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 -

The Geoprocessing tool embeds the Web-based Transformation Tool released by Lands Department of HKSAR in ArcGIS and provides an instant extraction of height information of Hong Kong Principal Datum from various coordinate systems/datums. The Transformation Tool from Lands Department uses the conversion methods, parameters and formulas listed in the "Explanatory Notes on Geodetic Datums in Hong Kong" (PDF) and the "Datum Transformation and Transformation Parameters" (The "7-parameters") (PDF) as well as the Geoid Model established by the Hong Kong Polytechnic University. Please refer to this guidelines for using this geoprocessing tool in ArcGIS Pro.(Note: This tool is only applicable in ArcGIS Pro, and for coordinates within Hong Kong territories.)

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.This particular layer allows you to convert from NAVD 88 to MHHW.Units: metersThese data are a derived product of the NOAA VDatum tool and they extend the tool's Mean Higher High Water (MHHW) tidal datum conversion inland beyond its original extent.VDatum was 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 (https://vdatum.noaa.gov/). However, VDatum's conversion extent does not completely cover tidally-influenced areas along the coast. For more information on why VDatum does not provide tidal datums inland, see https://vdatum.noaa.gov/docs/faqs.html.Because of the extent limitation and since most inundation mapping activities use a tidal datum as the reference zero (i.e., 1 meter of sea level rise on top of Mean Higher High Water), the NOAA Office for Coastal Management created this dataset for the purpose of extending the MHHW tidal datum beyond the areas covered by VDatum. The data do not replace VDatum, nor do they supersede the valid datum transformations VDatum provides. However, the data are based on VDatum's underlying transformation data and do provide an approximation of MHHW where VDatum does not provide one. In addition, the data are in a GIS-friendly format and represent MHHW in NAVD88, which is the vertical datum by which most topographic data are referenced.Data are in the UTM NAD83 projection. Horizontal resolution varies by VDatum region, but is either 50m or 100m. Data are vertically referenced to NAVD88 meters.More information about the NOAA VDatum transformation and associated tools can be found here.

VDatum is designed to vertically transform geospatial data among a variety of tidal, orthometric and ellipsoidal vertical datums -

Vertical datum transformation grids for Mexico and Mexico's Digital Surface Model referenced to the EGM96 vertical datum.1) Transformation surface between NGVD29 and NAVD 88: MexicoTransGridmmNGVD29toNAVD88.zip2) Transformation surface between NGVD29 and EGM96: MexicoTransGridmmNGVD29toEGM96.zip3) Mexico's Digital Terrain Model originally developed by INEGI referenced to EGM96 (the original CEM was referenced to NGVD29). These files were compressed using Zstandard.

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico. These integrated bathymetric-topographic DEMs were developed for NOAA Coast Survey Development Laboratory (CSDL) through the American Recovery and Reinvestment Act (ARRA) of 2009 to evaluate the utility of the Vertical Datum Transformation tool (VDatum), developed jointly by NOAA's Office of Coast Survey (OCS), National Geodetic Survey (NGS), and Center for Operational Oceanographic Products and Services (CO-OPS). Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. Coastal Services Center (CSC), the U.S. Office of Coast Survey (OCS), the U.S. Army Corps of Engineers (USACE), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of North American Vertical Datum of 1988 (NAVD 88) or Mean High Water (MHW) and horizontal datum of North American Datum of 1983 (NAD 83). Cell size ranges from 1/3 arc-second (~10 meters) to 1 arc-second (~30 meters). The NOAA VDatum DEM Project was funded by the American Recovery and Reinvestment Act (ARRA) of 2009 (http://www.recovery.gov/).

The Geocentric Datum of Australia 1994 (GDA94) is a static coordinate datum realised with respect to the International Terrestrial Reference Frame (ITRF) at the reference epoch of 1 January 1994. At this time GDA94 and ITRF were coincident, however, as a consequence of the tectonic motion of the Australian Plate, ongoing refinement of the ITRF and crustal deformation, the two reference frames have diverged and the absolute difference between them is now approximately 1 m. Consequently, precise coordinate transformations between ITRF and GDA94 are required for many applications, and in this study we review, improve and extend these transformations. We have computed new transformation parameters between ITRF and GDA94, including the specific ITRF realisations of ITRF1996, ITRF1997, ITRF2000, ITRF2005 and ITRF2008. The two most recent ITRF realisations, ITRF2005 and ITRF2008, after transformation have a root-mean-square difference of less than 10 and 30 mm in the horizontal and vertical components, respectively, with respect to GDA94 at the Australian Fiducial Network (AFN) stations. However, the magnitude of some residuals exceed 15 and 60 mm in the horizontal and vertical components, respectively, which reflects the accuracy limit of GDA94. We discuss implications and future strategies for managing the differences between GDA94 and ITRF, including novel coordinate transformation approaches and justifications for the modernisation of GDA.

