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40 
41 #pragma once
42 
43 #include <pcl/features/feature.h>
44 #include <pcl/common/intensity.h>
45 
46 namespace pcl
47 {
48   /** \brief IntensityGradientEstimation estimates the intensity gradient for a point cloud that contains position
49     * and intensity values.  The intensity gradient at a given point will be a vector orthogonal to the surface
50     * normal and pointing in the direction of the greatest increase in local intensity; the vector's magnitude
51     * indicates the rate of intensity change.
52     * \author Michael Dixon
53     * \ingroup features
54     */
55   template <typename PointInT, typename PointNT, typename PointOutT, typename IntensitySelectorT = pcl::common::IntensityFieldAccessor<PointInT> >
56   class IntensityGradientEstimation : public FeatureFromNormals<PointInT, PointNT, PointOutT>
57   {
58     public:
59       using Ptr = shared_ptr<IntensityGradientEstimation<PointInT, PointNT, PointOutT, IntensitySelectorT> >;
60       using ConstPtr = shared_ptr<const IntensityGradientEstimation<PointInT, PointNT, PointOutT, IntensitySelectorT> >;
61       using Feature<PointInT, PointOutT>::feature_name_;
62       using Feature<PointInT, PointOutT>::getClassName;
63       using Feature<PointInT, PointOutT>::indices_;
64       using Feature<PointInT, PointOutT>::surface_;
65       using Feature<PointInT, PointOutT>::k_;
66       using Feature<PointInT, PointOutT>::search_parameter_;
67       using FeatureFromNormals<PointInT, PointNT, PointOutT>::normals_;
68 
69       using PointCloudOut = typename Feature<PointInT, PointOutT>::PointCloudOut;
70 
71       /** \brief Empty constructor. */
IntensityGradientEstimation()72       IntensityGradientEstimation () : intensity_ (), threads_ (0)
73       {
74         feature_name_ = "IntensityGradientEstimation";
75       };
76 
77       /** \brief Initialize the scheduler and set the number of threads to use.
78         * \param nr_threads the number of hardware threads to use (0 sets the value back to automatic)
79         */
80       inline void
81       setNumberOfThreads (unsigned int nr_threads = 0) { threads_ = nr_threads; }
82 
83     protected:
84       /** \brief Estimate the intensity gradients for a set of points given in <setInputCloud (), setIndices ()> using
85         *  the surface in setSearchSurface () and the spatial locator in setSearchMethod ().
86         *  \param output the resultant point cloud that contains the intensity gradient vectors
87         */
88       void
89       computeFeature (PointCloudOut &output) override;
90 
91       /** \brief Estimate the intensity gradient around a given point based on its spatial neighborhood of points
92         * \param cloud a point cloud dataset containing XYZI coordinates (Cartesian coordinates + intensity)
93         * \param indices the indices of the neighoring points in the dataset
94         * \param point the 3D Cartesian coordinates of the point at which to estimate the gradient
95         * \param mean_intensity
96         * \param normal the 3D surface normal of the given point
97         * \param gradient the resultant 3D gradient vector
98         */
99       void
100       computePointIntensityGradient (const pcl::PointCloud<PointInT> &cloud,
101                                      const pcl::Indices &indices,
102                                      const Eigen::Vector3f &point,
103                                      float mean_intensity,
104                                      const Eigen::Vector3f &normal,
105                                      Eigen::Vector3f &gradient);
106 
107     protected:
108       ///intensity field accessor structure
109       IntensitySelectorT intensity_;
110       ///number of threads to be used, default 0 (auto)
111       unsigned int threads_;
112   };
113 }
114 
115 #ifdef PCL_NO_PRECOMPILE
116 #include <pcl/features/impl/intensity_gradient.hpp>
117 #endif
118