In this article:
- About coordinate systems and grid shift (TIFF, GTX, GSB) files
- Downloading and installing grid shift files
- Adding references to missing grid shift files
- Verified WKT and grid shift files
- More WKT and grid shift files
About Coordinate Systems and Grid Shift Files
Skyline applications can perform geographic datum transformations, to convert between different geographic coordinate systems. For example, when importing layers into a project, layers are reprojected to the project's global reference coordinate system to ensure that data is properly aligned. Although the source file retains its original coordinate system, it is placed on the terrain according to the reprojection parameters. Similarly, layers can also be reprojected before export for the purpose of compatibility with other data and applications.
This holds true for both horizontal and vertical coordinate systems. Hence, if your layers have vertical coordinate systems that include different vertical datums, i.e., reference coordinate surfaces used for vertical positions, a transformation is necessary to convert between the vertical data in the different coordinate systems. This is performed using vertical datum grid shift files in GTX and TIFF formats, which shift and transform between these datums, by offsetting the vertical input coordinates by the amount specified by the loaded grids.
Some vertical coordinate system transformations also require the use of GSB (Binary Grid Shift) files, e.g., when converting between the NAD27, ATS77, NAD83 (Original), and NAD83 (CSRS) geodetic reference systems.
Note: GSB files are also used independently of GTX and TIFF files to perform horizontal grid shifts.
Downloading and Installing Grid Shift Files
Sometimes the Well-Known Text (WKT) of one of the coordinate systems in your project references a particular grid shift file that was not bundled with your installation, or the reference itself is missing from the WKT. In this case, you can manually add the missing grid shift information.
- Download the required grid shift file. See below: Verified files and More files.
- Install as follows:
Note: Generally, when one of the coordinate systems in your project references a particular grid shift file that was not found on your computer, a notification will display and a TEZ with the missing file will be automatically downloaded. If no file is automatically downloaded, follow the steps below.
- For TerraExplorer - Copy the grid shift files into the proj subdirectory under TerraExplorer's application files directory: C:\Program Files\Skyline\TerraExplorer Pro\proj.
-
For PhotoMesh - Copy the grid shift files into the proj subdirectory under PhotoMesh's application files directory and into the one under the fuser directory:
- C:\Program Files\Skyline\PhotoMesh\proj
- C:\Program Files\Skyline\PhotoMesh\Fuser\proj
- If you do not have the necessary permissions to copy to the paths above, the grid shift files can also be copied to either of the following paths:
- %ProgramData%\Skyline\gdal_proj_data (e.g., C:\ProgramData\Skyline\gdal_proj_data).
- %AppData%\Skyline\gdal_proj_data (e.g., C:\Users\[user name]\AppData\Roaming\Skyline\gdal_proj_data).
- If the reference itself to the grid shift file is missing from your WKT, add the reference as described here.
Adding References to Missing Grid Shift Files
Add the references within the WKT as follows. See example below.
- Add the GTX or TIFF reference in the EXTENSION parameter under the VERT_DATUM object.
- Add the GSB reference in the EXTENSION parameter under the DATUM object.
Verified WKT and Grid Shift Files
The files below are commonly used WKT and grid shift files whose accuracy has been verified. Regional files are available as well as a "world" one with global extent. Note that grid shift files are only valid in the specific geographic domain for which they were generated.
Australia
- GDA94 + AHD height
- Description: GDA94 + AHD height (EPGS: 4283 + 5711, AUSGeoid09_V1.01 base)
- Grid shift files:
-
WKT:
COMPD_CS["GDA94 + AHD height",
GEOGCS["GDA94",
DATUM["Geocentric_Datum_of_Australia_1994",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6283"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AXIS["Latitude",NORTH],
AXIS["Longitude",EAST],
AUTHORITY["EPSG","4283"]],
VERT_CS["AHD height",
