[Insight-users] Problem computing final metric value

[motes motes]

I have a class Processor looking like this (Processor.h):

  template <typename J, typename M, typename I, typename O, typename T>
  class Processor {
  public:

    // ...

    // itk types
    typedef itk::ImageRegistrationMethod<FixedImageType,
MovingImageType >
RegistrationMethodType;

    Processor ();
    virtual ~Processor ();


   // Setting up the itk componenets


    void Start();

    double GetFinalMetricValue() {
      ParametersType params = registrationMethod->GetLastTransformParameters();
       double dd = registrationMethod->GetOptimizer()->GetValue(params);
      return dd;
    }

  private:
    typename RegistrationMethodType::Pointer registrationMethod;
  };

In Processor.cpp Start() looks like this:


  template <typename J, typename M, typename I, typename O, typename T>
  void
  Processor<J,M,I,O,T>::Start() {
    try {
      this->registrationMethod->Update();
    }
    catch( itk::ExceptionObject & err ) {
      std::cerr << "ExceptionObject caught !" << std::endl;
      std::cerr << err << std::endl;
    }

    ParametersType params = registrationMethod->GetLastTransformParameters();
    double value = registrationMethod->GetOptimizer()->GetValue(params);
    std::cout << "final val = " << value << std::endl;

  }

I then run the processor like:

Processor<......> processor;
processor.Start();
processor.GetFinalMetricValue();

The call:

processor.Start();

works fine but the call:

processor.GetFinalMetricValue();

gives a segmentation error.  The problem is this line in GetFinalMetricValue():

       double dd = registrationMethod->GetOptimizer()->GetValue(params);



Why is it possible to compute the metric value in Start() but not in
the GetFinalMetricValue() ? Is some of the fields in the Optimizer
dealocated after the Start() call?