CPointPDFSOG.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2018, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */
#ifndef CPointPDFSOG_H
#define CPointPDFSOG_H
 
#include <mrpt/poses/CPointPDF.h>
#include <mrpt/poses/CPointPDFGaussian.h>
#include <mrpt/math/CMatrix.h>
#include <mrpt/math/CMatrixD.h>
 
namespace mrpt
{
namespace poses
{
/** Declares a class that represents a Probability Density function (PDF) of a
 * 3D point \f$ p(\mathbf{x}) = [x ~ y ~ z ]^t \f$.
 *   This class implements that PDF as the following multi-modal Gaussian
 * distribution:
 *
 * \f$ p(\mathbf{x}) = \sum\limits_{i=1}^N \omega^i \mathcal{N}( \mathbf{x} ;
 * \bar{\mathbf{x}}^i, \mathbf{\Sigma}^i )  \f$
 *
 *  Where the number of modes N is the size of CPointPDFSOG::m_modes
 *
 *  See mrpt::poses::CPointPDF for more details.
 *
 * \sa CPointPDF, CPosePDF,
 * \ingroup poses_pdf_grp
 */
class CPointPDFSOG : public CPointPDF
{
        DEFINE_SERIALIZABLE(CPointPDFSOG)
 
   public:
        /** The struct for each mode:
         */
        struct TGaussianMode
        {
                TGaussianMode() : val(), log_w(0) {}
                CPointPDFGaussian val;
 
                /** The log-weight
                  */
                double log_w;
        };
 
        using CListGaussianModes = std::deque<TGaussianMode>;
        using const_iterator = std::deque<TGaussianMode>::const_iterator;
        using iterator = std::deque<TGaussianMode>::iterator;
 
   protected:
        /** Assures the symmetry of the covariance matrix (eventually certain
         * operations in the math-coprocessor lead to non-symmetric matrixes!)
          */
        void assureSymmetry();
 
        /** The list of SOG modes */
        CListGaussianModes m_modes;
 
   public:
        /** Default constructor
          * \param nModes The initial size of CPointPDFSOG::m_modes
          */
        CPointPDFSOG(size_t nModes = 1);
 
        /** Clear all the gaussian modes */
        void clear();
 
        /** Access to individual beacons */
        const TGaussianMode& operator[](size_t i) const
        {
                ASSERT_(i < m_modes.size());
                return m_modes[i];
        }
        /** Access to individual beacons */
        TGaussianMode& operator[](size_t i)
        {
                ASSERT_(i < m_modes.size());
                return m_modes[i];
        }
 
        /** Access to individual beacons */
        const TGaussianMode& get(size_t i) const
        {
                ASSERT_(i < m_modes.size());
                return m_modes[i];
        }
        /** Access to individual beacons */
        TGaussianMode& get(size_t i)
        {
                ASSERT_(i < m_modes.size());
                return m_modes[i];
        }
 
        /** Inserts a copy of the given mode into the SOG */
        void push_back(const TGaussianMode& m) { m_modes.push_back(m); }
        iterator begin() { return m_modes.begin(); }
        iterator end() { return m_modes.end(); }
        const_iterator begin() const { return m_modes.begin(); }
        const_iterator end() const { return m_modes.end(); }
        iterator erase(iterator i) { return m_modes.erase(i); }
        /** Resize the number of SOG modes */
        void resize(const size_t N);
        /** Return the number of Gaussian modes. */
        size_t size() const { return m_modes.size(); }
        /** Return whether there is any Gaussian mode. */
        bool empty() const { return m_modes.empty(); }
        /** Returns an estimate of the point, (the mean, or mathematical expectation
         * of the PDF) \sa getCovariance   */
        void getMean(CPoint3D& mean_point) const override;
 
        /** Returns an estimate of the point covariance matrix (3x3 cov matrix) and
         * the mean, both at once. \sa getMean */
        void getCovarianceAndMean(
                mrpt::math::CMatrixDouble33& cov, CPoint3D& mean_point) const override;
 
        /** Normalize the weights in m_modes such as the maximum log-weight is 0 */
        void normalizeWeights();
 
        /** Return the Gaussian mode with the highest likelihood (or an empty
         * Gaussian if there are no modes in this SOG) */
        void getMostLikelyMode(CPointPDFGaussian& outVal) const;
 
        /** Computes the "Effective sample size" (typical measure for Particle
         * Filters), applied to the weights of the individual Gaussian modes, as a
         * measure of the equality of the modes (in the range [0,total # of modes]).
         */
        double ESS() const;
 
        /** Copy operator, translating if necesary (for example, between particles
         * and gaussian representations) */
        void copyFrom(const CPointPDF& o) override;
 
        /** Save the density to a text file, with the following format:
          *  There is one row per Gaussian "mode", and each row contains 10
         * elements:
          *   - w (The weight)
          *   - x_mean (gaussian mean value)
          *   - y_mean (gaussian mean value)
          *   - x_mean (gaussian mean value)
          *   - C11 (Covariance elements)
          *   - C22 (Covariance elements)
          *   - C33 (Covariance elements)
          *   - C12 (Covariance elements)
          *   - C13 (Covariance elements)
          *   - C23 (Covariance elements)
          *
         */
        bool saveToTextFile(const std::string& file) const override;
 
        /** this = p (+) this. This can be used to convert a PDF from local
         * coordinates to global, providing the point (newReferenceBase) from which
          *   "to project" the current pdf. Result PDF substituted the currently
         * stored one in the object. */
        void changeCoordinatesReference(const CPose3D& newReferenceBase) override;
 
        /** Draw a sample from the pdf. */
        void drawSingleSample(CPoint3D& outSample) const override;
 
        /** Bayesian fusion of two point distributions (product of two
         * distributions->new distribution), then save the result in this object
         * (WARNING: See implementing classes to see classes that can and cannot be
         * mixtured!)
          * \param p1 The first distribution to fuse
          * \param p2 The second distribution to fuse
          * \param minMahalanobisDistToDrop If set to different of 0, the result of
         * very separate Gaussian modes (that will result in negligible components)
         * in SOGs will be dropped to reduce the number of modes in the output.
          */
        void bayesianFusion(
                const CPointPDF& p1, const CPointPDF& p2,
                const double minMahalanobisDistToDrop = 0) override;
 
        /** Evaluates the PDF within a rectangular grid and saves the result in a
         * matrix (each row contains values for a fixed y-coordinate value).
          */
        void evaluatePDFInArea(
                float x_min, float x_max, float y_min, float y_max, float resolutionXY,
                float z, mrpt::math::CMatrixD& outMatrix, bool sumOverAllZs = false);
 
        /** Evaluates the PDF at a given point */
        double evaluatePDF(const CPoint3D& x, bool sumOverAllZs) const;
 
};  // End of class def.
}  // End of namespace
}  // End of namespace
#endif