Data consists of conversion factors that can be used to convert between numerous vertical tidal datums and the North American Vertical Datum of 1988 (NAVD88). The data cover the Eastern Shore of Virginia and parts of southeastern Maryland along with the surrounding coastal waters and are represented as approximately 100m (100.584m) resolution grids. The six included tidal datums are local mean sea level (LMSL), mean tidal level (MTL), mean low water (MLW), mean lower low water (MLLW), mean high water (MHW), and mean higher high water (MHHW). All vertical units are in meters. By combining multiple conversions to and from NAVD88, conversion between the various tidal datums is possible. Two versions of the conversion factor grids are provided for each NAVD88-to-tidal-datum pairing: one that only contains data for areas not masked as nodata by the NOAA VDatum program (original source data) and one that contains both the original and interpolated data (see below for details). Naming conventions used were "cfactor_DDD" for the original VDatum-detrived dataset where "DDD" is the local tidal datum and "cf_nd_DDD" for the dataset that includes interpolated values within the nodata masks (IDW interpolation across masked areas, typically upland regions but also shallow seaside bays and creeks for which no adequate tidal benchmarks were available). By definition, the baseline elevation (sea level or 0.0m elevation) for NAVD88 is referenced to the fixed International Great Lakes Datum of 1985 local mean sea level height value, at Rimouski, Quebec, Canada. Additional tidal bench mark elevations were not used to calculate NAVD88 due to the demonstrated variations in sea surface topography, i.e., the fact that mean sea level is not the same equipotential surface at all tidal benchmarks. The magnitude of the difference between local mean sea level (LMSL) at the tidal benchmarks of the Eastern Shore of Virginia and the NAVD88 defined sea-level varies from 0.039 to 0.149 meters BELOW zero NAVD88. Tidal prisms also vary at each tidal benchmark (in part due to differences in basin configuration and tidal interactions) causing the conversion factors for the other tidal datums to also vary spatially in similar but not identical patterns. The VDatum 3.2 software program from NOAA (http://vdatum.noaa.gov/) was used to convert the x,y,z center points of the 100m gridded data wherein all Z elevations were set equal to zero (0) from NAVD88 to each of the six local tidal datums (the X,Y horizontal WGS84 UTM 18N coordinates remained unchanged). The resulting conversion factors represent the new elevation at which the NAVD88 zero level would lie in reference to the new datum; thus, to convert from NAVD88 and the new tidal datum, one would add this conversion factor to the NAVD88 elevations to get elevations relative to the chosen tidal datum. To convert to NAVD88 from a given tidal datum, one would subtract the conversion factor from the tidal elevation. Data were turned back into gridded data with the same resolution and horizontal extent as the original data grid. The internal data grids used by the VDatum program mask as nodata most land areas (including marshes) plus many of the seaside shallow bays, either in part or in full, for which reliable tidal benchmark data is/was not available. As a result, the program cannot be used in these nodata areas, even if immediately adjacent to data areas. So as to make conversion factors available for these coastal bays and marshes and seaside watersheds of interest to the VCRLTER, conversion factors for gridded regions within the NOAA nodata masks were interpolated from neighboring data values using the inverse distance weighting (IDW) techniques employed by ESRI's ArcGIS 10.1 software. IDW interpolation resulted in conversion factors that varied gradually spatially when adjacent to the NOAA VDatum data grids but that often showed relatively sharp transitions when equidistant between different far-apart basins (such as mid-peninsula between the Chesapeake Bay and Atlantic Ocean, or within South Bay bounded by data constructed from tidal datums for the Atlantic Ocean (east), Ship Shoal Inlet (south), Sand Shoal Inlet (north), and Magothy Channel (west)). It is suggested that the appropriate use of this data is to convert elevation datasets referenced to a tidal datum to NAVD88 if integrating multiple datasets together over large areas, such as across the full Eastern Shore or across multiple watersheds or coastal bays, so as to not introduce artificial IDW-related transitions into otherwise vertically-consistent upland elevations or basin-scale bathymetric surveys. When converting elevations of fringing upland marshes, the conversion factors (including interpolated values) can likely be used directly on a cell-by-cell level to adjust the tidal elevations to NAVD88 or to another tidal datum without the involvement of any IDW-related transitions. Likewise for many of the back-barrier seaside marshes and bays of Accomack County in the northern portion of the data coverage where no channel tidal datums intervene between the Atlantic coastline and the Chesapeake Bay. However, when converting bathymetric survey data for individual bays or basins with significant nodata-masked areas that exhibit sharp IDW-related transitions, it is suggested that it would be more appropriate to use a single area-averaged conversion factor calculated across the whole basin (or across the whole basin minus any portion where the conversion factor is closer [more-related] to a channel on the other side of an upland barrier without connecting flow paths). Likewise when converting to tidal datums full upland mainland watersheds. This again should prevent introducing sharp transitions and steps into the bathymetry survey data, which it is assumed is otherwise internally consistent.

