ArcObjects Library Reference (Geometry)

ISpatialReference.GetFalseOriginAndUnits Method

Get the false origin and units.

[Visual Basic .NET]
Public Sub GetFalseOriginAndUnits ( _
    ByRef falseX As Double, _
    ByRef falseY As Double, _
    ByRef xyUnits As Double _
)

[C#]
public void GetFalseOriginAndUnits (
    ref double falseX,
    ref double falseY,
    ref double xyUnits
);

[C++]
HRESULT GetFalseOriginAndUnits(
  double* falseX,
  double* falseY,
  double* xyUnits
);

[C++]

Parameters
falseX [out]
  falseX is a parameter of type double
falseY [out]
  falseY is a parameter of type double
xyUnits [out]
  xyUnits is a parameter of type double

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Description

An alternative method to the GetDomain method. The falseX and falseY values correspond to the minimum X and minimum Y values of the XY domain. The xyUnits is the same as the precision or scale value. The inverse of the xyUnits defines the resolution of the data stored in the geodatabase. The resolution is used to snap data when it is stored in the geodatabase.

The falseX, falseY, and xyUnits use the same unit of measure as the coordinate system.

Sample values if data is based on a geographic coordinate system are:

falseX=-180
falseY=-90
xyUnits=1000000


Sample values if data is based on a projected coordinate system are:

falseX=200000

falseY=4000000

xyUnits=100

In the first example, the data is using a geographic coordinate system so the falseX and falseY values are in degrees. The inverse of the xyUnits is 0.000001 degrees.

In the second example, the data is using a projected coordinate system. Let us assume that the unit of measure is meters. The smallest coordinates values that a feature can have is x=200000 meters and Y=4000000 meters. The inverse of the xyUnits is 0.01 (meters) which means data will be snapped to the closest centimeter when it is stored.

Remarks

Use this function to retrieve the following information about the spatial reference of the geometry:

falseX: XMin of the domain.

falseY: YMin of the domain.

XYUnits: Precision of the domain.

[C#]

//This code example shows how to get the false origin and units of a dataset
private void GetFalseOriginAndUnits(IFeatureClass featureClass)
{
    IGeoDataset geoDataset=featureClass as IGeoDataset;
    //get access to SpatialReference through IGeoDataset
    ISpatialReference spatialReference=geoDataset.SpatialReference;
    //get the false origin and units of the dataset
    double falseX;
    double falseY;
    double xyUnits;
    spatialReference.GetFalseOriginAndUnits(out falseX, out falseY, out xyUnits);
    System.Windows.Forms.MessageBox.Show(falseX + ", " + falseY + ", " + xyUnits);
}

[Visual Basic .NET]

    'This code example shows how to get the false origin and units of a dataset.
    'This example assumes that a valid workspace object has already 'been established.
    Sub GetFalseOriginAndUnits_Example(ByVal pWorkspace As IWorkspace)
        Dim pFeatWS As IFeatureWorkspace
        pFeatWS=pWorkspace
        Dim pFeatDS As IFeatureDataset
        pFeatDS=pFeatWS.OpenFeatureDataset("railroad")
        Dim pGeoDataset As IGeoDataset
        pGeoDataset=pFeatDS

        'get access to SpatialReference through IGeoDataset
        Dim pSpatRef As ISpatialReference
        pSpatRef=pGeoDataset.SpatialReference

        'declare variables that will be used to store the
        'false origin and units of the dataset
        Dim dFalseX As Double
        Dim dFalseY As Double
        Dim dXYUnits As Double
        'get the false origin and units of the dataset
        pSpatRef.GetFalseOriginAndUnits(dFalseX, dFalseY, dXYUnits)
        Debug.Print(dFalseX & ", " & dFalseY & ", " & dXYUnits)
    End Sub

.NET Samples

Curve conversion add-in (Code Files: CurveConversionDockWin)

.NET Related Topics

Converting between high- and low-precision spatial references