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#ifndef PCL_SEGMENTATION_IMPL_LCCP_SEGMENTATION_HPP_
#define PCL_SEGMENTATION_IMPL_LCCP_SEGMENTATION_HPP_
#include <pcl/segmentation/lccp_segmentation.h>
#include <pcl/common/common.h>
//////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////
/////////////////// Public Functions /////////////////////
//////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////
template <typename PointT>
pcl::LCCPSegmentation<PointT>::LCCPSegmentation () :
concavity_tolerance_threshold_ (10),
grouping_data_valid_ (false),
supervoxels_set_ (false),
use_smoothness_check_ (false),
smoothness_threshold_ (0.1),
use_sanity_check_ (false),
seed_resolution_ (0),
voxel_resolution_ (0),
k_factor_ (0),
min_segment_size_ (0)
{
}
template <typename PointT>
pcl::LCCPSegmentation<PointT>::~LCCPSegmentation ()
{
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::reset ()
{
sv_adjacency_list_.clear ();
processed_.clear ();
sv_label_to_supervoxel_map_.clear ();
sv_label_to_seg_label_map_.clear ();
seg_label_to_sv_list_map_.clear ();
seg_label_to_neighbor_set_map_.clear ();
grouping_data_valid_ = false;
supervoxels_set_ = false;
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::segment ()
{
if (supervoxels_set_)
{
// Calculate for every Edge if the connection is convex or invalid
// This effectively performs the segmentation.
calculateConvexConnections (sv_adjacency_list_);
// Correct edge relations using extended convexity definition if k>0
applyKconvexity (k_factor_);
// group supervoxels
doGrouping ();
grouping_data_valid_ = true;
// merge small segments
mergeSmallSegments ();
}
else
PCL_WARN ("[pcl::LCCPSegmentation::segment] WARNING: Call function setInputSupervoxels first. Nothing has been done. \n");
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::relabelCloud (pcl::PointCloud<pcl::PointXYZL> &labeled_cloud_arg)
{
if (grouping_data_valid_)
{
// Relabel all Points in cloud with new labels
for (auto &voxel : labeled_cloud_arg)
{
voxel.label = sv_label_to_seg_label_map_[voxel.label];
}
}
else
{
PCL_WARN ("[pcl::LCCPSegmentation::relabelCloud] WARNING: Call function segment first. Nothing has been done. \n");
}
}
//////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////
/////////////////// Protected Functions //////////////////
//////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::computeSegmentAdjacency ()
{
seg_label_to_neighbor_set_map_.clear ();
std::uint32_t current_segLabel;
std::uint32_t neigh_segLabel;
VertexIterator sv_itr, sv_itr_end;
//The vertices in the supervoxel adjacency list are the supervoxel centroids
// For every Supervoxel..
for(std::tie(sv_itr, sv_itr_end) = boost::vertices(sv_adjacency_list_); sv_itr != sv_itr_end; ++sv_itr) // For all supervoxels
{
const std::uint32_t& sv_label = sv_adjacency_list_[*sv_itr];
current_segLabel = sv_label_to_seg_label_map_[sv_label];
AdjacencyIterator itr_neighbor, itr_neighbor_end;
// ..look at all neighbors and insert their labels into the neighbor set
for (std::tie(itr_neighbor, itr_neighbor_end) = boost::adjacent_vertices (*sv_itr, sv_adjacency_list_); itr_neighbor != itr_neighbor_end; ++itr_neighbor)
{
const std::uint32_t& neigh_label = sv_adjacency_list_[*itr_neighbor];
neigh_segLabel = sv_label_to_seg_label_map_[neigh_label];
if (current_segLabel != neigh_segLabel)
{
seg_label_to_neighbor_set_map_[current_segLabel].insert (neigh_segLabel);
}
}
}
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::mergeSmallSegments ()
{
if (min_segment_size_ == 0)
return;
computeSegmentAdjacency ();
std::set<std::uint32_t> filteredSegLabels;
bool continue_filtering = true;
while (continue_filtering)
{
continue_filtering = false;
unsigned int nr_filtered = 0;
VertexIterator sv_itr, sv_itr_end;
// Iterate through all supervoxels, check if they are in a "small" segment -> change label to largest neighborID
for (std::tie(sv_itr, sv_itr_end) = boost::vertices (sv_adjacency_list_); sv_itr != sv_itr_end; ++sv_itr) // For all supervoxels
{
const std::uint32_t& sv_label = sv_adjacency_list_[*sv_itr];
std::uint32_t current_seg_label = sv_label_to_seg_label_map_[sv_label];
std::uint32_t largest_neigh_seg_label = current_seg_label;
std::uint32_t largest_neigh_size = seg_label_to_sv_list_map_[current_seg_label].size ();