This Application Programming Interface (API) provides instant conversion between HK 1980 Grid Coordinates (Northing and Easting) and WGS84 (ITRF96) Geodetic Coordinates (Latitude and Longitude). The conversion methods, parameters and formulas used in the coordinate coversion tool provided in this API are maintained by the Survey and Mapping Office, Lands Department. It is only applicable for coordinates within Hong Kong. Users SHOULD NOT use the results for applications requiring precise point positions. Transformation between datums does not improve the accuracy. In most cases, the transformation coordinates would be less accurate, because of the errors in the transformation and projection computation would be added to the results. Please seek advice from professional land surveyors. For enquiry, please contact the Geodetic Survey Section, Survey and Mapping Office, Lands Department. For details, please refer to User Manual (English Only): http://www.geodetic.gov.hk/transform/tformAPI_manual.pdf

These data are a derived product of the NOAA VDatum tool and they extend the tool's Mean Higher High Water (MHHW) tidal datum conversion inland beyond its original extent. VDatum was 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 (http://vdatum.noaa.gov/). However, VDatum's conversion extent does not completely cover tidally-influenced areas along the coast. For more information on why VDatum does not provide tidal datums inland, see http://vdatum.noaa.gov/docs/faqs.html. Because of the extent limitation and since most inundation mapping activities use a tidal datum as the reference zero (i.e., 1 meter of sea level rise on top of Mean Higher High Water), the NOAA Office for Coastal Management created this dataset for the purpose of extending the MHHW tidal datum beyond the areas covered by VDatum. The data do not replace VDatum, nor do they supersede the valid datum transformations VDatum provides. However, the data are based on VDatum's underlying transformation data and do provide an approximation of MHHW where VDatum does not provide one. In addition, the data are in a GIS-friendly format and represent MHHW in NAVD88, which is the vertical datum by which most topographic data are referenced. Data are in the UTM NAD83 projection. Horizontal resolution varies by VDatum region, but is either 50m or 100m. Data are vertically referenced to NAVD88 meters.

The BLF55-NZGD2000 grid enables the conversion of normal-orthometric heights from the Bluff 1955 local vertical datum directly to New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights. BLF55-NZGD2000 is published on a one arc-minute grid (approximately 1.8 kilometres) extending over the benchmarks that nominally define the extent of the Bluff 1955 vertical datum (168.2° E to 168.9° E, 46.3° S to 46.8° S). The conversion value is represented by the attribute “delta”, in metres. This grid is a combination of New Zealand Quasigeoid 2016 NZGeoid2016 and the BLF55-NZVD2016 height conversion grid. Where NZGeoid2016 is the reference surface for the New Zealand Vertical Datum 2016 (NZVD2016), while the BLF55-NZVD2016 grid models the difference between the Bluff 1955 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. More information on converting heights between vertical datums can be found on the LINZ website.

