uniform_sampling.hpp

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#ifndef PCL_KEYPOINTS_UNIFORM_SAMPLING_IMPL_H_
#define PCL_KEYPOINTS_UNIFORM_SAMPLING_IMPL_H_

#include <pcl/common/common.h>
#include <pcl/keypoints/uniform_sampling.h>

template <typename PointInT> void
pcl::UniformSampling<PointInT>::detectKeypoints (PointCloudOut &output)
{
  // Has the input dataset been set already?
  if (!input_)
  {
    PCL_WARN ("[pcl::%s::detectKeypoints] No input dataset given!\n", getClassName ().c_str ());
    output.width = output.height = 0;
    output.points.clear ();
    return;
  }

  output.height       = 1;                    // downsampling breaks the organized structure
  output.is_dense     = true;                 // we filter out invalid points

  Eigen::Vector4f min_p, max_p;
  // Get the minimum and maximum dimensions
  pcl::getMinMax3D<PointInT>(*input_, min_p, max_p);

  // Compute the minimum and maximum bounding box values
  min_b_[0] = static_cast<int> (floor (min_p[0] * inverse_leaf_size_[0]));
  max_b_[0] = static_cast<int> (floor (max_p[0] * inverse_leaf_size_[0]));
  min_b_[1] = static_cast<int> (floor (min_p[1] * inverse_leaf_size_[1]));
  max_b_[1] = static_cast<int> (floor (max_p[1] * inverse_leaf_size_[1]));
  min_b_[2] = static_cast<int> (floor (min_p[2] * inverse_leaf_size_[2]));
  max_b_[2] = static_cast<int> (floor (max_p[2] * inverse_leaf_size_[2]));

  // Compute the number of divisions needed along all axis
  div_b_ = max_b_ - min_b_ + Eigen::Vector4i::Ones ();
  div_b_[3] = 0;

  // Clear the leaves
  leaves_.clear ();

  // Set up the division multiplier
  divb_mul_ = Eigen::Vector4i (1, div_b_[0], div_b_[0] * div_b_[1], 0);

  // First pass: build a set of leaves with the point index closest to the leaf center
  for (size_t cp = 0; cp < indices_->size (); ++cp)
  {
    if (!input_->is_dense)
      // Check if the point is invalid
      if (!pcl_isfinite (input_->points[(*indices_)[cp]].x) || 
          !pcl_isfinite (input_->points[(*indices_)[cp]].y) || 
          !pcl_isfinite (input_->points[(*indices_)[cp]].z))
        continue;

    Eigen::Vector4i ijk = Eigen::Vector4i::Zero ();
    ijk[0] = static_cast<int> (floor (input_->points[(*indices_)[cp]].x * inverse_leaf_size_[0]));
    ijk[1] = static_cast<int> (floor (input_->points[(*indices_)[cp]].y * inverse_leaf_size_[1]));
    ijk[2] = static_cast<int> (floor (input_->points[(*indices_)[cp]].z * inverse_leaf_size_[2]));

    // Compute the leaf index
    int idx = (ijk - min_b_).dot (divb_mul_);
    Leaf& leaf = leaves_[idx];
    // First time we initialize the index
    if (leaf.idx == -1)
    {
      leaf.idx = (*indices_)[cp];
      continue;
    }

    // Check to see if this point is closer to the leaf center than the previous one we saved
    float diff_cur   = (input_->points[(*indices_)[cp]].getVector4fMap () - ijk.cast<float> ()).squaredNorm ();
    float diff_prev  = (input_->points[leaf.idx].getVector4fMap ()        - ijk.cast<float> ()).squaredNorm ();

    // If current point is closer, copy its index instead
    if (diff_cur < diff_prev)
      leaf.idx = (*indices_)[cp];
  }

  // Second pass: go over all leaves and copy data
  output.points.resize (leaves_.size ());
  int cp = 0;

  for (typename boost::unordered_map<size_t, Leaf>::const_iterator it = leaves_.begin (); it != leaves_.end (); ++it)
    output.points[cp++] = it->second.idx;
  output.width = static_cast<uint32_t> (output.points.size ());
}

#define PCL_INSTANTIATE_UniformSampling(T) template class PCL_EXPORTS pcl::UniformSampling<T>;

#endif    // PCL_KEYPOINTS_UNIFORM_SAMPLING_IMPL_H_