diff --git a/Modules/DiffusionImaging/FiberTracking/Algorithms/itkTractsToVectorImageFilter.cpp b/Modules/DiffusionImaging/FiberTracking/Algorithms/itkTractsToVectorImageFilter.cpp
index fe4df6a770..c0a7253736 100644
--- a/Modules/DiffusionImaging/FiberTracking/Algorithms/itkTractsToVectorImageFilter.cpp
+++ b/Modules/DiffusionImaging/FiberTracking/Algorithms/itkTractsToVectorImageFilter.cpp
@@ -1,832 +1,832 @@
 #include "itkTractsToVectorImageFilter.h"
 
 // VTK
 #include <vtkPolyLine.h>
 #include <vtkCellArray.h>
 #include <vtkCellData.h>
 
 // ITK
 #include <itkTimeProbe.h>
 #include <itkImageRegionIterator.h>
 
 // misc
 #define _USE_MATH_DEFINES
 #include <math.h>
 #include <boost/progress.hpp>
 
 
 namespace itk{
 
 static bool CompareVectorLengths(const vnl_vector_fixed< double, 3 >& v1, const vnl_vector_fixed< double, 3 >& v2)
 {
     return (v1.magnitude()>v2.magnitude());
 }
 
 template< class PixelType >
 TractsToVectorImageFilter< PixelType >::TractsToVectorImageFilter():
     m_AngularThreshold(0.7),
     m_Epsilon(0.999),
     m_MaskImage(NULL),
     m_NormalizeVectors(false),
     m_UseWorkingCopy(true),
     m_UseTrilinearInterpolation(false),
     m_MaxNumDirections(3),
     m_Thres(0.5),
     m_NumDirectionsImage(NULL)
 {
     this->SetNumberOfRequiredOutputs(1);
 }
 
 
 template< class PixelType >
 TractsToVectorImageFilter< PixelType >::~TractsToVectorImageFilter()
 {
 }
 
 
 template< class PixelType >
 vnl_vector_fixed<double, 3> TractsToVectorImageFilter< PixelType >::GetVnlVector(double point[3])
 {
     vnl_vector_fixed<double, 3> vnlVector;
     vnlVector[0] = point[0];
     vnlVector[1] = point[1];
     vnlVector[2] = point[2];
     return vnlVector;
 }
 
 
 template< class PixelType >
 itk::Point<float, 3> TractsToVectorImageFilter< PixelType >::GetItkPoint(double point[3])
 {
     itk::Point<float, 3> itkPoint;
     itkPoint[0] = point[0];
     itkPoint[1] = point[1];
     itkPoint[2] = point[2];
     return itkPoint;
 }
 
 template< class PixelType >
 void TractsToVectorImageFilter< PixelType >::GenerateData()
 {
     mitk::Geometry3D::Pointer geometry = m_FiberBundle->GetGeometry();
 
     // calculate new image parameters
     itk::Vector<double> spacing;
     itk::Point<double> origin;
     itk::Matrix<double, 3, 3> direction;
     ImageRegion<3> imageRegion;
     if (!m_MaskImage.IsNull())
     {
         spacing = m_MaskImage->GetSpacing();
         imageRegion = m_MaskImage->GetLargestPossibleRegion();
         origin = m_MaskImage->GetOrigin();
         direction = m_MaskImage->GetDirection();
     }
     else
     {
         spacing = geometry->GetSpacing();
         origin = geometry->GetOrigin();
         mitk::Geometry3D::BoundsArrayType bounds = geometry->GetBounds();
         origin[0] += bounds.GetElement(0);
         origin[1] += bounds.GetElement(2);
         origin[2] += bounds.GetElement(4);
 
         for (int i=0; i<3; i++)
             for (int j=0; j<3; j++)
                 direction[j][i] = geometry->GetMatrixColumn(i)[j];
         imageRegion.SetSize(0, geometry->GetExtent(0));
         imageRegion.SetSize(1, geometry->GetExtent(1));
         imageRegion.SetSize(2, geometry->GetExtent(2));
 
 
         m_MaskImage = ItkUcharImgType::New();
         m_MaskImage->SetSpacing( spacing );
         m_MaskImage->SetOrigin( origin );
         m_MaskImage->SetDirection( direction );
         m_MaskImage->SetRegions( imageRegion );
         m_MaskImage->Allocate();
         m_MaskImage->FillBuffer(1);
     }
     OutputImageType::RegionType::SizeType outImageSize = imageRegion.GetSize();
     m_OutImageSpacing = m_MaskImage->GetSpacing();
     m_ClusteredDirectionsContainer = ContainerType::New();
 
