DatumShiftInfo.Accuracy Property
Gets the accuracy of the datum shift (in the area of use).
Syntax
public System.Double Accuracy { get; }Property Value
Default: 999
The accuracy of the datum shift in meters.
Remarks
The accuracy can be found in the EPSG database or in other sources. It must be taken with a grain of salt, since the confidence level may be anything between 100 percent and 50 percent (seldom lower), depending on the original information source.
Note that a datum shift may be intended for an area of use that is smaller than the geodetic datum extent. It is risky to use a datum shift outside its area of use, since the accuracy cannot be predicted.
About accuracy, EPSG says:
"The coordinate operation accuracy information may be used for ranking transformations applicable to an area of interest. It needs to be treated with caution. Although described as accuracy, in reality the value may be a measure of the internal precision of the transformation derivation. Whilst accuracy for transformations from a single information source may be safely ranked, 'accuracy' from different information sources may not be consistent." (OGP Geomatics Guidance Note number 7, part 1, paragraph 6.5.4.1.)
The default value, 999 meters, means "don't know". The value is used in the EPSG database when an accuracy estimate is not available from the information source.
Another special value, 1111 meters, is used when Carmenta Engine knows nothing about a geodetic datum, and has constructed a datum shift by assuming that longitude/latitude in the datum are the same as longitude/latitude in Wgs84. Such an assumption can be wrong by about a kilometer.
Among the datum shifts for which EPSG does publish an accuracy estimate, nearly all have an accuracy of 50 meters or better; only three are worse (these three have an accuracy of 100 meters).
See also OriginalAccuracy.
Platforms
Windows, Linux, Android