Point Cloud Library (PCL) 1.13.1
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lccp_segmentation.hpp
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37
38#ifndef PCL_SEGMENTATION_IMPL_LCCP_SEGMENTATION_HPP_
39#define PCL_SEGMENTATION_IMPL_LCCP_SEGMENTATION_HPP_
40
41#include <pcl/segmentation/lccp_segmentation.h>
42#include <pcl/common/common.h>
43
44
45//////////////////////////////////////////////////////////
46//////////////////////////////////////////////////////////
47/////////////////// Public Functions /////////////////////
48//////////////////////////////////////////////////////////
49//////////////////////////////////////////////////////////
50
51
52
53template <typename PointT>
55 concavity_tolerance_threshold_ (10),
56 grouping_data_valid_ (false),
57 supervoxels_set_ (false),
58 use_smoothness_check_ (false),
59 smoothness_threshold_ (0.1),
60 use_sanity_check_ (false),
61 seed_resolution_ (0),
62 voxel_resolution_ (0),
63 k_factor_ (0),
64 min_segment_size_ (0)
65{
66}
67
68template <typename PointT>
70
71template <typename PointT> void
73{
74 sv_adjacency_list_.clear ();
75 processed_.clear ();
76 sv_label_to_supervoxel_map_.clear ();
77 sv_label_to_seg_label_map_.clear ();
78 seg_label_to_sv_list_map_.clear ();
79 seg_label_to_neighbor_set_map_.clear ();
80 grouping_data_valid_ = false;
81 supervoxels_set_ = false;
82}
83
84template <typename PointT> void
86{
87 if (supervoxels_set_)
88 {
89 // Calculate for every Edge if the connection is convex or invalid
90 // This effectively performs the segmentation.
91 calculateConvexConnections (sv_adjacency_list_);
92
93 // Correct edge relations using extended convexity definition if k>0
94 applyKconvexity (k_factor_);
95
96 // group supervoxels
97 doGrouping ();
98
99 grouping_data_valid_ = true;
100
101 // merge small segments
102 mergeSmallSegments ();
103 }
104 else
105 PCL_WARN ("[pcl::LCCPSegmentation::segment] WARNING: Call function setInputSupervoxels first. Nothing has been done. \n");
106}
107
108
109template <typename PointT> void
111{
112 if (grouping_data_valid_)
113 {
114 // Relabel all Points in cloud with new labels
115 for (auto &voxel : labeled_cloud_arg)
116 {
117 voxel.label = sv_label_to_seg_label_map_[voxel.label];
118 }
119 }
120 else
121 {
122 PCL_WARN ("[pcl::LCCPSegmentation::relabelCloud] WARNING: Call function segment first. Nothing has been done. \n");
123 }
124}
125
126
127
128//////////////////////////////////////////////////////////
129//////////////////////////////////////////////////////////
130/////////////////// Protected Functions //////////////////
131//////////////////////////////////////////////////////////
132//////////////////////////////////////////////////////////
133
134template <typename PointT> void
136{
137 seg_label_to_neighbor_set_map_.clear ();
138
139 std::uint32_t current_segLabel;
140 std::uint32_t neigh_segLabel;
141
142 VertexIterator sv_itr, sv_itr_end;
143 //The vertices in the supervoxel adjacency list are the supervoxel centroids
144 // For every Supervoxel..