     // initialize crossings image
     m_CrossingsImage = ItkUcharImgType::New();
     m_CrossingsImage->SetSpacing( spacing );
     m_CrossingsImage->SetOrigin( origin );
     m_CrossingsImage->SetDirection( direction );
     m_CrossingsImage->SetRegions( imageRegion );
     m_CrossingsImage->Allocate();
     m_CrossingsImage->FillBuffer(0);
 
     // initialize num directions image
     m_NumDirectionsImage = ItkUcharImgType::New();
     m_NumDirectionsImage->SetSpacing( spacing );
     m_NumDirectionsImage->SetOrigin( origin );
     m_NumDirectionsImage->SetDirection( direction );
     m_NumDirectionsImage->SetRegions( imageRegion );
     m_NumDirectionsImage->Allocate();
     m_NumDirectionsImage->FillBuffer(0);
 
     // resample fiber bundle
     float minSpacing = 1;
     if(m_OutImageSpacing[0]<m_OutImageSpacing[1] && m_OutImageSpacing[0]<m_OutImageSpacing[2])
         minSpacing = m_OutImageSpacing[0];
     else if (m_OutImageSpacing[1] < m_OutImageSpacing[2])
         minSpacing = m_OutImageSpacing[1];
     else
         minSpacing = m_OutImageSpacing[2];
 
     if (m_UseWorkingCopy)
         m_FiberBundle = m_FiberBundle->GetDeepCopy();
 
     // resample fiber bundle for sufficient voxel coverage
     m_FiberBundle->ResampleFibers(minSpacing/3);
 
     // iterate over all fibers
     vtkSmartPointer<vtkPolyData> fiberPolyData = m_FiberBundle->GetFiberPolyData();
     vtkSmartPointer<vtkCellArray> vLines = fiberPolyData->GetLines();
     vLines->InitTraversal();
     int numFibers = m_FiberBundle->GetNumFibers();
     itk::TimeProbe clock;
     m_DirectionsContainer = ContainerType::New();
 
     if (m_UseTrilinearInterpolation)
         MITK_INFO << "Generating directions from tractogram (trilinear interpolation)";
     else
         MITK_INFO << "Generating directions from tractogram";
 
     boost::progress_display disp(numFibers);
     for( int i=0; i<numFibers; i++ )
     {
         ++disp;
         clock.Start();
         vtkIdType   numPoints(0);
         vtkIdType*  points(NULL);
         vLines->GetNextCell ( numPoints, points );
         if (numPoints<2)
             continue;
 
         itk::Index<3> index; index.Fill(0);
         itk::ContinuousIndex<float, 3> contIndex;
         vnl_vector_fixed<double, 3> dir, wDir;
         itk::Point<float, 3> worldPos;
         vnl_vector<double> v;
         for( int j=0; j<numPoints-1; j++)
         {
             double* temp = fiberPolyData->GetPoint(points[j]);
             worldPos = GetItkPoint(temp);
             v = GetVnlVector(temp);
 
             dir = GetVnlVector(fiberPolyData->GetPoint(points[j+1]))-v;
             dir.normalize();
 
             m_MaskImage->TransformPhysicalPointToIndex(worldPos, index);
             m_MaskImage->TransformPhysicalPointToContinuousIndex(worldPos, contIndex);
 
             if (m_MaskImage->GetPixel(index)==0)
                 continue;
 
             if (!m_UseTrilinearInterpolation)
             {
                 if (index[0] < 0 || (unsigned long)index[0] >= outImageSize[0])
                     continue;
                 if (index[1] < 0 || (unsigned long)index[1] >= outImageSize[1])
                     continue;
                 if (index[2] < 0 || (unsigned long)index[2] >= outImageSize[2])
                     continue;
 
                 unsigned int idx = index[0] + outImageSize[0]*(index[1] + outImageSize[1]*index[2]);
                 DirectionContainerType::Pointer dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, dir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), dir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, dir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
 
                 continue;
             }
 
             float frac_x = contIndex[0] - index[0];
             float frac_y = contIndex[1] - index[1];
             float frac_z = contIndex[2] - index[2];
 
             if (frac_x<0)
             {
                 index[0] -= 1;
                 frac_x += 1;
             }
             if (frac_y<0)
             {
                 index[1] -= 1;
                 frac_y += 1;
             }
             if (frac_z<0)
             {
                 index[2] -= 1;
                 frac_z += 1;
             }
 
             frac_x = 1-frac_x;
             frac_y = 1-frac_y;
             frac_z = 1-frac_z;
 
