Welcome to VDatum!

VDatum is a free software tool 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.

Converts the following:

• Horizontal datums: from NAD 27 or NAD 83(1986) to NAD 83(HARN). NAD83(HARN) is currently considered as being equivalent to NAD 83(NSRS2007/CORS96), WGS 84 or ITRF
• Vertical datums: among three vertical groups: tidal datums, orthometric datums and ellipsoidal datums (i.e. three-dimension or 3-D datums), in which:
  
  • Transforms among ellipsoidal and orthometric datums are available throughout the United States;
  • The HTDP v2.9 is partially utilized to support conversions among ellipsoidal datums;
  • Current GEOID models such as GEOID 99, GEOID 03 and GEOID 06 are used to support direct conversions between the NAD 83 ellipsoidal datum and the NAVD 88 orthometric datum;
  • The VERTCON model is employed to support conversions between the NGVD 29 datum and the NAVD 88 datum;
  • The IGLD 85 model is employed to support conversions between IGLD 85 datum and the NAVD 88 datum;
  • Tidal datums are available in 27 areas.
• Input elevation data in geographic (Latitude, Longitude) and UTM coordinates.

A Little History

VDatum was firstly introduced to produce 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 were collected in reference to a mean low water (MLW) vertical datum, and the other half were collected for surveys using a mean lower low water (MLLW) vertical datum. The best available topographic data were selected from the USGS National Elevation Dataset (NED). 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 bathy-topo DEM has proved not only to solve the problem of inconsistency between diverse dataset of bathymetry, topography and shorelines data that has caused difficulty for mapping coastal regions, but also provides standard geospatial data for multiple applications. Applications benefiting from VDatum include:

• Inundation modeling: storm surge, tsunami, sea level impacts
• Ecosystem modeling and coastal managements
• Hydrographic survey depths using Kinematic GPS for vertical referencing
• Shoreline extracting from LiDAR data