correspondence_estimation_normal_shooting.hpp

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#ifndef PCL_REGISTRATION_IMPL_CORRESPONDENCE_ESTIMATION_NORMAL_SHOOTING_H_
#define PCL_REGISTRATION_IMPL_CORRESPONDENCE_ESTIMATION_NORMAL_SHOOTING_H_

#include <pcl/registration/correspondence_estimation_normal_shooting.h>

template <typename PointSource, typename PointTarget, typename NormalT> void
pcl::registration::CorrespondenceEstimationNormalShooting<PointSource, PointTarget, NormalT>::determineCorrespondences (
    pcl::Correspondences &correspondences, float max_distance)
{
  if (!initCompute ())
    return;

  if (!target_)
  {
    PCL_WARN ("[pcl::%s::compute] No input target dataset was given!\n", getClassName ().c_str ());
    return;
  }
  correspondences.resize (indices_->size ());

  float min_dist = std::numeric_limits<float>::max ();
  float dist = 0.0;
  int min_index = 0;
  tree_->setInputCloud (target_);

  std::vector<int> nn_indices (k_);
  std::vector<float> nn_dists (k_);

  pcl::Correspondence corr;

  for (size_t i = 0; i < source_normals_->points.size (); i++)
  {
    float *normal = source_normals_->points[i].normal;

    tree_->nearestKSearch (input_->points[i], k_, nn_indices, nn_dists);

    // Among the K nearest neighbours find the one with minimum perpendicular distance to the normal
    min_dist = std::numeric_limits<float>::max ();
    for (size_t j = 0; j < nn_indices.size (); j++)
    {
      int q = nn_indices[j];
      // computing the distance between a point and a line in 3d. 
      // Reference - http://mathworld.wolfram.com/Point-LineDistance3-Dimensional.html
      PointTarget pt;
      pt.x = target_->points[q].x - input_->points[i].x;
      pt.y = target_->points[q].y - input_->points[i].y;
      pt.z = target_->points[q].z - input_->points[i].z;
      Eigen::Vector3d N (normal[0], normal[1], normal[2]);
      Eigen::Vector3d V (pt.x, pt.y, pt.z);
      Eigen::Vector3d C = N.cross (V);
      dist = C.dot (C);
      if (dist < min_dist)
      {
        min_dist = dist;
        min_index = q;
      }
    }
    if (min_dist > max_distance)
      continue;
    corr.index_query = i;
    corr.index_match = min_index;
    corr.distance = min_dist;
    correspondences[i] = corr;
  }
  deinitCompute ();
}

#endif /* PCL_REGISTRATION_IMPL_CORRESPONDENCE_ESTIMATION_NORMAL_SHOOTING_H_ */