concave_hull.h

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#pragma once
 
#include <pcl/pcl_config.h>
#ifdef HAVE_QHULL
 
#include <pcl/surface/reconstruction.h> // for MeshConstruction
 
namespace pcl
{
  ////////////////////////////////////////////////////////////////////////////////////////////
  /** \brief @b ConcaveHull (alpha shapes) using libqhull library.
    * \author Aitor Aldoma
    * \ingroup surface
    */
  template<typename PointInT>
  class ConcaveHull : public MeshConstruction<PointInT>
  {
    protected:
      using Ptr = shared_ptr<ConcaveHull<PointInT> >;
      using ConstPtr = shared_ptr<const ConcaveHull<PointInT> >;
 
      using PCLBase<PointInT>::input_;
      using PCLBase<PointInT>::indices_;
      using PCLBase<PointInT>::initCompute;
      using PCLBase<PointInT>::deinitCompute;
 
    public:
      using MeshConstruction<PointInT>::reconstruct;
 
      using PointCloud = pcl::PointCloud<PointInT>;
      using PointCloudPtr = typename PointCloud::Ptr;
      using PointCloudConstPtr = typename PointCloud::ConstPtr;
 
      /** \brief Empty constructor. */
      ConcaveHull () = default;
      
      /** \brief Empty destructor */
      ~ConcaveHull () override = default;
 
      /** \brief Compute a concave hull for all points given 
        *
        * \param points the resultant points lying on the concave hull 
        * \param polygons the resultant concave hull polygons, as a set of
        * vertices. The Vertices structure contains an array of point indices.
        */
      void
      reconstruct (PointCloud &points, 
                   std::vector<pcl::Vertices> &polygons);
 
      /** \brief Compute a concave hull for all points given 
       * \param output the resultant concave hull vertices
       */
      void
      reconstruct (PointCloud &output);
 
      /** \brief Set the alpha value, which limits the size of the resultant
        * hull segments (the smaller the more detailed the hull).  
        *
        * \param alpha positive, non-zero value, defining the maximum length
        * from a vertex to the facet center (center of the voronoi cell).
        */
      inline void
      setAlpha (double alpha)
      {
        alpha_ = alpha;
      }
 
      /** \brief Returns the alpha parameter, see setAlpha(). */
      inline double
      getAlpha ()
      {
        return (alpha_);
      }
 
      /** \brief If set, the voronoi cells center will be saved in _voronoi_centers_
        * \param voronoi_centers
        */
      inline void
      setVoronoiCenters (PointCloudPtr voronoi_centers)
      {
        voronoi_centers_ = voronoi_centers;
      }
 
      /** \brief If keep_information_is set to true the convex hull
        * points keep other information like rgb, normals, ...
        * \param value where to keep the information or not, default is false
        */
      void
      setKeepInformation (bool value)
      {
        keep_information_ = value;
      }
      
      /** \brief Returns the dimensionality (2 or 3) of the calculated hull. */
      inline int
      getDimension () const
      {
        return (dim_);
      }
 
      /** \brief Sets the dimension on the input data, 2D or 3D.
        * \param[in] dimension The dimension of the input data.  If not set, this will be determined automatically.
        */
      void 
      setDimension (int dimension)
      {
        if ((dimension == 2) || (dimension == 3))
          dim_ = dimension;
        else
          PCL_ERROR ("[pcl::%s::setDimension] Invalid input dimension specified!\n", getClassName ().c_str ());
      }
 
      /** \brief Retrieve the indices of the input point cloud that for the convex hull.
        *
        * \note Should only be called after reconstruction was performed and if the ConcaveHull is
        * set to preserve information via setKeepInformation ().
        *
        * \param[out] hull_point_indices The indices of the points forming the point cloud
        */
      void
      getHullPointIndices (pcl::PointIndices &hull_point_indices) const;
 
    protected:
      /** \brief Class get name method. */
      std::string
      getClassName () const override
      {
        return ("ConcaveHull");
      }
 
    protected:
      /** \brief The actual reconstruction method.
        * 
        * \param points the resultant points lying on the concave hull 
        * \param polygons the resultant concave hull polygons, as a set of
        * vertices. The Vertices structure contains an array of point indices.
        */
      void
      performReconstruction (PointCloud &points, 
                             std::vector<pcl::Vertices> &polygons);
 
      void
      performReconstruction (PolygonMesh &output) override;
 
      void
      performReconstruction (std::vector<pcl::Vertices> &polygons) override;
 
      /** \brief The method accepts facets only if the distance from any vertex to the facet->center 
        * (center of the voronoi cell) is smaller than alpha 
        */
      double alpha_{0.0};
 
      /** \brief If set to true, the reconstructed point cloud describing the hull is obtained from 
        * the original input cloud by performing a nearest neighbor search from Qhull output. 
        */
      bool keep_information_{false};
 
      /** \brief the centers of the voronoi cells */
      PointCloudPtr voronoi_centers_{nullptr};
      
      /** \brief the dimensionality of the concave hull */
      int dim_{0};
 
      /** \brief vector containing the point cloud indices of the convex hull points. */
      pcl::PointIndices hull_indices_;
  };
}
 
#ifdef PCL_NO_PRECOMPILE
#include <pcl/surface/impl/concave_hull.hpp>
#endif
 
#endif