             // int coordinates inside image?
             if (index[0] < 0 || (unsigned long)index[0] >= outImageSize[0]-1)
                 continue;
             if (index[1] < 0 || (unsigned long)index[1] >= outImageSize[1]-1)
                 continue;
             if (index[2] < 0 || (unsigned long)index[2] >= outImageSize[2]-1)
                 continue;
 
             DirectionContainerType::Pointer dirCont;
             int idx;
             wDir = dir;
             float weight = (  frac_x)*(  frac_y)*(  frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]   + outImageSize[0]*(index[1]  + outImageSize[1]*index[2]  );
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
 
             wDir = dir;
             weight = (  frac_x)*(1-frac_y)*(  frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]   + outImageSize[0]*(index[1]+1+ outImageSize[1]*index[2]  );
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
 
             wDir = dir;
             weight = (  frac_x)*(  frac_y)*(1-frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]   + outImageSize[0]*(index[1]  + outImageSize[1]*index[2]+outImageSize[1]);
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
 
             wDir = dir;
             weight = (  frac_x)*(1-frac_y)*(1-frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]   + outImageSize[0]*(index[1]+1+ outImageSize[1]*index[2]+outImageSize[1]);
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
 
             wDir = dir;
             weight = (1-frac_x)*(  frac_y)*(  frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]+1 + outImageSize[0]*(index[1]  + outImageSize[1]*index[2]  );
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
 
             wDir = dir;
             weight = (1-frac_x)*(  frac_y)*(1-frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]+1 + outImageSize[0]*(index[1]  + outImageSize[1]*index[2]+outImageSize[1]);
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
 
             wDir = dir;
             weight = (1-frac_x)*(1-frac_y)*(  frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]+1 + outImageSize[0]*(index[1]+1+ outImageSize[1]*index[2]  );
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
 
             wDir = dir;
             weight = (1-frac_x)*(1-frac_y)*(1-frac_z);
             if (weight>m_Thres)
             {
                 wDir *= weight;
                 idx = index[0]+1 + outImageSize[0]*(index[1]+1+ outImageSize[1]*index[2]+outImageSize[1]);
                 dirCont = DirectionContainerType::New();
                 if (m_DirectionsContainer->IndexExists(idx))
                 {
                     dirCont = m_DirectionsContainer->GetElement(idx);
                     if (dirCont.IsNull())
                     {
                         dirCont = DirectionContainerType::New();
                         dirCont->InsertElement(0, wDir);
                         m_DirectionsContainer->InsertElement(idx, dirCont);
                     }
                     else
                         dirCont->InsertElement(dirCont->Size(), wDir);
                 }
                 else
                 {
                     dirCont->InsertElement(0, wDir);
                     m_DirectionsContainer->InsertElement(idx, dirCont);
                 }
             }
         }
         clock.Stop();
     }
 
     vtkSmartPointer<vtkCellArray> m_VtkCellArray = vtkSmartPointer<vtkCellArray>::New();
     vtkSmartPointer<vtkPoints>    m_VtkPoints = vtkSmartPointer<vtkPoints>::New();
 
     itk::ImageRegionIterator<ItkUcharImgType> dirIt(m_NumDirectionsImage, m_NumDirectionsImage->GetLargestPossibleRegion());
     itk::ImageRegionIterator<ItkUcharImgType> crossIt(m_CrossingsImage, m_CrossingsImage->GetLargestPossibleRegion());
 
     m_DirectionImageContainer = DirectionImageContainerType::New();
     unsigned int maxNumDirections = 0;
 