const std::uint32_t& nr_neighbors = seg_label_to_neighbor_set_map_[current_seg_label].size ();
if (nr_neighbors == 0)
continue;
if (seg_label_to_sv_list_map_[current_seg_label].size () <= min_segment_size_)
{
continue_filtering = true;
nr_filtered++;
// Find largest neighbor
for (auto neighbors_itr = seg_label_to_neighbor_set_map_[current_seg_label].cbegin (); neighbors_itr != seg_label_to_neighbor_set_map_[current_seg_label].cend (); ++neighbors_itr)
{
if (seg_label_to_sv_list_map_[*neighbors_itr].size () >= largest_neigh_size)
{
largest_neigh_seg_label = *neighbors_itr;
largest_neigh_size = seg_label_to_sv_list_map_[*neighbors_itr].size ();
}
}
// Add to largest neighbor
if (largest_neigh_seg_label != current_seg_label)
{
if (filteredSegLabels.count (largest_neigh_seg_label) > 0)
continue; // If neighbor was already assigned to someone else
sv_label_to_seg_label_map_[sv_label] = largest_neigh_seg_label;
filteredSegLabels.insert (current_seg_label);
// Assign supervoxel labels of filtered segment to new owner
for (auto sv_ID_itr = seg_label_to_sv_list_map_[current_seg_label].cbegin (); sv_ID_itr != seg_label_to_sv_list_map_[current_seg_label].cend (); ++sv_ID_itr)
{
seg_label_to_sv_list_map_[largest_neigh_seg_label].insert (*sv_ID_itr);
}
}
}
}
// Erase filtered Segments from segment map
for (const unsigned int &filteredSegLabel : filteredSegLabels)
{
seg_label_to_sv_list_map_.erase (filteredSegLabel);
}
// After filtered Segments are deleted, compute completely new adjacency map
// NOTE Recomputing the adjacency of every segment in every iteration is an easy but inefficient solution.
// Because the number of segments in an average scene is usually well below 1000, the time spend for noise filtering is still negligible in most cases
computeSegmentAdjacency ();
} // End while (Filtering)
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::prepareSegmentation (const std::map<std::uint32_t, typename pcl::Supervoxel<PointT>::Ptr>& supervoxel_clusters_arg,
const std::multimap<std::uint32_t, std::uint32_t>& label_adjaceny_arg)
{
// Clear internal data
reset ();
// Copy map with supervoxel pointers
sv_label_to_supervoxel_map_ = supervoxel_clusters_arg;
// Build a boost adjacency list from the adjacency multimap
std::map<std::uint32_t, VertexID> label_ID_map;
// Add all supervoxel labels as vertices
for (typename std::map<std::uint32_t, typename pcl::Supervoxel<PointT>::Ptr>::iterator svlabel_itr = sv_label_to_supervoxel_map_.begin ();
svlabel_itr != sv_label_to_supervoxel_map_.end (); ++svlabel_itr)
{
const std::uint32_t& sv_label = svlabel_itr->first;
VertexID node_id = boost::add_vertex (sv_adjacency_list_);
sv_adjacency_list_[node_id] = sv_label;
label_ID_map[sv_label] = node_id;
}
// Add all edges
for (const auto &sv_neighbors_itr : label_adjaceny_arg)
{
const std::uint32_t& sv_label = sv_neighbors_itr.first;
const std::uint32_t& neighbor_label = sv_neighbors_itr.second;
VertexID u = label_ID_map[sv_label];
VertexID v = label_ID_map[neighbor_label];
boost::add_edge (u, v, sv_adjacency_list_);
}
// Initialization
// clear the processed_ map
seg_label_to_sv_list_map_.clear ();
for (typename std::map<std::uint32_t, typename pcl::Supervoxel<PointT>::Ptr>::iterator svlabel_itr = sv_label_to_supervoxel_map_.begin ();
svlabel_itr != sv_label_to_supervoxel_map_.end (); ++svlabel_itr)
{
const std::uint32_t& sv_label = svlabel_itr->first;
processed_[sv_label] = false;
sv_label_to_seg_label_map_[sv_label] = 0;
}
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::doGrouping ()
{
// clear the processed_ map
seg_label_to_sv_list_map_.clear ();
for (typename std::map<std::uint32_t, typename pcl::Supervoxel<PointT>::Ptr>::iterator svlabel_itr = sv_label_to_supervoxel_map_.begin ();
svlabel_itr != sv_label_to_supervoxel_map_.end (); ++svlabel_itr)
{
const std::uint32_t& sv_label = svlabel_itr->first;
processed_[sv_label] = false;
sv_label_to_seg_label_map_[sv_label] = 0;
}
VertexIterator sv_itr, sv_itr_end;
// Perform depth search on the graph and recursively group all supervoxels with convex connections
//The vertices in the supervoxel adjacency list are the supervoxel centroids
// Note: *sv_itr is of type " boost::graph_traits<VoxelAdjacencyList>::vertex_descriptor " which it nothing but a typedef of std::size_t..