145 for(std::tie(sv_itr, sv_itr_end) = boost::vertices(sv_adjacency_list_); sv_itr != sv_itr_end; ++sv_itr) // For all supervoxels
146 {
147 const std::uint32_t& sv_label = sv_adjacency_list_[*sv_itr];
148 current_segLabel = sv_label_to_seg_label_map_[sv_label];
149
150 AdjacencyIterator itr_neighbor, itr_neighbor_end;
151 // ..look at all neighbors and insert their labels into the neighbor set
152 for (std::tie(itr_neighbor, itr_neighbor_end) = boost::adjacent_vertices (*sv_itr, sv_adjacency_list_); itr_neighbor != itr_neighbor_end; ++itr_neighbor)
153 {
154 const std::uint32_t& neigh_label = sv_adjacency_list_[*itr_neighbor];
155 neigh_segLabel = sv_label_to_seg_label_map_[neigh_label];
156
157 if (current_segLabel != neigh_segLabel)
158 {
159 seg_label_to_neighbor_set_map_[current_segLabel].insert (neigh_segLabel);
160 }
161 }
162 }
163}
164
165template <typename PointT> void
167{
168 if (min_segment_size_ == 0)
169 return;
170
171 computeSegmentAdjacency ();
172
173 std::set<std::uint32_t> filteredSegLabels;
174
175 bool continue_filtering = true;
176
177 while (continue_filtering)
178 {
179 continue_filtering = false;
180
181 VertexIterator sv_itr, sv_itr_end;
182 // Iterate through all supervoxels, check if they are in a "small" segment -> change label to largest neighborID
183 for (std::tie(sv_itr, sv_itr_end) = boost::vertices (sv_adjacency_list_); sv_itr != sv_itr_end; ++sv_itr) // For all supervoxels
184 {
185 const std::uint32_t& sv_label = sv_adjacency_list_[*sv_itr];
186 std::uint32_t current_seg_label = sv_label_to_seg_label_map_[sv_label];
187 std::uint32_t largest_neigh_seg_label = current_seg_label;
188 std::uint32_t largest_neigh_size = seg_label_to_sv_list_map_[current_seg_label].size ();
189
190 const std::uint32_t& nr_neighbors = seg_label_to_neighbor_set_map_[current_seg_label].size ();
191 if (nr_neighbors == 0)
192 continue;
193
194 if (seg_label_to_sv_list_map_[current_seg_label].size () <= min_segment_size_)
195 {
196 continue_filtering = true;
197
198 // Find largest neighbor
199 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)
200 {
201 if (seg_label_to_sv_list_map_[*neighbors_itr].size () >= largest_neigh_size)
202 {
203 largest_neigh_seg_label = *neighbors_itr;
204 largest_neigh_size = seg_label_to_sv_list_map_[*neighbors_itr].size ();
205 }
206 }
207
208 // Add to largest neighbor
209 if (largest_neigh_seg_label != current_seg_label)
210 {
211 if (filteredSegLabels.count (largest_neigh_seg_label) > 0)
212 continue; // If neighbor was already assigned to someone else
213
214 sv_label_to_seg_label_map_[sv_label] = largest_neigh_seg_label;
215 filteredSegLabels.insert (current_seg_label);
216
217 // Assign supervoxel labels of filtered segment to new owner
218 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)
219 {
220 seg_label_to_sv_list_map_[largest_neigh_seg_label].insert (*sv_ID_itr);
221 }
222 }
223 }
224 }
225
226 // Erase filtered Segments from segment map
227 for (const unsigned int &filteredSegLabel : filteredSegLabels)
228 {
229 seg_label_to_sv_list_map_.erase (filteredSegLabel);
230 }
231
232 // After filtered Segments are deleted, compute completely new adjacency map
233 // NOTE Recomputing the adjacency of every segment in every iteration is an easy but inefficient solution.
234 // 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
235 computeSegmentAdjacency ();
236 } // End while (Filtering)
237}
238
239template <typename PointT> void
240pcl::LCCPSegmentation<PointT>::prepareSegmentation (const std::map<std::uint32_t, typename pcl::Supervoxel<PointT>::Ptr>& supervoxel_clusters_arg,
241 const std::multimap<std::uint32_t, std::uint32_t>& label_adjaceny_arg)
242{
243 // Clear internal data
244 reset ();
245
246 // Copy map with supervoxel pointers
247 sv_label_to_supervoxel_map_ = supervoxel_clusters_arg;
248
249 // Build a boost adjacency list from the adjacency multimap
250 std::map<std::uint32_t, VertexID> label_ID_map;
251
252 // Add all supervoxel labels as vertices
253 for (auto svlabel_itr = sv_label_to_supervoxel_map_.begin ();
254 svlabel_itr != sv_label_to_supervoxel_map_.end (); ++svlabel_itr)
255 {
256 const std::uint32_t& sv_label = svlabel_itr->first;
257 VertexID node_id = boost::add_vertex (sv_adjacency_list_);
258 sv_adjacency_list_[node_id] = sv_label;
259 label_ID_map[sv_label] = node_id;
260 }
261
262 // Add all edges
