usc.hpp

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 *  $Id: usc.hpp 3755 2011-12-31 23:45:30Z rusu $
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#ifndef PCL_FEATURES_IMPL_USC_HPP_
#define PCL_FEATURES_IMPL_USC_HPP_

#include <pcl/features/usc.h>
#include <pcl/features/shot_common.h>
#include <pcl/common/geometry.h>
#include <pcl/common/angles.h>
#include <pcl/common/utils.h>

template <typename PointInT, typename PointOutT> bool
pcl::UniqueShapeContext<PointInT, PointOutT>::initCompute ()
{
  if (!Feature<PointInT, PointOutT>::initCompute ())
  {
    PCL_ERROR ("[pcl::%s::initCompute] Init failed.\n", getClassName ().c_str ());
    return (false);
  }

  if (search_radius_< min_radius_)
  {
    PCL_ERROR ("[pcl::%s::initCompute] search_radius_ must be GREATER than min_radius_.\n", getClassName ().c_str ());
    return (false);
  }

  // Update descriptor length
  descriptor_length_ = elevation_bins_ * azimuth_bins_ * radius_bins_;

  // Compute radial, elevation and azimuth divisions
  float azimuth_interval = (float) 360 / azimuth_bins_;
  float elevation_interval = (float) 180 / elevation_bins_;

  // Reallocate divisions and volume lut
  radii_interval_.clear ();
  phi_divisions_.clear ();
  theta_divisions_.clear ();
  volume_lut_.clear ();

  // Fills radii interval based on formula (1) in section 2.1 of Frome's paper
  radii_interval_.resize (radius_bins_ + 1);
  for (size_t j = 0; j < radius_bins_ + 1; j++)
    radii_interval_[j] = exp (log (min_radius_) + (((float) j / (radius_bins_)) * log (search_radius_/min_radius_)));

  // Fill theta didvisions of elevation
  theta_divisions_.resize (elevation_bins_+1);
  for (size_t k = 0; k < elevation_bins_+1; k++)
    theta_divisions_[k] = k*elevation_interval;

  // Fill phi didvisions of elevation
  phi_divisions_.resize (azimuth_bins_+1);
  for (size_t l = 0; l < azimuth_bins_+1; l++)
    phi_divisions_[l] = l*azimuth_interval;

  // LookUp Table that contains the volume of all the bins
  // "phi" term of the volume integral
  // "integr_phi" has always the same value so we compute it only one time
  float integr_phi  = pcl::deg2rad (phi_divisions_[1]) - pcl::deg2rad (phi_divisions_[0]);
  // exponential to compute the cube root using pow
  float e = 1.0 / 3.0;    
  // Resize volume look up table
  volume_lut_.resize (radius_bins_ * elevation_bins_ * azimuth_bins_);
  // Fill volumes look up table
  for (size_t j = 0; j < radius_bins_; j++)
  {
    // "r" term of the volume integral
    float integr_r = (radii_interval_[j+1]*radii_interval_[j+1]*radii_interval_[j+1] / 3) - (radii_interval_[j]*radii_interval_[j]*radii_interval_[j]/ 3);
    
    for (size_t k = 0; k < elevation_bins_; k++)
    {
      // "theta" term of the volume integral
      float integr_theta = cos (deg2rad (theta_divisions_[k])) - cos (deg2rad (theta_divisions_[k+1]));
      // Volume
      float V = integr_phi * integr_theta * integr_r;
      // Compute cube root of the computed volume commented for performance but left 
      // here for clarity
      // float cbrt = pow(V, e);
      // cbrt = 1 / cbrt;
      
      for (size_t l = 0; l < azimuth_bins_; l++)
        // Store in lut 1/cbrt
        //volume_lut_[ (l*elevation_bins_*radius_bins_) + k*radius_bins_ + j ] = cbrt;
        volume_lut_[(l*elevation_bins_*radius_bins_) + k*radius_bins_ + j] = 1.0 / pow (V, e);
    }
  }
  return (true);
}

template <typename PointInT, typename PointOutT> bool
pcl::UniqueShapeContext<PointInT, PointOutT>::computePointRF (size_t index, float rf[9])
{
  std::vector<int> nn_indices;
  std::vector<float> nn_dists;
  size_t nb_neighbours = searchForNeighbors ((*indices_)[index], local_radius_, nn_indices, nn_dists);

