GeodeticDatum.AlternativeDatumShifts Methods
Returns a collection of alternative datum shifts for this datum.
Overload List
| Name | Description | |
|---|---|---|
| Public method | AlternativeDatumShifts() | Returns a collection of datum shifts for this datum, excluding grid file datum shifts. (The datum shifts are represented by DatumShiftInfo instances.) |
| Public method | AlternativeDatumShifts(System.String gridFileRootPath) | Returns a collection of datum shifts for this datum, including grid file datum shifts. (The datum shifts are represented by DatumShiftInfo instances.) |
AlternativeDatumShifts()
Returns a collection of datum shifts for this datum, excluding grid file datum shifts. (The datum shifts are represented by DatumShiftInfo instances.)Syntax
public DatumShiftInfoCollection AlternativeDatumShifts ()Return Value
A collection of datum shifts from this datum to Wgs84. (They are represented by DatumShiftInfo instances.)
Remarks
The method assumes that the Authority and AuthorityCode of the geodetic datum are correct. These properties are read-only and cannot be set in the public GeodeticDatum constructor, but they will usually be set in the geodetic datum component of a Crs extracted from dataset files or constructed via Crs.FromAuthorityAndCode.
When you have chosen the DatumShiftInfo you want to use in the list of alternatives, you can get the corresponding datum shift via the DatumShift.FromInfo method.
Most of the returned datum shifts will come from the EPSG database, but some may come from other sources.
For some geodetic datums, Carmenta does not know any published datum shift at all; then this method will return an identity datum shift to Wgs84. Such a datum shift simply assumes that longitude/latitude in the geodetic datum are the same as in Wgs84, and can be wrong by up to about 1 km.
This method will not return any representation of a GridFileDatumShift. To get them too, you must use the overloaded variant that takes a gridFileRootPath parameter (the expected location of the grid files).
AlternativeDatumShifts(System.String gridFileRootPath)
Returns a collection of datum shifts for this datum, including grid file datum shifts. (The datum shifts are represented by DatumShiftInfo instances.)Syntax
public DatumShiftInfoCollection AlternativeDatumShifts (
System.String gridFileRootPath
)Parameters
The expected location of grid shift files (NTv2 or CTable format).
Return Value
A collection of datum shifts from this datum to Wgs84. (They are represented by DatumShiftInfo instances.)
Remarks
The method assumes that the Authority and AuthorityCode of the geodetic datum are correct. These properties are read-only and cannot be set in the public GeodeticDatum constructor, but they will usually be set in the geodetic datum component of a Crs extracted from dataset files or constructed via Crs.FromAuthorityAndCode.
When you have chosen the DatumShiftInfo you want to use in the list of alternatives, you can get the corresponding datum shift via the DatumShift.FromInfo method.
Most of the returned datum shifts will come from the EPSG database, but some may come from other sources.
For some geodetic datums, Carmenta does not know any published datum shift at all; then this method will return an identity datum shift to Wgs84. Such a datum shift simply assumes that longitude/latitude in the geodetic datum are the same as in Wgs84, and can be wrong by up to about 1 km.
This method can return a DatumShiftInfo that represents a GridFileDatumShift. The DatumShiftInfo.FileStatus will then tell whether the required grid file is found under the gridFileRootPath. If not, you must try to download it from the DatumShiftInfo.InformationSource before you construct the GridFileDatumShift.
Platforms
Windows, Linux, Android