[vtkusers] pb trying to input vtkImageData into vtkHedgeHog

[Thomas Deschamps]

Hi vtkUsers

I have a vtkImageData with either 2 or 3 number of scalar components.
In fact it contains the different components of the gradient of 2D and 
3D images.
I tried to use vtkHedgeHog to represent the vector fields, but 
apparently vtkHedgeHog does not accept the vtkImageData pointer as input 
directly.
 
 void   testHedgeHog(vtkImageData * vectorField)
{

    vtkHedgeHog * hedgehog = vtkHedgeHog::New();
    hedgehog -> SetInput( vectorField );
    hedgehog -> SetScaleFactor( *scaleFactor );
    hedgehog -> Update();
    ....
  }

 > vtkHedgeHog (0x85b30f0): No vectors in input data

I would like to know if someone tried to do the same thing than me.
Many thanks.

Thomas