     MITK_INFO << "Clustering directions";
     boost::progress_display disp2(outImageSize[0]*outImageSize[1]*outImageSize[2]);
     for(crossIt.GoToBegin(); !crossIt.IsAtEnd(); ++crossIt)
     {
         ++disp2;
         OutputImageType::IndexType index = crossIt.GetIndex();
         int idx = index[0]+(index[1]+index[2]*outImageSize[1])*outImageSize[0];
 
         if (!m_DirectionsContainer->IndexExists(idx))
         {
             ++dirIt;
             continue;
         }
         DirectionContainerType::Pointer dirCont = m_DirectionsContainer->GetElement(idx);
         if (dirCont.IsNull() || index[0] < 0 || (unsigned long)index[0] >= outImageSize[0] || index[1] < 0 || (unsigned long)index[1] >= outImageSize[1] || index[2] < 0 || (unsigned long)index[2] >= outImageSize[2])
         {
             ++dirIt;
             continue;
         }
 
         std::vector< DirectionType > directions;
 
         for (unsigned int i=0; i<dirCont->Size(); i++)
             if (dirCont->ElementAt(i).magnitude()>0.0001)
                 directions.push_back(dirCont->ElementAt(i));
 
         if (!directions.empty())
             directions = FastClustering(directions);
 
         std::sort( directions.begin(), directions.end(), CompareVectorLengths );
 
         if ( directions.size() > maxNumDirections )
         {
             for (unsigned int i=maxNumDirections; i<std::min<unsigned int>(directions.size(), m_MaxNumDirections); i++)
             {
                 ItkDirectionImageType::Pointer directionImage = ItkDirectionImageType::New();
                 directionImage->SetSpacing( spacing );
                 directionImage->SetOrigin( origin );
                 directionImage->SetDirection( direction );
                 directionImage->SetRegions( imageRegion );
                 directionImage->Allocate();
                 Vector< float, 3 > nullVec; nullVec.Fill(0.0);
                 directionImage->FillBuffer(nullVec);
                 m_DirectionImageContainer->InsertElement(i, directionImage);
             }
             maxNumDirections = std::min<unsigned int>(directions.size(), m_MaxNumDirections);
         }
 
         unsigned int numDir = directions.size();
         if (numDir>m_MaxNumDirections)
             numDir = m_MaxNumDirections;
 
         for (unsigned int i=0; i<numDir; i++)
         {
             vtkSmartPointer<vtkPolyLine> container = vtkSmartPointer<vtkPolyLine>::New();
             itk::ContinuousIndex<float, 3> center;
             center[0] = index[0];
             center[1] = index[1];
             center[2] = index[2];
             itk::Point<float> worldCenter;
             m_MaskImage->TransformContinuousIndexToPhysicalPoint( center, worldCenter );
             DirectionType dir = directions.at(i);
 
             // set direction image pixel
             ItkDirectionImageType::Pointer directionImage = m_DirectionImageContainer->GetElement(i);
             Vector< float, 3 > pixel;
             pixel.SetElement(0, dir[0]);
             pixel.SetElement(1, dir[1]);
             pixel.SetElement(2, dir[2]);
             directionImage->SetPixel(index, pixel);
 
             // add direction to vector field (with spacing compensation)
             itk::Point<float> worldStart;
             worldStart[0] = worldCenter[0]-dir[0]/2*minSpacing;
             worldStart[1] = worldCenter[1]-dir[1]/2*minSpacing;
             worldStart[2] = worldCenter[2]-dir[2]/2*minSpacing;
             vtkIdType id = m_VtkPoints->InsertNextPoint(worldStart.GetDataPointer());
             container->GetPointIds()->InsertNextId(id);
             itk::Point<float> worldEnd;
             worldEnd[0] = worldCenter[0]+dir[0]/2*minSpacing;
             worldEnd[1] = worldCenter[1]+dir[1]/2*minSpacing;
             worldEnd[2] = worldCenter[2]+dir[2]/2*minSpacing;
             id = m_VtkPoints->InsertNextPoint(worldEnd.GetDataPointer());
             container->GetPointIds()->InsertNextId(id);
             m_VtkCellArray->InsertNextCell(container);
         }
         dirIt.Set(numDir);
         ++dirIt;
     }
 
     vtkSmartPointer<vtkPolyData> directionsPolyData = vtkSmartPointer<vtkPolyData>::New();
     directionsPolyData->SetPoints(m_VtkPoints);
     directionsPolyData->SetLines(m_VtkCellArray);
     m_OutputFiberBundle = mitk::FiberBundleX::New(directionsPolyData);
 }
 