unsigned int segment_label = 1; // This starts at 1, because 0 is reserved for errors
for (std::tie(sv_itr, sv_itr_end) = boost::vertices (sv_adjacency_list_); sv_itr != sv_itr_end; ++sv_itr) // For all supervoxels
{
const VertexID sv_vertex_id = *sv_itr;
const std::uint32_t& sv_label = sv_adjacency_list_[sv_vertex_id];
if (!processed_[sv_label])
{
// Add neighbors (and their neighbors etc.) to group if similarity constraint is met
recursiveSegmentGrowing (sv_vertex_id, segment_label);
++segment_label; // After recursive grouping ended (no more neighbors to consider) -> go to next group
}
}
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::recursiveSegmentGrowing (const VertexID &query_point_id,
const unsigned int segment_label)
{
const std::uint32_t& sv_label = sv_adjacency_list_[query_point_id];
processed_[sv_label] = true;
// The next two lines add the supervoxel to the segment
sv_label_to_seg_label_map_[sv_label] = segment_label;
seg_label_to_sv_list_map_[segment_label].insert (sv_label);
OutEdgeIterator out_Edge_itr, out_Edge_itr_end;
// Iterate through all neighbors of this supervoxel and check whether they should be merged with the current supervoxel
// boost::out_edges (query_point_id, sv_adjacency_list_): adjacent vertices to node (*itr) in graph sv_adjacency_list_
for (std::tie(out_Edge_itr, out_Edge_itr_end) = boost::out_edges (query_point_id, sv_adjacency_list_); out_Edge_itr != out_Edge_itr_end; ++out_Edge_itr)
{
const VertexID neighbor_ID = boost::target (*out_Edge_itr, sv_adjacency_list_);
const std::uint32_t& neighbor_label = sv_adjacency_list_[neighbor_ID];
if (!processed_[neighbor_label]) // If neighbor was not already processed
{
if (sv_adjacency_list_[*out_Edge_itr].is_valid)
{
recursiveSegmentGrowing (neighbor_ID, segment_label);
}
}
} // End neighbor loop
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::applyKconvexity (const unsigned int k_arg)
{
if (k_arg == 0)
return;
EdgeIterator edge_itr, edge_itr_end, next_edge;
// Check all edges in the graph for k-convexity
for (std::tie (edge_itr, edge_itr_end) = boost::edges (sv_adjacency_list_), next_edge = edge_itr; edge_itr != edge_itr_end; edge_itr = next_edge)
{
++next_edge; // next_edge iterator is necessary, because removing an edge invalidates the iterator to the current edge
bool is_convex = sv_adjacency_list_[*edge_itr].is_convex;
if (is_convex) // If edge is (0-)convex
{
unsigned int kcount = 0;
const VertexID source = boost::source (*edge_itr, sv_adjacency_list_);
const VertexID target = boost::target (*edge_itr, sv_adjacency_list_);
OutEdgeIterator source_neighbors_itr, source_neighbors_itr_end;
// Find common neighbors, check their connection
for (std::tie(source_neighbors_itr, source_neighbors_itr_end) = boost::out_edges (source, sv_adjacency_list_); source_neighbors_itr != source_neighbors_itr_end; ++source_neighbors_itr) // For all supervoxels
{
VertexID source_neighbor_ID = boost::target (*source_neighbors_itr, sv_adjacency_list_);
OutEdgeIterator target_neighbors_itr, target_neighbors_itr_end;
for (std::tie(target_neighbors_itr, target_neighbors_itr_end) = boost::out_edges (target, sv_adjacency_list_); target_neighbors_itr != target_neighbors_itr_end; ++target_neighbors_itr) // For all supervoxels
{
VertexID target_neighbor_ID = boost::target (*target_neighbors_itr, sv_adjacency_list_);
if (source_neighbor_ID == target_neighbor_ID) // Common neighbor
{
EdgeID src_edge = boost::edge (source, source_neighbor_ID, sv_adjacency_list_).first;
EdgeID tar_edge = boost::edge (target, source_neighbor_ID, sv_adjacency_list_).first;
bool src_is_convex = (sv_adjacency_list_)[src_edge].is_convex;
bool tar_is_convex = (sv_adjacency_list_)[tar_edge].is_convex;
if (src_is_convex && tar_is_convex)
++kcount;
break;
}
}
if (kcount >= k_arg) // Connection is k-convex, stop search
break;
}
// Check k convexity
if (kcount < k_arg)