The test data set can be used to test high accuracy coordinate transformation (for compiled GIS data) and coordinate conversion in and around Victoria in relation to the Geocentric Datum of Australia. The test data can be used to compare outputs from software that: · Claims to use the official Intergovernmental Committee on Survey and Mapping (ICSM) high accuracy combined 7 parameter/distortion model transformation process and incorporating or derived from file data contained in called National 66 (13.09.01).gsb (refer to (http://www.anzlic.org.au/icsm/gdatm/) which is provided in the National Transformation Version 2 (NTv2) grid file format. · Claims to perform conversions between coordinate types relating to the Australian Geodetic Datum and Geocentric Datum of Australia including: - Geographicals: Latitude and Longitude coordinates (ie AGD66 and GDA94), - Universal Transverse Mercator (UTM) grid coordinates (ie Australian Map Grid 1966 (AMG66) and Map Grid of Australia 1994 (MGA94)) and - Custom Lambert conformal conic projection coordinates relating to the Land Victoria Vicgrid66 and Vicgrid94 projection specifications as they apply to Victoria (refer to www.giconnections.vic.gov.au)

Feature Service for the National Geodetic Survey (NGS) GPS on Bench Marks for the Transformation Tool (GPSonBM TT) Campaign that is currently underway and will continue until early 2023. This campaign will provide users the ability to explore the priority list of bench marks and will be regularly updated to provide the best marks to help NGS develop the best transformation tool for converting heights from the current vertical datums to the North American-Pacific Geopotential Datum of 2022 (NAPGD2022) that is planned to be available at the end of 2022. This includes the following vertical datums: the North American Vertical Datum of 1988 (NAVD 88) for the Conterminous US and Alaska; the Puerto Rico Vertical Datum of 2002 (PRVD02) for Puerto Rico; the Virgin Islands Vertical Datum of 2009 (VIVD09) for the US Virgin Islands; the Guam Vertical Datum of 2004 (GUVD04) for Guam; and the Northern Marianas Vertical Datum of 2003 (NMVD03) for the Commonwealth of the Northern Mariana Islands. Note that the current American Samoa Vertical Datum of 2002 (ASVD02) is planned to be deprecated since it is no longer valid due to an earthquake. For more information about vertical datums visit the NGS Vertical Datums web page.This Feature Service provides most of the data for the NGS GPS on Bench Marks Transformation Tool Web MapThis Service is updated regularly to track progress of the GPSonBM TT Campaign.Data for this web map can be found here: NGS GPS on Bench Marks Web Site

This document provides a practical solution to the transformation of International Terrestrial Reference Frame (ITRF) coordinates into GDA94 coordinates. GDA94 is coordinate datum based on ITRF92 at the fixed epoch of 1994.0. ITRF coordinates will in general differ from GDA94 coordinates for two main reasons, namely tectonic motion of the Australian landmass and reference frame differences.

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico. These integrated bathymetric-topographic DEMs were developed for NOAA Coast Survey Development Laboratory (CSDL) through the American Recovery and Reinvestment Act (ARRA) of 2009 to evaluate the utility of the Vertical Datum Transformation tool (VDatum), developed jointly by NOAA's Office of Coast Survey (OCS), National Geodetic Survey (NGS), and Center for Operational Oceanographic Products and Services (CO-OPS). Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. Coastal Services Center (CSC), the U.S. Office of Coast Survey (OCS), the U.S. Army Corps of Engineers (USACE), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of North American Vertical Datum of 1988 (NAVD 88) or Mean High Water (MHW) and horizontal datum of North American Datum of 1983 (NAD 83). Grid spacings for both DEMs are 1/3 arc-second (~10 meters).

Warning: This raster is a grid of a floating-point values; not a surface. To derive an accurate height transformation value, this raster grid must be downloaded in terms of NZGD2000 and then converted into a surface using bilinear interpolation.

The Napier 1962 to NZVD2016 Conversion Raster provides users with a two arc-minute (approximately 3.6 kilometres) raster image of the conversion of normal-orthometric heights from the Napier 1962 local vertical datum to the New Zealand Vertical Datum 2016 (NZVD2016).

The conversion value is represented by the attribute “O”, in metres. This conversion and NZVD2016 are formally defined in the LINZ standard LINZS25009.

The height conversion grid models the difference between the Napier 1962 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. From the GPS-levelling marks the expected accuracy is better than 2 centimetres (95% Confidence interval).

More information on converting heights between vertical datums can be found on the LINZ website.

This dataset provides information about the position, position accuracy, mark name, mark type, condition and unique four letter code for geodetic marks in terms of New Zealand's official geodetic datum for the Ross Dependency.

This dataset only includes marks that are within Antarctica. These positions have been generated using geodetic observations such as precise differential GPS or electronic distance and theodolite angles measurements. The positions are either 2D or 3D depending of the availability of this measurement data.

The source data is from Land Information New Zealand's (LINZ) Landonline system where it is used by Land Surveyors. This dataset is updated daily to reflect changes made in the Landonline.

