sift_keypoint.h

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#ifndef PCL_SIFT_KEYPOINT_H_
#define PCL_SIFT_KEYPOINT_H_

#include <pcl/keypoints/keypoint.h>

namespace pcl
{
  template<typename PointT>
  struct SIFTKeypointFieldSelector
  {
    inline float
    operator () (const PointT & p) const
    {
      return p.intensity;
    }
  };
  template<>
  struct SIFTKeypointFieldSelector<PointNormal>
  {
    inline float
    operator () (const PointNormal & p) const
    {
      return p.curvature;
    }
  };
  template<>
  struct SIFTKeypointFieldSelector<PointXYZRGB>
  {
    inline float
    operator () (const PointXYZRGB & p) const
    {
      return (static_cast<float> (299*p.r + 587*p.g + 114*p.b) / 1000.0f);
    }
  };
  template<>
  struct SIFTKeypointFieldSelector<PointXYZRGBA>
  {
    inline float
    operator () (const PointXYZRGBA & p) const
    {
      return (static_cast<float> (299*p.r + 587*p.g + 114*p.b) / 1000.0f);
    }
  };

  template <typename PointInT, typename PointOutT>
  class SIFTKeypoint : public Keypoint<PointInT, PointOutT>
  {
    public:
      typedef boost::shared_ptr<SIFTKeypoint<PointInT, PointOutT> > Ptr;
      typedef boost::shared_ptr<const SIFTKeypoint<PointInT, PointOutT> > ConstPtr;

      typedef typename Keypoint<PointInT, PointOutT>::PointCloudIn PointCloudIn;
      typedef typename Keypoint<PointInT, PointOutT>::PointCloudOut PointCloudOut;
      typedef typename Keypoint<PointInT, PointOutT>::KdTree KdTree;

      using Keypoint<PointInT, PointOutT>::name_;
      using Keypoint<PointInT, PointOutT>::input_;
      using Keypoint<PointInT, PointOutT>::indices_;
      using Keypoint<PointInT, PointOutT>::surface_;
      using Keypoint<PointInT, PointOutT>::tree_;
      using Keypoint<PointInT, PointOutT>::initCompute;    

      SIFTKeypoint () : min_scale_ (0.0), nr_octaves_ (0), nr_scales_per_octave_ (0), 
        min_contrast_ (-std::numeric_limits<float>::max ()), scale_idx_ (-1), 
        out_fields_ (), getFieldValue_ ()
      {
        name_ = "SIFTKeypoint";
      }

      void 
      setScales (float min_scale, int nr_octaves, int nr_scales_per_octave);

      void 
      setMinimumContrast (float min_contrast);

    protected:
      bool
      initCompute ();

      void 
      detectKeypoints (PointCloudOut &output);

    private:
      void 
      detectKeypointsForOctave (const PointCloudIn &input, KdTree &tree, 
                                float base_scale, int nr_scales_per_octave, 
                                PointCloudOut &output);

      void 
      computeScaleSpace (const PointCloudIn &input, KdTree &tree, 
                         const std::vector<float> &scales, 
                         Eigen::MatrixXf &diff_of_gauss);

      void 
      findScaleSpaceExtrema (const PointCloudIn &input, KdTree &tree, 
                             const Eigen::MatrixXf &diff_of_gauss,
                             std::vector<int> &extrema_indices, std::vector<int> &extrema_scales);


      float min_scale_;

      int nr_octaves_;

      int nr_scales_per_octave_;

      float min_contrast_;

      int scale_idx_;

      std::vector<pcl::PCLPointField> out_fields_;

      SIFTKeypointFieldSelector<PointInT> getFieldValue_;
  };
}

#include <pcl/keypoints/impl/sift_keypoint.hpp>

#endif // #ifndef PCL_SIFT_KEYPOINT_H_