// calculate distances and sort them
         std::vector<Clustering::ClusterDistance>   distances;
         distances.resize(previousClusters.size()*currentClusters.size());
         for (int i=0; i< previousClusters.size(); i++)
         {

             for(int j=0; j < currentClusters.size(); j++)
             {
                 int index = j + i * currentClusters.size();
                 distances[index] = Clustering::ClusterDistance( cv::norm(previousClusters[i].m_Properties.m_Center - currentClusters[j].m_Properties.m_Center), previousClusters[i], currentClusters[j] );
             }
         }