIPLINE MAKEUP
FEMA’S RESPONSE
TO NAVD 88
FEMA’S Response to NAVD
88
FEMA’s Response to NAVD
88
FEMA’s Response to NAVD
88
FEMA’s Response to NAVD
88
FEMA’s Response to NAVD
88
FEMA’s Response to NAVD
88
FEMA’s Response to NAVD
88
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NGS’ RESPONSIBILITIES
NGS’ RESPONSIBILITIES
NGS’ RESPONSIBILITIES
NAVD 88 USER’S
RESPONSIBILITIES
NAVD 88 CONVERSION
TECHNIQUES
BASIC CONVERSION
TECHNIQUES
CONVERSION
TECHNIQUES
(CONTINUED)
CONVERSION TECHNIQUES
Slide 94
Review
Slide 96