1 /*
2  * Software License Agreement (BSD License)
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4  *  Point Cloud Library (PCL) - www.pointclouds.org
5  *  Copyright (c) 2011, Alexandru-Eugen Ichim
6  *  Copyright (c) 2012-, Open Perception, Inc.
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39 
40 #pragma once
41 
42 #include <pcl/pcl_base.h>
43 #include <pcl/features/feature.h>
44 #include <pcl/point_representation.h>
45 #include <pcl/common/norms.h>
46 #include <list>
47 
48 namespace pcl
49 {
50   /** \brief Generic class for extracting the persistent features from an input point cloud
51    * It can be given any Feature estimator instance and will compute the features of the input
52    * over a multiscale representation of the cloud and output the unique ones over those scales.
53    *
54    * Please refer to the following publication for more details:
55    *    Radu Bogdan Rusu, Zoltan Csaba Marton, Nico Blodow, and Michael Beetz
56    *    Persistent Point Feature Histograms for 3D Point Clouds
57    *    Proceedings of the 10th International Conference on Intelligent Autonomous Systems (IAS-10)
58    *    2008, Baden-Baden, Germany
59    *
60    * \author Alexandru-Eugen Ichim
61    */
62   template <typename PointSource, typename PointFeature>
63   class MultiscaleFeaturePersistence : public PCLBase<PointSource>
64   {
65     public:
66       using Ptr = shared_ptr<MultiscaleFeaturePersistence<PointSource, PointFeature> >;
67       using ConstPtr = shared_ptr<const MultiscaleFeaturePersistence<PointSource, PointFeature> >;
68       using FeatureCloud = pcl::PointCloud<PointFeature>;
69       using FeatureCloudPtr = typename pcl::PointCloud<PointFeature>::Ptr;
70       using FeatureEstimatorPtr = typename pcl::Feature<PointSource, PointFeature>::Ptr;
71       using FeatureRepresentationConstPtr = typename pcl::PointRepresentation<PointFeature>::ConstPtr;
72 
73       using pcl::PCLBase<PointSource>::input_;
74 
75       /** \brief Empty constructor */
76       MultiscaleFeaturePersistence ();
77 
78       /** \brief Empty destructor */
~MultiscaleFeaturePersistence()79       ~MultiscaleFeaturePersistence () {}
80 
81       /** \brief Method that calls computeFeatureAtScale () for each scale parameter */
82       void
83       computeFeaturesAtAllScales ();
84 
85       /** \brief Central function that computes the persistent features
86        * \param output_features a cloud containing the persistent features
87        * \param output_indices vector containing the indices of the points in the input cloud
88        * that have persistent features, under a one-to-one correspondence with the output_features cloud
89        */
90       void
91       determinePersistentFeatures (FeatureCloud &output_features,
92                                    pcl::IndicesPtr &output_indices);
93 
94       /** \brief Method for setting the scale parameters for the algorithm
95        * \param scale_values vector of scales to determine the characteristic of each scaling step
96        */
97       inline void
setScalesVector(std::vector<float> & scale_values)98       setScalesVector (std::vector<float> &scale_values) { scale_values_ = scale_values; }
99 
100       /** \brief Method for getting the scale parameters vector */
101       inline std::vector<float>
getScalesVector()102       getScalesVector () { return scale_values_; }
103 
104       /** \brief Setter method for the feature estimator
105        * \param feature_estimator pointer to the feature estimator instance that will be used
106        * \note the feature estimator instance should already have the input data given beforehand
107        * and everything set, ready to be given the compute () command
108        */
109       inline void
setFeatureEstimator(FeatureEstimatorPtr feature_estimator)110       setFeatureEstimator (FeatureEstimatorPtr feature_estimator) { feature_estimator_ = feature_estimator; };
111 
112       /** \brief Getter method for the feature estimator */
113       inline FeatureEstimatorPtr
getFeatureEstimator()114       getFeatureEstimator () { return feature_estimator_; }
115 
116       /** \brief Provide a pointer to the feature representation to use to convert features to k-D vectors.
117        * \param feature_representation the const boost shared pointer to a PointRepresentation
118        */
119       inline void
setPointRepresentation(const FeatureRepresentationConstPtr & feature_representation)120       setPointRepresentation (const FeatureRepresentationConstPtr& feature_representation) { feature_representation_ = feature_representation; }
121 
122       /** \brief Get a pointer to the feature representation used when converting features into k-D vectors. */
123       inline FeatureRepresentationConstPtr const
getPointRepresentation()124       getPointRepresentation () { return feature_representation_; }
125 
126       /** \brief Sets the alpha parameter
127        * \param alpha value to replace the current alpha with
128        */
129       inline void
setAlpha(float alpha)130       setAlpha (float alpha) { alpha_ = alpha; }
131 
132       /** \brief Get the value of the alpha parameter */
133       inline float
getAlpha()134       getAlpha () { return alpha_; }
135 
136       /** \brief Method for setting the distance metric that will be used for computing the difference between feature vectors
137        * \param distance_metric the new distance metric chosen from the NormType enum
138        */
139       inline void
setDistanceMetric(NormType distance_metric)140       setDistanceMetric (NormType distance_metric) { distance_metric_ = distance_metric; }
141 
142       /** \brief Returns the distance metric that is currently used to calculate the difference between feature vectors */
143       inline NormType
getDistanceMetric()144       getDistanceMetric () { return distance_metric_; }
145 
146 
147     private:
148       /** \brief Checks if all the necessary input was given and the computations can successfully start */
149       bool
150       initCompute ();
151 
152 
153       /** \brief Method to compute the features for the point cloud at the given scale */
154       virtual void
155       computeFeatureAtScale (float &scale,
156                              FeatureCloudPtr &features);
157 
158 
159       /** \brief Function that calculates the scalar difference between two features
160        * \return the difference as a floating point type
161        */
162       float
163       distanceBetweenFeatures (const std::vector<float> &a,
164                                const std::vector<float> &b);
165 
166       /** \brief Method that averages all the features at all scales in order to obtain the global mean feature;
167        * this value is stored in the mean_feature field
168        */
169       void
170       calculateMeanFeature ();
171 
172       /** \brief Selects the so-called 'unique' features from the cloud of features at each level.
173        * These features are the ones that fall outside the standard deviation * alpha_
174        */
175       void
176       extractUniqueFeatures ();
177 
178 
179       /** \brief The general parameter for determining each scale level */
180       std::vector<float> scale_values_;
181 
182       /** \brief Parameter that determines if a feature is to be considered unique or not */
183       float alpha_;
184 
185       /** \brief Parameter that determines which distance metric is to be usedto calculate the difference between feature vectors */
186       NormType distance_metric_;
187 
188       /** \brief the feature estimator that will be used to determine the feature set at each scale level */
189       FeatureEstimatorPtr feature_estimator_;
190 
191       std::vector<FeatureCloudPtr> features_at_scale_;
192       std::vector<std::vector<std::vector<float> > > features_at_scale_vectorized_;
193       std::vector<float> mean_feature_;
194       FeatureRepresentationConstPtr feature_representation_;
195 
196       /** \brief Two structures in which to hold the results of the unique feature extraction process.
197        * They are superfluous with respect to each other, but improve the time performance of the algorithm
198        */
199       std::vector<std::list<std::size_t> > unique_features_indices_;
200       std::vector<std::vector<bool> > unique_features_table_;
201   };
202 }
203 
204 #ifdef PCL_NO_PRECOMPILE
205 #include <pcl/features/impl/multiscale_feature_persistence.hpp>
206 #endif
207