263 for (const auto &sv_neighbors_itr : label_adjaceny_arg)
264 {
265 const std::uint32_t& sv_label = sv_neighbors_itr.first;
266 const std::uint32_t& neighbor_label = sv_neighbors_itr.second;
267
268 VertexID u = label_ID_map[sv_label];
269 VertexID v = label_ID_map[neighbor_label];
270
271 boost::add_edge (u, v, sv_adjacency_list_);
272 }
273
274 // Initialization
275 // clear the processed_ map
276 seg_label_to_sv_list_map_.clear ();
277 for (auto svlabel_itr = sv_label_to_supervoxel_map_.begin ();
278 svlabel_itr != sv_label_to_supervoxel_map_.end (); ++svlabel_itr)
279 {
280 const std::uint32_t& sv_label = svlabel_itr->first;
281 processed_[sv_label] = false;
282 sv_label_to_seg_label_map_[sv_label] = 0;
283 }
284}
285
286
287
288
289template <typename PointT> void
291{
292 // clear the processed_ map
293 seg_label_to_sv_list_map_.clear ();
294 for (auto svlabel_itr = sv_label_to_supervoxel_map_.begin ();
295 svlabel_itr != sv_label_to_supervoxel_map_.end (); ++svlabel_itr)
296 {
297 const std::uint32_t& sv_label = svlabel_itr->first;
298 processed_[sv_label] = false;
299 sv_label_to_seg_label_map_[sv_label] = 0;
300 }
301
302 VertexIterator sv_itr, sv_itr_end;
303 // Perform depth search on the graph and recursively group all supervoxels with convex connections
304 //The vertices in the supervoxel adjacency list are the supervoxel centroids
305 // Note: *sv_itr is of type " boost::graph_traits<VoxelAdjacencyList>::vertex_descriptor " which it nothing but a typedef of std::size_t..
306 unsigned int segment_label = 1; // This starts at 1, because 0 is reserved for errors
307 for (std::tie(sv_itr, sv_itr_end) = boost::vertices (sv_adjacency_list_); sv_itr != sv_itr_end; ++sv_itr) // For all supervoxels
308 {
309 const VertexID sv_vertex_id = *sv_itr;
310 const std::uint32_t& sv_label = sv_adjacency_list_[sv_vertex_id];
311 if (!processed_[sv_label])
312 {
313 // Add neighbors (and their neighbors etc.) to group if similarity constraint is met
314 recursiveSegmentGrowing (sv_vertex_id, segment_label);
315 ++segment_label; // After recursive grouping ended (no more neighbors to consider) -> go to next group
316 }
317 }
318}
319
320template <typename PointT> void
322 const unsigned int segment_label)
323{
324 const std::uint32_t& sv_label = sv_adjacency_list_[query_point_id];
325
326 processed_[sv_label] = true;
327
328 // The next two lines add the supervoxel to the segment
329 sv_label_to_seg_label_map_[sv_label] = segment_label;
330 seg_label_to_sv_list_map_[segment_label].insert (sv_label);
331
332 OutEdgeIterator out_Edge_itr, out_Edge_itr_end;
333 // Iterate through all neighbors of this supervoxel and check whether they should be merged with the current supervoxel
334 // boost::out_edges (query_point_id, sv_adjacency_list_): adjacent vertices to node (*itr) in graph sv_adjacency_list_
335 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)
336 {
337 const VertexID neighbor_ID = boost::target (*out_Edge_itr, sv_adjacency_list_);
338 const std::uint32_t& neighbor_label = sv_adjacency_list_[neighbor_ID];
339
340 if (!processed_[neighbor_label]) // If neighbor was not already processed
341 {
342 if (sv_adjacency_list_[*out_Edge_itr].is_valid)
343 {
344 recursiveSegmentGrowing (neighbor_ID, segment_label);
345 }
346 }
347 } // End neighbor loop
348}
349
350template <typename PointT> void
352{
353 if (k_arg == 0)
354 return;
355
356 EdgeIterator edge_itr, edge_itr_end, next_edge;
357 // Check all edges in the graph for k-convexity
358 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)
359 {
360 ++next_edge; // next_edge iterator is necessary, because removing an edge invalidates the iterator to the current edge
361
362 bool is_convex = sv_adjacency_list_[*edge_itr].is_convex;
363
364 if (is_convex) // If edge is (0-)convex
365 {
366 unsigned int kcount = 0;
367
368 const VertexID source = boost::source (*edge_itr, sv_adjacency_list_);
369 const VertexID target = boost::target (*edge_itr, sv_adjacency_list_);
370
371 OutEdgeIterator source_neighbors_itr, source_neighbors_itr_end;
372 // Find common neighbors, check their connection
373 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
374 {
375 VertexID source_neighbor_ID = boost::target (*source_neighbors_itr, sv_adjacency_list_);
376
377 OutEdgeIterator target_neighbors_itr, target_neighbors_itr_end;
378 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