VERT_DATUM["Australian Height Datum (AUSGeoid09_V1.01)",2005,
EXTENSION["PROJ4_GRIDS","AUSGeoid09_V1.01.gtx"],
AUTHORITY["EPSG","5111"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5711"]]]
- GDA94 + AHD height
- Description: GDA94 + AHD height (EPGS: 4283 + 5711, AUSGeoid2020_20180201 base)
- Grid shift files:
- WKT
COMPD_CS["GDA2020 + AHD height",
GEOGCS["GDA2020",
DATUM["Geocentric_Datum_of_Australia_2020",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
AUTHORITY["EPSG","1168"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AXIS["Latitude",NORTH],
AXIS["Longitude",EAST],
AUTHORITY["EPSG","7844"]],
VERT_CS["AHD height",
VERT_DATUM["Australian Height Datum (AUSGeoid2020_20180201)",2005,
EXTENSION["PROJ4_GRIDS","AUSGeoid2020_20180201.gtx"],
AUTHORITY["EPSG","5111"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","57111"]]]
Belgium
-
Belge 1972 / Belgian Lambert 72 + Ostend height
- Description: Belge 1972 / Belgian Lambert 72 + Ostend height (EPSG: 31370 + 5710)
- Grid shift files:
- Source: https://www.ngi.be/website/hulpmiddelen-voor-transformatie-van-coordinaten
- WKT:
COMPD_CS["Belge 1972 / Belgian Lambert 72 + Ostend height",
PROJCS["Belge 1972 / Belgian Lambert 72",
GEOGCS["Belge 1972",
DATUM["Reseau_National_Belge_1972",
SPHEROID["International 1924",6378388,297,
AUTHORITY["EPSG","7022"]],
EXTENSION["PROJ4_GRIDS","bd72lb72_etrs89lb08.gsb"],
AUTHORITY["EPSG","6313"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4313"]],
PROJECTION["Lambert_Conformal_Conic_2SP"],
PARAMETER["standard_parallel_1",51.1666672333333],
PARAMETER["standard_parallel_2",49.8333339],
PARAMETER["latitude_of_origin",90],
PARAMETER["central_meridian",4.36748666666667],
PARAMETER["false_easting",150000.013],
PARAMETER["false_northing",5400088.438],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["X",EAST],
AXIS["Y",NORTH],
AUTHORITY["EPSG","31370"]],
VERT_CS["Ostend height",
VERT_DATUM["Ostend",2005,
EXTENSION["PROJ4_GRIDS","hBG18.gtx"],
AUTHORITY["EPSG","5110"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5710"]]]
Canada
- HT2_1997
- Description: Canadian Geodetic Vertical Datum of 2013 (EPSG: 6647).
- Grid shift: HT2_1997 (gtx)
- WKT:
VERT_CS["CGVD2013 height",
VERT_DATUM["Canadian Geodetic Vertical Datum of 2013",2005,
EXTENSION["PROJ4_GRIDS","HT2_1997.gtx"],
AUTHORITY["EPSG","1127"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","6647"]]]
Israel
- ITM + Israel Geoid Datum
- Description: Israel Geoid + Vertical Datum based on ILUM v1.2 (EPSG: 2039+5773)
- Grid shift: Israel Geoid Datum (gtx)
- WKT:
COMPD_CS["Israel / Israeli 7P 030314 + Israel Geoid Datum",
PROJCS["Israel / Israeli 7P 030314",
GEOGCS["Israel",
DATUM["Israel",
SPHEROID["GRS 1980",6378137,298.257222101],
TOWGS84[24.0024,17.1032,17.8444,-0.33009,-1.85269,1.66969,-5.4248]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",31.7343936111],
PARAMETER["central_meridian",35.2045169444],
PARAMETER["scale_factor",1.0000067],
PARAMETER["false_easting",219529.584],
PARAMETER["false_northing",626907.39],
UNIT["Meter",1],
AXIS["Easting",EAST],
AXIS["Northing",NORTH]],
VERT_CS["Israel Geoid Datum",
VERT_DATUM["Israel Geoid Datum",2005,
EXTENSION["PROJ4_GRIDS","Israel_Geoid_Datum.gtx"],
AUTHORITY["EPSG","5171"]],
UNIT["meter",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5773"]]]
Japan
- GSIGEO2011
- Description: Japanese Geodetic Datum 2011 (EPSG: 6695)
- Grid shift: GSIGEO2011 (gtx)
- WKT:
VERT_CS["JGD2011 (vertical) height",
VERT_DATUM["Japanese Geodetic Datum 2011 (vertical)",2005,
EXTENSION["PROJ4_GRIDS"," GSIGEO2011.gtx"],
AUTHORITY["EPSG","1131"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","6695"]]]
The Netherlands
-
Amersfoort / RD New + nap height
- Description: Netherlands - onshore, Dutch Wadden Islands, 12-mile offshore coastal zone (Compound CS EPSG: 7415)
- Grid shift files:
- Source: https://www.nsgi.nl/web/nsgi/geodetische-infrastructuur/coordinatentransformatie
- WKT:
COMPD_CS["Amersfoort / RD New (GSB) + nap height (GTX)",
PROJCS["Amersfoort / RD New",
GEOGCS["Amersfoort",
DATUM["Amersfoort",
SPHEROID["Bessel 1841",6377397.155,299.1528128,
AUTHORITY["EPSG","7004"]],
EXTENSION["PROJ4_GRIDS","rdtrans2018.gsb"],
AUTHORITY["EPSG","6289"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4289"]],
PROJECTION["Oblique_Stereographic"],
PARAMETER["latitude_of_origin",52.15616055555555],