(sv_adjacency_list_)[*edge_itr].is_valid = false;
}
}
}
template <typename PointT> void
pcl::LCCPSegmentation<PointT>::calculateConvexConnections (SupervoxelAdjacencyList& adjacency_list_arg)
{
EdgeIterator edge_itr, edge_itr_end, next_edge;
for (std::tie(edge_itr, edge_itr_end) = boost::edges (adjacency_list_arg), next_edge = edge_itr; edge_itr != edge_itr_end; edge_itr = next_edge)
{
++next_edge; // next_edge iterator is necessary, because removing an edge invalidates the iterator to the current edge
std::uint32_t source_sv_label = adjacency_list_arg[boost::source (*edge_itr, adjacency_list_arg)];
std::uint32_t target_sv_label = adjacency_list_arg[boost::target (*edge_itr, adjacency_list_arg)];
float normal_difference;
bool is_convex = connIsConvex (source_sv_label, target_sv_label, normal_difference);
adjacency_list_arg[*edge_itr].is_convex = is_convex;
adjacency_list_arg[*edge_itr].is_valid = is_convex;
adjacency_list_arg[*edge_itr].normal_difference = normal_difference;
}
}
template <typename PointT> bool
pcl::LCCPSegmentation<PointT>::connIsConvex (const std::uint32_t source_label_arg,
const std::uint32_t target_label_arg,
float &normal_angle)
{
typename pcl::Supervoxel<PointT>::Ptr& sv_source = sv_label_to_supervoxel_map_[source_label_arg];
typename pcl::Supervoxel<PointT>::Ptr& sv_target = sv_label_to_supervoxel_map_[target_label_arg];
const Eigen::Vector3f& source_centroid = sv_source->centroid_.getVector3fMap ();
const Eigen::Vector3f& target_centroid = sv_target->centroid_.getVector3fMap ();
const Eigen::Vector3f& source_normal = sv_source->normal_.getNormalVector3fMap (). normalized ();
const Eigen::Vector3f& target_normal = sv_target->normal_.getNormalVector3fMap (). normalized ();
//NOTE For angles below 0 nothing will be merged
if (concavity_tolerance_threshold_ < 0)
{
return (false);
}
bool is_convex = true;
bool is_smooth = true;
normal_angle = getAngle3D (source_normal, target_normal, true);
// Geometric comparisons
Eigen::Vector3f vec_t_to_s, vec_s_to_t;
vec_t_to_s = source_centroid - target_centroid;
vec_s_to_t = -vec_t_to_s;
Eigen::Vector3f ncross;
ncross = source_normal.cross (target_normal);
// Smoothness Check: Check if there is a step between adjacent patches
if (use_smoothness_check_)
{
float expected_distance = ncross.norm () * seed_resolution_;
float dot_p_1 = vec_t_to_s.dot (source_normal);
float dot_p_2 = vec_s_to_t.dot (target_normal);
float point_dist = (std::fabs (dot_p_1) < std::fabs (dot_p_2)) ? std::fabs (dot_p_1) : std::fabs (dot_p_2);
const float dist_smoothing = smoothness_threshold_ * voxel_resolution_; // This is a slacking variable especially important for patches with very similar normals
if (point_dist > (expected_distance + dist_smoothing))
{
is_smooth &= false;
}
}
// ----------------
// Sanity Criterion: Check if definition convexity/concavity makes sense for connection of given patches
float intersection_angle = getAngle3D (ncross, vec_t_to_s, true);
float min_intersect_angle = (intersection_angle < 90.) ? intersection_angle : 180. - intersection_angle;
float intersect_thresh = 60. * 1. / (1. + std::exp (-0.25 * (normal_angle - 25.)));
if (min_intersect_angle < intersect_thresh && use_sanity_check_)
{
// std::cout << "Concave/Convex not defined for given case!" << std::endl;
is_convex &= false;
}
// vec_t_to_s is the reference direction for angle measurements
// Convexity Criterion: Check if connection of patches is convex. If this is the case the two supervoxels should be merged.
if ((getAngle3D (vec_t_to_s, source_normal) - getAngle3D (vec_t_to_s, target_normal)) <= 0)
{
is_convex &= true; // connection convex
}
else
{
is_convex &= (normal_angle < concavity_tolerance_threshold_); // concave connections will be accepted if difference of normals is small
}
return (is_convex && is_smooth);
}
#endif // PCL_SEGMENTATION_IMPL_LCCP_SEGMENTATION_HPP_