progressive_morphological_filter.hpp

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#ifndef PCL_SEGMENTATION_PROGRESSIVE_MORPHOLOGICAL_FILTER_HPP_
#define PCL_SEGMENTATION_PROGRESSIVE_MORPHOLOGICAL_FILTER_HPP_
 
#include <pcl/common/common.h>
#include <pcl/common/io.h>
#include <pcl/filters/morphological_filter.h>
#include <pcl/segmentation/progressive_morphological_filter.h>
#include <pcl/point_cloud.h>
#include <pcl/point_types.h>
 
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointT>
pcl::ProgressiveMorphologicalFilter<PointT>::ProgressiveMorphologicalFilter () :
  max_window_size_ (33),
  slope_ (0.7f),
  max_distance_ (10.0f),
  initial_distance_ (0.15f),
  cell_size_ (1.0f),
  base_ (2.0f),
  exponential_ (true)
{
}
 
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointT>
pcl::ProgressiveMorphologicalFilter<PointT>::~ProgressiveMorphologicalFilter () = default;
 
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointT> void
pcl::ProgressiveMorphologicalFilter<PointT>::extract (Indices& ground)
{
  bool segmentation_is_possible = initCompute ();
  if (!segmentation_is_possible)
  {
    deinitCompute ();
    return;
  }
 
  // Compute the series of window sizes and height thresholds
  std::vector<float> height_thresholds;
  std::vector<float> window_sizes;
  int iteration = 0;
  float window_size = 0.0f;
  float height_threshold = 0.0f;
 
  while (window_size < max_window_size_)
  {
    // Determine the initial window size.
    if (exponential_)
      window_size = cell_size_ * (2.0f * std::pow (base_, iteration) + 1.0f);
    else
      window_size = cell_size_ * (2.0f * (iteration+1) * base_ + 1.0f);
 
    // Calculate the height threshold to be used in the next iteration.
    if (iteration == 0)
      height_threshold = initial_distance_;
    else
      height_threshold = slope_ * (window_size - window_sizes[iteration-1]) * cell_size_ + initial_distance_;
 
    // Enforce max distance on height threshold
    if (height_threshold > max_distance_)
      height_threshold = max_distance_;
 
    window_sizes.push_back (window_size);
    height_thresholds.push_back (height_threshold);
 
    iteration++;
  }
 
  // Ground indices are initially limited to those points in the input cloud we
  // wish to process
  ground = *indices_;
 
  // Progressively filter ground returns using morphological open
  for (std::size_t i = 0; i < window_sizes.size (); ++i)
  {
    PCL_DEBUG ("      Iteration %d (height threshold = %f, window size = %f)...",
               i, height_thresholds[i], window_sizes[i]);
 
    // Limit filtering to those points currently considered ground returns
    typename pcl::PointCloud<PointT>::Ptr cloud (new pcl::PointCloud<PointT>);
    pcl::copyPointCloud<PointT> (*input_, ground, *cloud);
 
    // Create new cloud to hold the filtered results. Apply the morphological
    // opening operation at the current window size.
    typename pcl::PointCloud<PointT>::Ptr cloud_f (new pcl::PointCloud<PointT>);
    pcl::applyMorphologicalOperator<PointT> (cloud, window_sizes[i], MORPH_OPEN, *cloud_f);
 
    // Find indices of the points whose difference between the source and
    // filtered point clouds is less than the current height threshold.
    Indices pt_indices;
    for (std::size_t p_idx = 0; p_idx < ground.size (); ++p_idx)
    {
      float diff = (*cloud)[p_idx].z - (*cloud_f)[p_idx].z;
      if (diff < height_thresholds[i])
        pt_indices.push_back (ground[p_idx]);
    }
 
    // Ground is now limited to pt_indices
    ground.swap (pt_indices);
 
    PCL_DEBUG ("ground now has %d points\n", ground.size ());
  }
 
  deinitCompute ();
}
 
#define PCL_INSTANTIATE_ProgressiveMorphologicalFilter(T) template class pcl::ProgressiveMorphologicalFilter<T>;
 
#endif    // PCL_SEGMENTATION_PROGRESSIVE_MORPHOLOGICAL_FILTER_HPP_