 
 template< class PixelType >
 std::vector< vnl_vector_fixed< double, 3 > > TractsToVectorImageFilter< PixelType >::FastClustering(std::vector< vnl_vector_fixed< double, 3 > >& inDirs)
 {
     std::vector< vnl_vector_fixed< double, 3 > > outDirs;
     if (inDirs.empty())
         return outDirs;
     vnl_vector_fixed< double, 3 > oldMean, currentMean, workingMean;
 
     std::vector< vnl_vector_fixed< double, 3 > > normalizedDirs;
     std::vector< int > touched;
     for (unsigned int i=0; i<inDirs.size(); i++)
     {
         normalizedDirs.push_back(inDirs[i]);
         normalizedDirs.back().normalize();
     }
 
     // initialize
     float max = 0.0;
     touched.resize(inDirs.size(), 0);
     bool free = true;
     currentMean = inDirs[0];  // initialize first seed
     while (free)
     {
         oldMean.fill(0.0);
 
         // start mean-shift clustering
         float angle = 0.0;
         int counter = 0;
         while ((currentMean-oldMean).magnitude()>0.0001)
         {
             counter = 0;
             oldMean = currentMean;
             workingMean = oldMean;
             workingMean.normalize();
             currentMean.fill(0.0);
             for (unsigned int i=0; i<normalizedDirs.size(); i++)
             {
                 angle = dot_product(workingMean, normalizedDirs[i]);
                 if (angle>=m_AngularThreshold)
                 {
                     currentMean += inDirs[i];
                     touched[i] = 1;
                     counter++;
                 }
                 else if (-angle>=m_AngularThreshold)
                 {
                     currentMean -= inDirs[i];
                     touched[i] = 1;
                     counter++;
                 }
             }
         }
 
         // found stable mean
         if (counter>0)
         {
             currentMean /= counter;
             float mag = currentMean.magnitude();
 
             if (mag>0)
             {
                 if (mag>max)
                     max = mag;
 
                 outDirs.push_back(currentMean);
             }
         }
 
         // find next unused seed
         free = false;
         for (unsigned int i=0; i<touched.size(); i++)
             if (touched[i]==0)
             {
                 currentMean = inDirs[i];
                 free = true;
             }
     }
 
     if (m_NormalizeVectors)
         for (unsigned int i=0; i<outDirs.size(); i++)
             outDirs[i].normalize();
     else if (max>0)
         for (unsigned int i=0; i<outDirs.size(); i++)
             outDirs[i] /= max;
 
     if (inDirs.size()==outDirs.size())
         return outDirs;
     else
         return FastClustering(outDirs);
 }
 
 
 template< class PixelType >
 std::vector< vnl_vector_fixed< double, 3 > > TractsToVectorImageFilter< PixelType >::Clustering(std::vector< vnl_vector_fixed< double, 3 > >& inDirs)
 {
     std::vector< vnl_vector_fixed< double, 3 > > outDirs;
     if (inDirs.empty())
         return outDirs;
     vnl_vector_fixed< double, 3 > oldMean, currentMean, workingMean;
 
     std::vector< vnl_vector_fixed< double, 3 > > normalizedDirs;
     std::vector< int > touched;
-    for (int i=0; i<inDirs.size(); i++)
+    for (std::size_t i=0; i<inDirs.size(); i++)
     {
         normalizedDirs.push_back(inDirs[i]);
         normalizedDirs.back().normalize();
     }
 
     // initialize
     float max = 0.0;
     touched.resize(inDirs.size(), 0);
-    for (int j=0; j<inDirs.size(); j++)
+    for (std::size_t j=0; j<inDirs.size(); j++)
     {
         currentMean = inDirs[j];
         oldMean.fill(0.0);
 
         // start mean-shift clustering
         float angle = 0.0;
         int counter = 0;
         while ((currentMean-oldMean).magnitude()>0.0001)
         {
             counter = 0;
             oldMean = currentMean;
             workingMean = oldMean;
             workingMean.normalize();
             currentMean.fill(0.0);
-            for (int i=0; i<normalizedDirs.size(); i++)
+            for (std::size_t i=0; i<normalizedDirs.size(); i++)
             {
                 angle = dot_product(workingMean, normalizedDirs[i]);
                 if (angle>=m_AngularThreshold)
                 {
                     currentMean += inDirs[i];
                     counter++;
                 }
                 else if (-angle>=m_AngularThreshold)
                 {
                     currentMean -= inDirs[i];
                     counter++;
                 }
             }
         }
 
