Added method to get point indices from convex_hull

surface/include/pcl/surface/concave_hull.h

@@ -157,6 +157,16 @@ namespace pcl
           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
@@ -197,6 +207,9 @@ namespace pcl
 
       /** \brief the dimensionality of the concave hull */
       int dim_;
+
+      /** \brief vector containing the point cloud indices of the convex hull points. */
+      pcl::PointIndices hull_indices_;
   };
 }
 

surface/include/pcl/surface/convex_hull.h

@@ -166,6 +166,14 @@ namespace pcl
         return (dimension_);
       }
 
+      /** \brief Retrieve the indices of the input point cloud that for the convex hull.
+        *
+        * \note Should only be called after reconstruction was performed.
+        * \param[out] hull_point_indices The indices of the points forming the point cloud
+        */
+      void
+      getHullPointIndices (pcl::PointIndices &hull_point_indices) const;
+
     protected:
       /** \brief The actual reconstruction method. 
         * 
@@ -255,6 +263,9 @@ namespace pcl
       /* \brief z-axis - for checking valid projections. */
       const Eigen::Vector3d z_axis_;
 
+      /* \brief vector containing the point cloud indices of the convex hull points. */
+      pcl::PointIndices hull_indices_;
+
       public:
         EIGEN_MAKE_ALIGNED_OPERATOR_NEW
   };

surface/include/pcl/surface/impl/concave_hull.hpp

@@ -579,18 +579,18 @@ pcl::ConcaveHull<PointInT>::performReconstruction (PointCloud &alpha_shape, std:
     distances.resize (1);
 
     // for each point in the concave hull, search for the nearest neighbor in the original point cloud
-
-    std::vector<int> indices;
-    indices.resize (alpha_shape.points.size ());
+    hull_indices_.header = input_->header;
+    hull_indices_.indices.clear ();
+    hull_indices_.indices.reserve (alpha_shape.points.size ());
 
     for (size_t i = 0; i < alpha_shape.points.size (); i++)
     {
       tree.nearestKSearch (alpha_shape.points[i], 1, neighbor, distances);
-      indices[i] = neighbor[0];
+      hull_indices_.indices.push_back (neighbor[0]);
     }
 
     // replace point with the closest neighbor in the original point cloud
-    pcl::copyPointCloud (*input_, indices, alpha_shape);
+    pcl::copyPointCloud (*input_, hull_indices_.indices, alpha_shape);
   }
 }
 #ifdef __GNUC__
@@ -617,6 +617,12 @@ pcl::ConcaveHull<PointInT>::performReconstruction (std::vector<pcl::Vertices> &p
   performReconstruction (hull_points, polygons);
 }
 
+//////////////////////////////////////////////////////////////////////////////////////////
+template <typename PointInT> void
+pcl::ConcaveHull<PointInT>::getHullPointIndices (pcl::PointIndices &hull_point_indices) const
+{
+  hull_point_indices = hull_indices_;
+}
 
 #define PCL_INSTANTIATE_ConcaveHull(T) template class PCL_EXPORTS pcl::ConcaveHull<T>;
 

surface/include/pcl/surface/impl/convex_hull.hpp

@@ -260,8 +260,13 @@ pcl::ConvexHull<PointInT>::performReconstruction2D (PointCloud &hull, std::vecto
   polygons.resize (1);
   polygons[0].vertices.resize (hull.points.size ());
 
+  hull_indices_.header = input_->header;
+  hull_indices_.indices.clear ();
+  hull_indices_.indices.reserve (hull.points.size ());
+
   for (int j = 0; j < static_cast<int> (hull.points.size ()); j++)
   {
+    hull_indices_.indices.push_back ((*indices_)[idx_points[j].first]);
     hull.points[j] = input_->points[(*indices_)[idx_points[j].first]];
     polygons[0].vertices[j] = static_cast<unsigned int> (j);
   }
@@ -357,10 +362,15 @@ pcl::ConvexHull<PointInT>::performReconstruction3D (
   ++max_vertex_id;
   std::vector<int> qhid_to_pcidx (max_vertex_id);
 
+  hull_indices_.header = input_->header;
+  hull_indices_.indices.clear ();
+  hull_indices_.indices.reserve (num_vertices);
+
   FORALLvertices
   {
-    // Add vertices to hull point_cloud
-    hull.points[i] = input_->points[(*indices_)[qh_pointid (vertex->point)]];
+    // Add vertices to hull point_cloud and store index
+    hull_indices_.indices.push_back ((*indices_)[qh_pointid (vertex->point)]);
+    hull.points[i] = input_->points[(*indices_)[hull_indices_.indices.back ()]];
 
     qhid_to_pcidx[vertex->id] = i; // map the vertex id of qhull to the point cloud index
     ++i;
@@ -481,6 +491,12 @@ pcl::ConvexHull<PointInT>::reconstruct (PointCloud &points, std::vector<pcl::Ver
 
   deinitCompute ();
 }
+//////////////////////////////////////////////////////////////////////////
+template <typename PointInT> void
+pcl::ConvexHull<PointInT>::getHullPointIndices (pcl::PointIndices &hull_point_indices) const
+{
+  hull_point_indices = hull_indices_;
+}
 
 #define PCL_INSTANTIATE_ConvexHull(T) template class PCL_EXPORTS pcl::ConvexHull<T>;