fpfh_omp.hpp

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#pragma once
 
#include <pcl/features/fpfh_omp.h>
 
#include <pcl/common/point_tests.h> // for pcl::isFinite
 
#include <numeric>
 
 
//////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointInT, typename PointNT, typename PointOutT> void
pcl::FPFHEstimationOMP<PointInT, PointNT, PointOutT>::setNumberOfThreads (unsigned int nr_threads)
{
  if (nr_threads == 0)
#ifdef _OPENMP
    threads_ = omp_get_num_procs();
#else
    threads_ = 1;
#endif
  else
    threads_ = nr_threads;
}
 
//////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointInT, typename PointNT, typename PointOutT> void
pcl::FPFHEstimationOMP<PointInT, PointNT, PointOutT>::computeFeature (PointCloudOut &output)
{
  std::vector<int> spfh_indices_vec;
  std::vector<int> spfh_hist_lookup (surface_->size ());
 
  // Build a list of (unique) indices for which we will need to compute SPFH signatures
  // (We need an SPFH signature for every point that is a neighbor of any point in input_[indices_])
  if (surface_ != input_ ||
      indices_->size () != surface_->size ())
  { 
    pcl::Indices nn_indices (k_); // \note These resizes are irrelevant for a radiusSearch ().
    std::vector<float> nn_dists (k_); 
 
    std::set<int> spfh_indices_set;
    for (std::size_t idx = 0; idx < indices_->size (); ++idx)
    {
      int p_idx = (*indices_)[idx];
      if (!isFinite ((*input_)[p_idx]) ||
          this->searchForNeighbors (p_idx, search_parameter_, nn_indices, nn_dists) == 0)
        continue;
 
      spfh_indices_set.insert (nn_indices.begin (), nn_indices.end ());
    }
    spfh_indices_vec.resize (spfh_indices_set.size ());
    std::copy (spfh_indices_set.cbegin (), spfh_indices_set.cend (), spfh_indices_vec.begin ());
  }
  else
  {
    // Special case: When a feature must be computed at every point, there is no need for a neighborhood search
    spfh_indices_vec.resize (indices_->size ());
    std::iota(spfh_indices_vec.begin (), spfh_indices_vec.end (),
              static_cast<decltype(spfh_indices_vec)::value_type>(0));
  }
 
  // Initialize the arrays that will store the SPFH signatures
  const auto data_size = spfh_indices_vec.size ();
  hist_f1_.setZero (data_size, nr_bins_f1_);
  hist_f2_.setZero (data_size, nr_bins_f2_);
  hist_f3_.setZero (data_size, nr_bins_f3_);
 
  pcl::Indices nn_indices (k_); // \note These resizes are irrelevant for a radiusSearch ().
  std::vector<float> nn_dists (k_); 
 
  // Compute SPFH signatures for every point that needs them
 
#pragma omp parallel for \
  default(none) \
  shared(spfh_hist_lookup, spfh_indices_vec) \
  firstprivate(nn_indices, nn_dists) \
  num_threads(threads_)
  for (std::ptrdiff_t i = 0; i < static_cast<std::ptrdiff_t> (spfh_indices_vec.size ()); ++i)
  {
    // Get the next point index
    int p_idx = spfh_indices_vec[i];
 
    // Find the neighborhood around p_idx
    if (!isFinite ((*surface_)[p_idx]) ||
        this->searchForNeighbors (*surface_, p_idx, search_parameter_, nn_indices, nn_dists) == 0)
      continue;
 
    // Estimate the SPFH signature around p_idx
    this->computePointSPFHSignature (*surface_, *normals_, p_idx, i, nn_indices, hist_f1_, hist_f2_, hist_f3_);
 
    // Populate a lookup table for converting a point index to its corresponding row in the spfh_hist_* matrices
    spfh_hist_lookup[p_idx] = i;
  }
 
  // Initialize the array that will store the FPFH signature
  int nr_bins = nr_bins_f1_ + nr_bins_f2_ + nr_bins_f3_;
 
  nn_indices.clear();
  nn_dists.clear();
 
  // Iterate over the entire index vector
#pragma omp parallel for \
  default(none) \
  shared(nr_bins, output, spfh_hist_lookup) \
  firstprivate(nn_dists, nn_indices) \
  num_threads(threads_)
  for (std::ptrdiff_t idx = 0; idx < static_cast<std::ptrdiff_t> (indices_->size ()); ++idx)
  {
    // Find the indices of point idx's neighbors...
    if (!isFinite ((*input_)[(*indices_)[idx]]) ||
        this->searchForNeighbors ((*indices_)[idx], search_parameter_, nn_indices, nn_dists) == 0)
    {
      for (int d = 0; d < nr_bins; ++d)
        output[idx].histogram[d] = std::numeric_limits<float>::quiet_NaN ();
 
      output.is_dense = false;
      continue;
    }
 
 
    // ... and remap the nn_indices values so that they represent row indices in the spfh_hist_* matrices 
    // instead of indices into surface_->points
    for (auto &nn_index : nn_indices)
      nn_index = spfh_hist_lookup[nn_index];
 
    // Compute the FPFH signature (i.e. compute a weighted combination of local SPFH signatures) ...
    Eigen::VectorXf fpfh_histogram = Eigen::VectorXf::Zero (nr_bins);
    weightPointSPFHSignature (hist_f1_, hist_f2_, hist_f3_, nn_indices, nn_dists, fpfh_histogram);
 
    // ...and copy it into the output cloud
    for (int d = 0; d < nr_bins; ++d)
      output[idx].histogram[d] = fpfh_histogram[d];
  }
 
}
 
#define PCL_INSTANTIATE_FPFHEstimationOMP(T,NT,OutT) template class PCL_EXPORTS pcl::FPFHEstimationOMP<T,NT,OutT>;