Added 4pcs and k-4pcs registration methods as proposed by Aiger et al…

…. (2007) and Theiler et al. (2014)

Commit is together with fast transformation estimation to speed up the calculation using a minimum number of 3 points (planar case)

registration/include/pcl/registration/impl/correspondence_estimation_k4pcs.hpp

@@ -73,10 +73,10 @@ pcl::registration::CorrespondenceEstimationK4PCS <PointSource, PointTarget, Norm
   pcl::registration::CorrespondenceEstimation4PCS <PointSource, PointTarget, NormalT, Scalar>::initCompute ();
 
   // set the threshold values with respect to keypoint charactersitics
-  max_pair_diff_ = delta_ * 1.414f; // diff between 2 points of delta_ accuracy (old: 1.f, new: 1.414f)
-  coincidation_limit_ = delta_ * 2.828f; // ~ diff between diff of 2 points (old: 4.f, new: 2.828f)
-  max_edge_diff_ = delta_ * 3.f; // diff between 2 points + some inaccuracy due to quadruple orientation (old: 4.f, new: 3.f)
-  max_mse_ = std::powf (delta_ * 4.f, 2.f); // diff between 2 points + some registration inaccuracy (old: 5.f, new: 4.f)
+  max_pair_diff_ = delta_ * 1.414f; // diff between 2 points of delta_ accuracy
+  coincidation_limit_ = delta_ * 2.828f; // ~ diff between diff of 2 points
+  max_edge_diff_ = delta_ * 3.f; // diff between 2 points + some inaccuracy due to quadruple orientation
+  max_mse_ = std::powf (delta_ * 4.f, 2.f); // diff between 2 points + some registration inaccuracy
   max_inlier_dist_sqr_ = std::powf (10.f * delta_, 2.f); // set rel. large, because MSAC is used (truncated residual score function)
 
   // check use of translation costs and calculate upper boundary if not set by user