[Insight-users] how to change propagation speed in segmentationlevelsetfunction class?

[ning qian]

Hi, all, I just started hacking in itk. I am trying to change the 
propagation speed in segmentation levelset. I derived my class from 
segmentationlevelsetfunction and defined my PropagationSpeed() function as 
follows:

PropagationSpeed(const NeighborhoodType &neighborhood,
                   const FloatOffsetType &offset, GlobalDataStruct *) const
{
  IndexType idx = neighborhood.GetIndex();
  ContinuousIndexType cdx;
  for (unsigned i = 0; i < ImageDimension; ++i)
    {
    cdx[i] = static_cast<double>(idx[i]) - offset[i];
    }
  if ( m_Interpolator->IsInsideBuffer(cdx) )
    {
    return (static_cast<ScalarValueType>(
              m_Interpolator->EvaluateAtContinuousIndex(cdx)));
    }
  else return ( static_cast<ScalarValueType>(m_PropImage->GetPixel(idx)) );
}


where m_PropImage is a new member I defined for the propagation speed. But 
when I ran the simulation using examples, it seems that the results did not 
change at all as using originally defined m_SpeedImage. Besides this change, 
do I need to make any other modifications?

Thanks a lot for your help.

Best, Ning