379 {
380 VertexID target_neighbor_ID = boost::target (*target_neighbors_itr, sv_adjacency_list_);
381 if (source_neighbor_ID == target_neighbor_ID) // Common neighbor
382 {
383 EdgeID src_edge = boost::edge (source, source_neighbor_ID, sv_adjacency_list_).first;
384 EdgeID tar_edge = boost::edge (target, source_neighbor_ID, sv_adjacency_list_).first;
385
386 bool src_is_convex = (sv_adjacency_list_)[src_edge].is_convex;
387 bool tar_is_convex = (sv_adjacency_list_)[tar_edge].is_convex;
388
389 if (src_is_convex && tar_is_convex)
390 ++kcount;
391
392 break;
393 }
394 }
395
396 if (kcount >= k_arg) // Connection is k-convex, stop search
397 break;
398 }
399
400 // Check k convexity
401 if (kcount < k_arg)
402 (sv_adjacency_list_)[*edge_itr].is_valid = false;
403 }
404 }
405}
406
407template <typename PointT> void
409{
410
411 EdgeIterator edge_itr, edge_itr_end, next_edge;
412 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)
413 {
414 ++next_edge; // next_edge iterator is necessary, because removing an edge invalidates the iterator to the current edge
415
416 std::uint32_t source_sv_label = adjacency_list_arg[boost::source (*edge_itr, adjacency_list_arg)];
417 std::uint32_t target_sv_label = adjacency_list_arg[boost::target (*edge_itr, adjacency_list_arg)];
418
419 float normal_difference;
420 bool is_convex = connIsConvex (source_sv_label, target_sv_label, normal_difference);
421 adjacency_list_arg[*edge_itr].is_convex = is_convex;
422 adjacency_list_arg[*edge_itr].is_valid = is_convex;
423 adjacency_list_arg[*edge_itr].normal_difference = normal_difference;
424 }
425}
426
427template <typename PointT> bool
428pcl::LCCPSegmentation<PointT>::connIsConvex (const std::uint32_t source_label_arg,
429 const std::uint32_t target_label_arg,
430 float &normal_angle)
431{
432 typename pcl::Supervoxel<PointT>::Ptr& sv_source = sv_label_to_supervoxel_map_[source_label_arg];
433 typename pcl::Supervoxel<PointT>::Ptr& sv_target = sv_label_to_supervoxel_map_[target_label_arg];
434
435 const Eigen::Vector3f& source_centroid = sv_source->centroid_.getVector3fMap ();
436 const Eigen::Vector3f& target_centroid = sv_target->centroid_.getVector3fMap ();
437
438 const Eigen::Vector3f& source_normal = sv_source->normal_.getNormalVector3fMap (). normalized ();
439 const Eigen::Vector3f& target_normal = sv_target->normal_.getNormalVector3fMap (). normalized ();
440
441 //NOTE For angles below 0 nothing will be merged
442 if (concavity_tolerance_threshold_ < 0)
443 {
444 return (false);
445 }
446
447 bool is_convex = true;
448 bool is_smooth = true;
449
450 normal_angle = getAngle3D (source_normal, target_normal, true);
451 // Geometric comparisons
452 Eigen::Vector3f vec_t_to_s, vec_s_to_t;
453
454 vec_t_to_s = source_centroid - target_centroid;
455 vec_s_to_t = -vec_t_to_s;
456
457 Eigen::Vector3f ncross;
458 ncross = source_normal.cross (target_normal);
459
460 // Smoothness Check: Check if there is a step between adjacent patches
461 if (use_smoothness_check_)
462 {
463 float expected_distance = ncross.norm () * seed_resolution_;
464 float dot_p_1 = vec_t_to_s.dot (source_normal);
465 float dot_p_2 = vec_s_to_t.dot (target_normal);
466 float point_dist = (std::fabs (dot_p_1) < std::fabs (dot_p_2)) ? std::fabs (dot_p_1) : std::fabs (dot_p_2);
467 const float dist_smoothing = smoothness_threshold_ * voxel_resolution_; // This is a slacking variable especially important for patches with very similar normals
468
469 if (point_dist > (expected_distance + dist_smoothing))
470 {
471 is_smooth &= false;
472 }
473 }
474 // ----------------
475
476 // Sanity Criterion: Check if definition convexity/concavity makes sense for connection of given patches
477 float intersection_angle = getAngle3D (ncross, vec_t_to_s, true);
478 float min_intersect_angle = (intersection_angle < 90.) ? intersection_angle : 180. - intersection_angle;
479
480 float intersect_thresh = 60. * 1. / (1. + std::exp (-0.25 * (normal_angle - 25.)));
481 if (min_intersect_angle < intersect_thresh && use_sanity_check_)
482 {
483 // std::cout << "Concave/Convex not defined for given case!" << std::endl;
484 is_convex &= false;
485 }
486
487
488 // vec_t_to_s is the reference direction for angle measurements
489 // Convexity Criterion: Check if connection of patches is convex. If this is the case the two supervoxels should be merged.
