How to orthorectify an image

public static void OrthorectifyImage(IRasterDataset2 rpcDataset, IRasterDataset
    demDataset)
{
    //rpcDataset—Represents a raster dataset that has RPC information.
    //demDataset—Represents a raster dataset opened from a DEM of the same area.

    //Get the RPCXform from the raster dataset.
    IRaster2 raster = (IRaster2)rpcDataset.CreateFullRaster();
    IGeodataXform rpcXform = raster.GeodataXform;

    //Set the DEM, and so on.
    ISensorXform sensor = (ISensorXform)rpcXform;
    sensor.DEM = demDataset.CreateDefaultRaster();
    sensor.CorrectGeoid = true;

    //Save the result.
    ISaveAs saveas = (ISaveAs)raster;
    saveas.SaveAs(@"c:\temp\orthorectify_output.img", null, "IMAGINE Image");
}

Public Shared Sub OrthorectifyImage(ByVal rpcDataset As IRasterDataset2, ByVal demDataset As IRasterDataset)

'rpcDataset—Represents a raster dataset that has RPC information.
'demDataset—Represents a raster dataset opened from a DEM of the same area.

'Get the RPCXform from the raster dataset.
Dim raster As IRaster2 = CType(rpcDataset.CreateFullRaster(), IRaster2)
Dim rpcXform As IGeodataXform = raster.GeodataXform

'Set the DEM, and so on.
Dim sensor As ISensorXform = CType(rpcXform, ISensorXform)
sensor.DEM = demDataset.CreateDefaultRaster()
sensor.CorrectGeoid = True

'Save the result.
Dim saveas As ISaveAs = CType(raster, ISaveAs)
saveas.SaveAs("c:\temp\orthorectify_output.img", Nothing, "IMAGINE Image")

End Sub