         // found stable mean
         if (counter>0)
         {
             bool add = true;
             vnl_vector_fixed< double, 3 > normMean = currentMean;
             normMean.normalize();
-            for (int i=0; i<outDirs.size(); i++)
+            for (std::size_t i=0; i<outDirs.size(); i++)
             {
                 vnl_vector_fixed< double, 3 > dir = outDirs[i];
                 dir.normalize();
                 if ((normMean-dir).magnitude()<=0.0001)
                 {
                     add = false;
                     break;
                 }
             }
 
             currentMean /= counter;
             if (add)
             {
                 float mag = currentMean.magnitude();
                 if (mag>0)
                 {
                     if (mag>max)
                         max = mag;
 
                     outDirs.push_back(currentMean);
                 }
             }
         }
     }
 
     if (m_NormalizeVectors)
-        for (int i=0; i<outDirs.size(); i++)
+        for (std::size_t i=0; i<outDirs.size(); i++)
             outDirs[i].normalize();
     else if (max>0)
-        for (int i=0; i<outDirs.size(); i++)
+        for (std::size_t i=0; i<outDirs.size(); i++)
             outDirs[i] /= max;
 
     if (inDirs.size()==outDirs.size())
         return outDirs;
     else
         return FastClustering(outDirs);
 }
 
 
 template< class PixelType >
 TractsToVectorImageFilter< PixelType >::DirectionContainerType::Pointer TractsToVectorImageFilter< PixelType >::MeanShiftClustering(DirectionContainerType::Pointer dirCont)
 {
     DirectionContainerType::Pointer container = DirectionContainerType::New();
 
     float max = 0;
     for (DirectionContainerType::ConstIterator it = dirCont->Begin(); it!=dirCont->End(); ++it)
     {
         vnl_vector_fixed<double, 3> mean = ClusterStep(dirCont, it.Value());
 
         if (mean.is_zero())
             continue;
         bool addMean = true;
 
         for (DirectionContainerType::ConstIterator it2 = container->Begin(); it2!=container->End(); ++it2)
         {
             vnl_vector_fixed<double, 3> dir = it2.Value();
             float angle = fabs(dot_product(mean, dir)/(mean.magnitude()*dir.magnitude()));
             if (angle>=m_Epsilon)
             {
                 addMean = false;
                 break;
             }
         }
 
         if (addMean)
         {
             if (m_NormalizeVectors)
                 mean.normalize();
             else if (mean.magnitude()>max)
                 max = mean.magnitude();
             container->InsertElement(container->Size(), mean);
         }
     }
 
     // max normalize voxel directions
     if (max>0 && !m_NormalizeVectors)
-        for (int i=0; i<container->Size(); i++)
+        for (std::size_t i=0; i<container->Size(); i++)
             container->ElementAt(i) /= max;
 
     if (container->Size()<dirCont->Size())
         return MeanShiftClustering(container);
     else
         return container;
 }
 
 
 template< class PixelType >
 vnl_vector_fixed<double, 3> TractsToVectorImageFilter< PixelType >::ClusterStep(DirectionContainerType::Pointer dirCont, vnl_vector_fixed<double, 3> currentMean)
 {
     vnl_vector_fixed<double, 3> newMean; newMean.fill(0);
 
     for (DirectionContainerType::ConstIterator it = dirCont->Begin(); it!=dirCont->End(); ++it)
     {
         vnl_vector_fixed<double, 3> dir = it.Value();
         float angle = dot_product(currentMean, dir)/(currentMean.magnitude()*dir.magnitude());
         if (angle>=m_AngularThreshold)
             newMean += dir;
         else if (-angle>=m_AngularThreshold)
             newMean -= dir;
     }
 
     if (fabs(dot_product(currentMean, newMean)/(currentMean.magnitude()*newMean.magnitude()))>=m_Epsilon || newMean.is_zero())
         return newMean;
     else
         return ClusterStep(dirCont, newMean);
 }
 }