Accuracy

Geodetic marks with a coordinate order of 5 or less have been positioned in terms of Ross Sea Region Geodetic Datum 2000 (RSRGD2000) using precise differential GPS techniques. Marks with order 6 have been positioned in terms of RSRGD2000 using precise horizontal angles and distance measurements. Lower order marks (order 7 and greater) are derived from lower accuracy measurement techniques or historical datum transformations, and may be significantly less accurate.

The accuracy of RSRGD2000 coordinates is described by a series of 'orders' classifications. Positions in terms of RSRGD2000 are described by three-dimensional coordinates (latitude, longitude, ellipsoidal height). The accuracy of a survey mark is indicated by its order. Orders are classifications based on the quality of the coordinate in relation to the datum and in relation to other surrounding marks. For more information see http://www.linz.govt.nz/geodetic/datums-projections-heights/heights/coordinate-orders/

Note that the accuracy applies at the time the mark was last surveyed. Refer to the web geodetic database for historical information about mark coordinates.

Note also that the existence of a mark in this dataset does not imply that there is currently a physical mark in the ground - the dataset includes destroyed or lost historical marks. The geodetic database provides more information on the mark status, valid at last time it was visited by LINZ.

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico. These integrated bathymetric-topographic DEMs were developed for NOAA Coast Survey Development Laboratory (CSDL) through the American Recovery and Reinvestment Act (ARRA) of 2009 to evaluate the utility of the Vertical Datum Transformation tool (VDatum), developed jointly by NOAA's Office of Coast Survey (OCS), National Geodetic Survey (NGS), and Center for Operational Oceanographic Products and Services (CO-OPS). Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. Coastal Services Center (CSC), the U.S. Office of Coast Survey (OCS), the U.S. Army Corps of Engineers (USACE), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of North American Vertical Datum of 1988 (NAVD 88) or Mean High Water (MHW) and horizontal datum of North American Datum of 1983 (NAD 83). Grid spacings for both DEMs are 1/3 arc-second (~10 meters).

The GSB26-NZGD2000 grid enables the conversion of normal-orthometric heights from the Gisborne 1926 local vertical datum directly to New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights.

GSB26-NZGD2000 is published on a one arc-minute grid (approximately 1.8 kilometres) extending over the benchmarks that nominally define the extent of the Gisborne 1926 vertical datum (177.0° E to 178.6° E, 37.4° S to 39.0° S).

The conversion value is represented by the attribute “delta”, in metres.

This grid is a combination of New Zealand Quasigeoid 2016 NZGeoid2016 and the GSB26-NZVD2016 height conversion grid. Where NZGeoid2016 is the reference surface for the New Zealand Vertical Datum 2016 (NZVD2016), while the GSB26-NZVD2016 grid models the difference between the Gisborne 1926 vertical datum and NZVD2016 using the LINZ GPS-levelling marks.

More information on converting heights between vertical datums can be found on the LINZ website.

To map the predicted sea level rise for Barnstable County (Cape Cod) the most accurate elevation data was obtained and adjusted to account for vertical datum variations as well as localized tidal information. This adjusted data, was then separated into areas below sea level and into 1 ft increments (up to 6ft) above sea level. Topographical elevation data was sourced from remotely sensed LiDAR data which was collected in the Winter and Spring of 2011, while no snow was on the ground, rivers were at or below normal levels and within 90 minutes of the daily predicted low tide. For Barnstable County, the LiDAR was processed and classified to meet a bare earth Fundamental Vertical Accuracy (FVA) of 18.13 cm at a 95% confidence level. The topological elevation data was in a grid format, as a Digital Elevation Model (DEM) with a cell size of 1 meter. In order to incorporate tidal variability within an area when mapping sea level rise, a “modeled” surface (or raster) is needed that represents this variability. In addition, this surface must be represented in the same vertical datum as the elevation data. To account for the datum and tidal differences across the county the DEM was adjusted to localized conditions using the NOAA VDatum (Verticle Datum Transformation) software. The VDatum program was used to convert a 500m grid of points that covered the entire Barnstable County area from the source of North American Vertical Datum 88 (NAVD 88) to Mean Higher High Water (MHHW). MHHW is the average of the higher high water height of each tidal day observed over the National Tidal Datum Epoch. The 500m MHHW grid was then interpolated into a 1m grid that was identical in spatial extent to the 1m topographical DEM. The topographical DEM was then adjusted on a cell-by-cell basis to account for the MHHW elevation.