ISpatialReference Interface

Provides access to members that control a SpatialReference. Note: the ISpatialReference interface has been superseded by ISpatialReference3. Please consider using the more recent version.

Product Availability

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

Description

The spatial reference is not defined when creating a new instance of a geometry. It is the developer's responsibility to define a spatial reference that makes sense for the geometry and for the operation. To achieve precise and predictable results using the geometry library, it is essential that the spatial reference of geometries within a workflow is well defined. When performing a spatial operation using two or more geometries, for example an intersection, the coordinate systems of the two geometries must be equal. If the coordinate systems of the geometries are different or undefined, the operation could produce unexpected results.

Members

		Description
	Abbreviation	The abbreviated name of this spatial reference component.
	Alias	The alias of this spatial reference component.
	Changed	Notify this object that some of its parts have changed (parameter values, z unit, etc.).
	FactoryCode	The factory code (WKID) of the spatial reference.
	GetDomain	The XY domain extent.
	GetFalseOriginAndUnits	Get the false origin and units.
	GetMDomain	The measure domain extent.
	GetMFalseOriginAndUnits	Get the measure false origin and units.
	GetZDomain	The Z domain extent.
	GetZFalseOriginAndUnits	Get the Z false origin and units.
	HasMPrecision	Returns true when m-value precision information has been defined.
	HasXYPrecision	Returns true when (x,y) precision information has been defined.
	HasZPrecision	Returns true when z-value precision information has been defined.
	IsPrecisionEqual	Returns TRUE when the precision information for the two spatial references is the same.
	Name	The name of this spatial reference component.
	Remarks	The comment string of this spatial reference component.
	SetDomain	The XY domain extent.
	SetFalseOriginAndUnits	Set the false origin and units.
	SetMDomain	The measure domain extent.
	SetMFalseOriginAndUnits	Set the measure false origin and units.
	SetZDomain	The Z domain extent.
	SetZFalseOriginAndUnits	Set the Z false origin and units.
	ZCoordinateUnit	The unit for the Z coordinate.

Inherited Interfaces

Interfaces	Description
ISpatialReferenceInfo	Provides access to members that control the properties common to all components of a spatial reference system.

CoClasses that implement ISpatialReference

CoClasses and Classes	Description
GeographicCoordinateSystem	Creates a geographic coordinate system.
ProjectedCoordinateSystem	Creates a projected coordinate system.
UnknownCoordinateSystem	Creates an unknown coordinate system.

[C#]

The following code demonstrates how to compare two spatial references. There are two ways shown in the example one using IClone and the other using ICompareSpatialReferences and the IsEqualNoVCS method

        public static bool CompareSpatialRefs(ISpatialReference sourceSR, ISpatialReference targetSR)
        {
            IClone sClone = sourceSR as IClone;
            IClone tClone = targetSR as IClone;

            // first level test compares the coordinate system component
            if (!sClone.IsEqual(tClone))
                return false;

            return true;
        }

[Visual Basic 6.0]

The following code example demonstrates how to compare two spatial references. It uses the ISpatialReference2 interface to compare the XY precision in addition to the coordinate system. This is the same type of comparison that is performed by the Copy/Paste functionality in ArcCatalog.

Public Function CompareSpatialReferences(ByVal pSourceSR As ISpatialReference, ByVal pTargetSR As ISpatialReference) As Boolean

Dim pSourceClone As IClone
Dim pTargetClone As IClone
Dim bSREqual As Boolean

Set pSourceClone = pSourceSR
Set pTargetClone = pTargetSR

'Compare the coordinate system component of the spatial reference
bSREqual = pSourceClone.IsEqual(pTargetClone)

'If the comparison failed, return false and exit
If Not bSREqual Then
    CompareSpatialReferences = False
    Exit Function
End If

'We can also compare the XY precision to ensure the spatial references are equal
Dim pSourceSR2 As ISpatialReference2
Dim bXYIsEqual As Boolean

Set pSourceSR2 = pSourceSR
bXYIsEqual = pSourceSR2.IsXYPrecisionEqual(pTargetSR)

'If the comparison failed, return false and exit
If Not bXYIsEqual Then
    CompareSpatialReferences = False
    Exit Function
End If

CompareSpatialReferences = True

End Function