490 if ((getAngle3D (vec_t_to_s, source_normal) - getAngle3D (vec_t_to_s, target_normal)) <= 0)
491 {
492 is_convex &= true; // connection convex
493 }
494 else
495 {
496 is_convex &= (normal_angle < concavity_tolerance_threshold_); // concave connections will be accepted if difference of normals is small
497 }
498 return (is_convex && is_smooth);
499}
500
501#endif // PCL_SEGMENTATION_IMPL_LCCP_SEGMENTATION_HPP_
virtual ~LCCPSegmentation()
typename boost::graph_traits< SupervoxelAdjacencyList >::vertex_iterator VertexIterator
typename boost::graph_traits< SupervoxelAdjacencyList >::edge_iterator EdgeIterator
boost::adjacency_list< boost::setS, boost::setS, boost::undirectedS, std::uint32_t, EdgeProperties > SupervoxelAdjacencyList
void recursiveSegmentGrowing(const VertexID &queryPointID, const unsigned int group_label)
Assigns neighbors of the query point to the same group as the query point.
void calculateConvexConnections(SupervoxelAdjacencyList &adjacency_list_arg)
Calculates convexity of edges and saves this to the adjacency graph.
void computeSegmentAdjacency()
Compute the adjacency of the segments.
void relabelCloud(pcl::PointCloud< pcl::PointXYZL > &labeled_cloud_arg)
Relabels cloud with supervoxel labels with the computed segment labels.
void mergeSmallSegments()
Segments smaller than min_segment_size_ are merged to the label of largest neighbor.
void 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_adjacency_arg)
Is called within setInputSupervoxels mainly to reserve required memory.
void segment()
Merge supervoxels using local convexity.
typename boost::graph_traits< SupervoxelAdjacencyList >::out_edge_iterator OutEdgeIterator
typename boost::graph_traits< SupervoxelAdjacencyList >::adjacency_iterator AdjacencyIterator
bool connIsConvex(const std::uint32_t source_label_arg, const std::uint32_t target_label_arg, float &normal_angle)
Returns true if the connection between source and target is convex.
void doGrouping()
Perform depth search on the graph and recursively group all supervoxels with convex connections.
void applyKconvexity(const unsigned int k_arg)
Connections are only convex if this is true for at least k_arg common neighbors of the two patches.
typename boost::graph_traits< SupervoxelAdjacencyList >::edge_descriptor EdgeID
typename boost::graph_traits< SupervoxelAdjacencyList >::vertex_descriptor VertexID
void reset()
Reset internal memory.
PointCloud represents the base class in PCL for storing collections of 3D points.
pcl::PointXYZRGBA centroid_
The centroid of the supervoxel - average voxel.
shared_ptr< Supervoxel< PointT > > Ptr
pcl::Normal normal_
The normal calculated for the voxels contained in the supervoxel.
Define standard C methods and C++ classes that are common to all methods.
double getAngle3D(const Eigen::Vector4f &v1, const Eigen::Vector4f &v2, const bool in_degree=false)
Compute the smallest angle between two 3D vectors in radians (default) or degree.
Definition common.hpp:47