ArcObjects Library Reference  (GeoDatabase)    

ISurface.InterpolateShape Method

Interpolates z values for a defined geometric shape.

[Visual Basic 6.0]
Sub InterpolateShape(
    ByVal pShape As IGeometry, _
    ppOutShape As IGeometry, _
    [pStepSize As Variant] _
[Visual Basic .NET]
Public Sub InterpolateShape ( _
    ByVal pShape As IGeometry, _
    ByRef ppOutShape As IGeometry, _
    [ByRef pStepSize As Object] _
public void InterpolateShape (
    IGeometry pShape,
    ref IGeometry ppOutShape,
    ref object pStepSize

Optional Values

pStepSize   To indicate that this parameter is undefined, first define a variable object Missing = Type.Missing; then pass this in as ref Missing.
public void interpolateShape (
    IGeometry pShape,
    IGeometry ppOutShape,
    Object pStepSize
HRESULT InterpolateShape(
  IGeometry* pShape,
  IGeometry** ppOutShape,
  VARIANT* pStepSize


pShape [in]

  pShape is a parameter of type IGeometry

ppOutShape [out]

  ppOutShape is a parameter of type IGeometry

pStepSize [optional]

  pStepSize is a parameter of type VARIANT

  To indicate this parameter is undefined pass a reference to a VARIANT with type VT_ERROR and scode value of DISP_E_PARAMNOTFOUND.

Product Availability

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


The Shape is an input 2D geometry. The method interpolates heights for it from the surface, and outputs the result as 3D geometry into OutShape.

The input geometry can be a point, polyline or polygon. Portions of the input not falling within the interpolation zone of the surface will be clipped. A NULL pointer ('Nothing' in VisualBasic) is returned when the input falls entirely off the surface.

If specified, input polylines and polygons will be densified by the stepSize. This takes place before interpolating heights from the surface. The densification ensures no two vertices are spaced more than stepSize apart.

The stepSize argument isn't very important when the surface is a TIN as the default sampling scheme of using input vertices and triangle edge intersections is sufficient to capture all surface information. If the surface is a raster it becomes more important. Generally, the smaller the interval the greater the detail (unless smaller than 1/2 cellsize), but at an increased cost in processing time and size of resulting geometry. The default stepSize for raster based surface is set equal to the cellsize.

InterpolateShape will handle differences in spatial reference between the input shape and the surface. It will project (a copy of) the input geometry to match the surface for the sake of interpolation. It will then re-project the output geometry so it's the same as the input shape.

See Also

ISurface Interface


InterpolateShape Example