  // The RF is formed as the SHOT local RF
  if (nb_neighbours < 5)
  {
    //PCL_WARN ("[pcl::%s::computePointRF] Neighborhood has %d vertices which is less than 5, aborting description of point index %d\n!", getClassName ().c_str (), nb_neighbours, (*indices_)[index]);
    return (false);
  }
  std::vector<Eigen::Vector4f, Eigen::aligned_allocator<Eigen::Vector4f> > rf_ (3);
  Eigen::Vector4f central_point = input_->points[(*indices_)[index]].getVector4fMap ();
  central_point[3] = 0;
  pcl::getLocalRF (*surface_, local_radius_, central_point /*(*indices_)[index]*/, nn_indices, nn_dists, rf_);
  for (int d = 0; d < 9; ++d)
    rf[d] = rf_[d/3][d%3];

  return (true);
}

template <typename PointInT, typename PointOutT> void
pcl::UniqueShapeContext<PointInT, PointOutT>::computePointDescriptor (size_t index, float rf[9], std::vector<float> &desc)
{
  pcl::Vector3fMapConst origin = input_->points[(*indices_)[index]].getVector3fMap ();
  const Eigen::Map<Eigen::Vector3f> x_axis (rf);
  const Eigen::Map<Eigen::Vector3f> y_axis (rf + 3);
  const Eigen::Map<Eigen::Vector3f> normal (rf + 6);
  // Find every point within specified search_radius_
  std::vector<int> nn_indices;
  std::vector<float> nn_dists;
  const size_t neighb_cnt = searchForNeighbors ((*indices_)[index], search_radius_, nn_indices, nn_dists);
  // For each point within radius
  for (size_t ne = 0; ne < neighb_cnt; ne++)
  {
    if (pcl::utils::equal(nn_dists[ne], 0.0f))
      continue;
    // Get neighbours coordinates
    Eigen::Vector3f neighbour = surface_->points[nn_indices[ne]].getVector3fMap ();

    // ----- Compute current neighbour polar coordinates -----
    
    // Get distance between the neighbour and the origin
    float r = sqrt (nn_dists[ne]); 
    
    // Project point into the tangent plane
    Eigen::Vector3f proj;
    pcl::geometry::project (neighbour, origin, normal, proj);
    proj -= origin;

    // Normalize to compute the dot product
    proj.normalize ();
    
    // Compute the angle between the projection and the x axis in the interval [0,360] 
    Eigen::Vector3f cross = x_axis.cross (proj);
    float phi = rad2deg (std::atan2 (cross.norm (), x_axis.dot (proj)));
    phi = cross.dot (normal) < 0.f ? (360.0 - phi) : phi;
    Eigen::Vector3f no = neighbour - origin;
    no.normalize ();
    float theta = normal.dot (no);
    theta = pcl::rad2deg (acos (std::min (1.0f, std::max (-1.0f, theta))));

    size_t j = 0;
    size_t k = 0;
    size_t l = 0;

    for (size_t rad = 1; rad < radius_bins_ + 1; rad++) 
    {
      if (r <= radii_interval_[rad])
      {
        j = rad - 1;
        break;
      }
    }

    for (size_t ang = 1; ang < elevation_bins_ + 1; ang++) 
    {
      if (theta <= theta_divisions_[ang]) 
      {
        k = ang - 1;
        break;
      }
    }

    for (size_t ang = 1; ang < azimuth_bins_ + 1; ang++) 
    {
      if (phi <= phi_divisions_[ang]) 
      {
        l = ang - 1;
        break;
      }
    }

    std::vector<int> neighbour_indices;
    std::vector<float> neighbour_didtances;
    float point_density = (float) searchForNeighbors (*surface_, nn_indices[ne], point_density_radius_, neighbour_indices, neighbour_didtances);
    float w = (1.0 / point_density) * volume_lut_[(l*elevation_bins_*radius_bins_) + 
                                                  (k*radius_bins_) + 
                                                  j];
      
    assert (w >= 0.0);
    if (w == std::numeric_limits<float>::infinity ())
      PCL_ERROR ("Shape Context Error INF!\n");
    if (w != w)
      PCL_ERROR ("Shape Context Error IND!\n");
    desc[(l*elevation_bins_*radius_bins_) + (k*radius_bins_) + j] += w;

    assert (desc[(l*elevation_bins_*radius_bins_) + (k*radius_bins_) + j] >= 0);
  } // end for each neighbour
}

template <typename PointInT, typename PointOutT> void
pcl::UniqueShapeContext<PointInT, PointOutT>::computeFeature (PointCloudOut &output)
{
  for (size_t point_index = 0; point_index < indices_->size (); point_index++)
  {
    output[point_index].descriptor.resize (descriptor_length_);
    computePointRF (point_index, output[point_index].rf);
    computePointDescriptor (point_index, output[point_index].rf, output[point_index].descriptor);
  }
}

template <typename PointInT> void
pcl::UniqueShapeContext<PointInT, Eigen::MatrixXf>::computeFeature (pcl::PointCloud<Eigen::MatrixXf> &output)
{
  output.points.resize (indices_->size (), descriptor_length_ + 9);
  for (size_t point_index = 0; point_index < indices_->size (); point_index++)
  {
    computePointRF (point_index, output.points.row (point_index).data ());
    std::vector<float> descriptor (descriptor_length_);
    computePointDescriptor (point_index, output.points.row (point_index).data (), descriptor);
    for (size_t j = 0; j < descriptor_length_; ++j)
      output.points (point_index, 9 + j) = descriptor[j];
  }
}

#define PCL_INSTANTIATE_UniqueShapeContext(T,OutT) template class PCL_EXPORTS pcl::UniqueShapeContext<T,OutT>;

#endif