PARAMETER["central_meridian",5.38763888888889],
PARAMETER["scale_factor",0.9999079],
PARAMETER["false_easting",155000],
PARAMETER["false_northing",463000],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["X",EAST],
AXIS["Y",NORTH],
AUTHORITY["EPSG","28992"]],
VERT_CS["NAP height",
VERT_DATUM["Normaal Amsterdams Peil",2005,
EXTENSION["PROJ4_GRIDS","naptrans2018.gtx"],
AUTHORITY["EPSG","5109"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5709"]]]
UK
-
OSGB 1936 / British National Grid
- Description: OSGB 1936 / British National Grid + odn height (EPSG: 27700 + 5701)
- Grid shift:
- Source: https://www.ordnancesurvey.co.uk/gps/transformation
- WKT:
COMPD_CS["OSGB 1936 / British National Grid (GSB) + odn height (GTX)",
PROJCS["OSGB 1936 / British National Grid",
GEOGCS["OSGB 1936",
DATUM["OSGB_1936",
SPHEROID["Airy 1830",6377563.396,299.3249646,
AUTHORITY["EPSG","7001"]],
EXTENSION["PROJ4_GRIDS","OSTN15_NTv2_OSGBtoETRS.gsb"],
AUTHORITY["EPSG","6277"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4277"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",49],
PARAMETER["central_meridian",-2],
PARAMETER["scale_factor",0.9996012717],
PARAMETER["false_easting",400000],
PARAMETER["false_northing",-100000],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["EPSG","27700"]],
VERT_CS["ODN height",
VERT_DATUM["Ordnance Datum Newlyn",2005,
EXTENSION["PROJ4_GRIDS","OSGM15.gtx"],
AUTHORITY["EPSG","5101"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5701"]]]
-
Malin Head height
- Description: Malin Head Height Vertical Datum (EPSG: 5731)
- Grid shift: OSGM15_Malin (gtx)
-
WKT:
VERT_CS["Malin Head height",
VERT_DATUM["Malin Head",2005,
EXTENSION["PROJ4_GRIDS"," OSGM15_Malin.gtx"],
AUTHORITY["EPSG","5130"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5731"]]]
-
OSGM15_Belfast
- Description: Belfast Height Vertical Datum (EPSG: 5732)
- Grid shift: OSGM15_Belfast (gtx)
-
WKT:
VERT_CS["Belfast height",
VERT_DATUM["Belfast Lough",2005,
EXTENSION["PROJ4_GRIDS"," OSGM15_Belfast.gtx"],
AUTHORITY["EPSG","5131"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5732"]]]
USA
-
NAD83(HARN)
- Description: Full support is available for US State Plane Coordinate Systems in NAD83 (HARN) High Accuracy Reference Network (or HPGN, High Precision Geodetic Network). Note that the transformation packages are state-specific. Browse here for more information.
- Grid shift: NAD83(HARN) (gsb)
-
NAVD88 height
- Description: North American Vertical Datum 1988 (EPSG: 5703).
-
Grid shift: NAVD88 (gtx)
Note: This GTX should be used with the latest realization of NAD83 (HARN) from 2018 (relying on this and this) - WKT:
VERT_CS["NAVD88 height",
VERT_DATUM["North American Vertical Datum 1988",2005,
EXTENSION["PROJ4_GRIDS","g2018_conus.gtx,g2012a_alaska.gtx,g2012a_guam.gtx,g2012a_hawaii.gtx,g2012a_puertorico.gtx,g2012a_samoa.gtx"],
AUTHORITY["EPSG","5103"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","5703"]]]
- HT2_2010v70
- Description: Canadian Geodetic Vertical Datum of 2013 (EPSG: 6647).
- Grid shift: HT2_2010v70 (gtx)
- WKT:
VERT_CS["CGVD2013 height",
VERT_DATUM["Canadian Geodetic Vertical Datum of 2013",2005,
EXTENSION["PROJ4_GRIDS"," HT2_2010v70.gtx"],
AUTHORITY["EPSG","1127"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","6647"]]]
World
- EGM08_1 (EPSG: 3855)
- Description: Earth Gravitational Model at 1-minute spacing.
- Grid shift: egm08_1 (gtx)
- WKT:
VERT_CS["EGM2008 geoid height",
VERT_DATUM["EGM2008 geoid",2005,
EXTENSION["PROJ4_GRIDS","egm08_1.gtx"],
AUTHORITY["EPSG","1027"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","3855"]]]
- EGM08_2.5 (EPSG: 38551)
- Description: Earth Gravitational Model at 2.5-minute spacing.
- Grid shift: egm08_25 (gtx)
- WKT:
VERT_CS["EGM2008 geoid height",
VERT_DATUM["EGM2008 geoid",2005,
EXTENSION["PROJ4_GRIDS","egm08_25.gtx"],
AUTHORITY["EPSG","1027"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Up",UP],
AUTHORITY["EPSG","38551"]]]
More WKT and Grid Shift Files
If you don't find the files you need listed above, see the links below:
- For TerraExplorer 7.3 and higher - Click here to download a self-installing TerraExplorer TEZ file (for TerraExplorer users).
- For PhotoMesh and TerraExplorer lower than 7.3 - Click here to download the corresponding ZIP, that includes most common grid shift files.