Datum Shift Methods
Valid datum shift method names are listed below.
AGD66
This transformation converts geographic coordinates based on the Australian Geodetic Datum of 1966 to geographic coordinates based on the Geocentric Datum of Australia (1994). The conversion to GDA94 is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Agd66ToGda94.gdc.
AGD84
This transformation converts geographic coordinates based on the Australian Geodetic Datum of 1984 to geographic coordinates based on the Geocentric Datum of Australia (1994). The conversion is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Agd84ToGda94.gdc.
ATS77
This method is similar to NAD83 but applies to the ATS77 (Atlantic Provinces of Canada). The conversion from ATS77 to CSRS is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Ats77ToCsrs.gdc.
Bursa Wolfe
This is a seven-parameter geocentric shift used by a few geocentric datums. Bursa Wolfe is considered to be more accurate than Molodensky because it allows for X, Y, Z rotation and scaling about the geocenter in addition to X, Y, Z displacement.
BW7
This is a seven-parameter geocentric shift used by a few geocentric datums. BW7 is considered to be more accurate than Molodensky because the mathematics used internally are more accurate than the more standard Bursa Wolfe method. BW7 is used less commonly than Bursa Wolfe in this product because most users need to match existing data standards.
CHENXY
This transformation converts geographic coordinates based on the CH1903 to geographic coordinates for Switzerland only. The conversion is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Ch1903ToPlus.gdc.
CSRS
This method is similar to NAD83 but applies to the NAD83/CSRS 1998 Canadian variation. The conversion from NAD27 and NAD83 are based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Nad27ToCsrs.gdc and Nad83ToCsrs.gdc.
DHDN
This transformation converts geographic coordinates based on the DHDN to geographic coordinates based on ETRF89 for Germany only. The conversion is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named DHDNToEtrf89.gdc.
ED50
This transformation converts geographic coordinates based on the European Datum of 1950 to geographic coordinates based on ETRF89 for Spain only. The conversion is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Ed50ToEtrf89.gdc.
ETRF89
The ETRF89, also occasionally named ETRS89, is the common datum applicable to Europe of which many local realizations can be found. This datum is reputed coincident with WGS84 upon Europe. No transformation is applied to convert to WGS84.
GDA94
This is a table-driven shift method used for Australia. The shift uses grid data files which are intended to be the same type of format as those developed for the Canadian National Transform V2. Grid data file locations must be added to the Grid data catalog in the search sequence desired.
GEOCENTRIC
This method is the newest 3-parameter transformation and supersedes the previous 3-parameter transform. The equations are slightly different and produce slightly different results, yet these results are very similar to the deprecated 3-parameter original version. The previous method is still provided in order to support previously produced data so conversion can result in consistent changes.
HPGN
Also known as HARN. This is a table-driven geocentric shift method considered to be more accurate than WGS84. Many U.S. states have coordinate systems using this standard. Grid data file locations must be added to the Grid data catalog in the search sequence desired.
Japanese Geodetic Datum of 2000
This transformation converts geographic coordinates based on the TOKYO datum to the Japanese Geodetic Datum of 2000 (JGD2K). This datum is another of the many renditions of WGS84. The conversion is based on grid shift file TKY2JGD.PAR provided with this product. If other files are to be used they must be listed in the Geodetic data catalog named TokyoToJgd2k.gdc.
Mulreg
This is a highly accurate shift method applied to a local area. All shift methods delivered are specific to a particular datum definition. Users cannot define their own Mulreg.
NAD27
This is a table-driven data shift method which relies on NADCON tables to be present for greatest accuracy. If the tables are not present, geocentric methods can (optionally) be applied. For Canadian mapping purposes, NOT or NTV2 is used with appropriate data files. Grid data file locations must be added to the Grid data catalog in the search sequence desired.
NAD83
This is a table-driven data shift method which relies on NADCON tables to be present for greatest accuracy. If the tables are not present, geocentric methods can (optionally) be applied. NAD83 is, for all intents and purposes, equivalent to WGS84. For Canadian mapping purposes, NT1 or NT2 is used with appropriate data files. Grid data file locations must be added to the Grid data catalog in the search sequence desired.
NZGD2K
This is a table-driven shift method used for New Zealand. The conversion from Nzgd1949 is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Nzgd49ToNzgd2K.gdc.
NZGD49
This transformation converts geographic coordinates based on the New Zealand Geodetic Datum of 1949 to geographic coordinates based on the New Zealand Geodetic Datum of 2000. The conversion is based on grid shift files which are in the Canadian National Transformation, Version 2 format. The files to be used must be listed in the Geodetic data catalog named Nzgd49ToNzgd2k.gdc.
RGF93 (NTF [Nouvelle Triangulation Française / New Transform for France])
This is a grid file shift that relies on values found in the data file gr3df97a.txt, which is distributed with the tables directory of this product. This method will also make use of grid shift files which are in the Canadian National Transformation, Version 2 format if they are specified in the Geodetic data catalog named Rgf93ToNtf.gdc.
TOKYO
This transformation converts geographic coordinates based on the Tokyo Datum to geographic coordinates based on the Japanese Geodetic Datum of 2000. Currently, a single file format is supported: a text format devised by an agency of the Japanese government. It appears that there is a single large file which covers the entire nation of Japan. Due to the file format, it is easy to produce smaller regional files. Thus, it may be that you will have several files to work with, and a Geodetic data catalog has been implemented for this purpose. The files to be used must be listed in the Geodetic data catalog named TokyoToJgd2k.gdc.