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Est. of Vertical Uncertainties | |
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VDatum 3.0, GEOID12A and GEOID96 released [October 23, 2012]!
VDatum is a free software tool being developed jointly by NOAA's National Geodetic Survey (NGS), Office of Coast Survey (OCS), and Center for Operational Oceanographic Products and Services (CO-OPS). VDatum is designed to vertically transform geospatial data among a variety of tidal, orthometric and ellipsoidal vertical datums - allowing users to convert their data from different horizontal/vertical references into a common system and enabling the fusion of diverse geospatial data in desired reference levels.
VDatum was first introduced to support a seamless bathymetric - topographic digital elevation model (DEM) for Florida's Tampa Bay region by merging the "best available" NOAA bathymetric data and USGS topography data. The best available bathymetric data were selected from the NOAA / NOS Hydrographic Survey database. For the Tampa bay region, approximately half of the sounding data collected were referenced to a mean low water (MLW) vertical datum, and the other half to a mean lower low water (MLLW) vertical datum. The best available topographic data were selected from the USGS National Elevation Dataset (NED). The NED dataset is horizontally referenced to NAD 83 and vertically referenced to NAVD 88. Prior to merging, both dataset were transformed to a common reference coordinate system, both horizontally and vertically, using VDatum.
The seamless bathy-topo DEM resulting from the VDatum Demonstration Project in Tampa Bay has not only proved to solve the problem of inconsistency among diverse dataset of bathymetry, topography and shorelines data that causes difficulty in mapping coastal regions, but also provides standard geospatial data for multiple applications. Applications benefiting from VDatum include: