CPosePDFGaussian.h

Go to the documentation of this file.

/* +------------------------------------------------------------------------+
   |                     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 CPosePDFGaussian_H
#define CPosePDFGaussian_H
 
#include <mrpt/poses/CPosePDF.h>
#include <mrpt/math/CMatrixFixedNumeric.h>
 
namespace mrpt
{
namespace poses
{
class CPose3DPDF;
class CPoint2DPDFGaussian;
 
/** Declares a class that represents a Probability Density  function (PDF) of a
 * 2D pose \f$ p(\mathbf{x}) = [x ~ y ~ \phi ]^t \f$.
 *
 *   This class implements that PDF using a mono-modal Gaussian distribution.
 * See mrpt::poses::CPosePDF for more details.
 *
 * \sa CPose2D, CPosePDF, CPosePDFParticles
 * \ingroup poses_pdf_grp
 */
class CPosePDFGaussian : public CPosePDF
{
        DEFINE_SERIALIZABLE(CPosePDFGaussian)
 
   protected:
        /** Assures the symmetry of the covariance matrix (eventually certain
         * operations in the math-coprocessor lead to non-symmetric matrixes!)
          */
        void assureSymmetry();
 
   public:
        /** @name Data fields
                @{ */
 
        /** The mean value */
        CPose2D mean;
        /** The 3x3 covariance matrix */
        mrpt::math::CMatrixDouble33 cov;
 
        /** @} */
 
        inline const CPose2D& getPoseMean() const { return mean; }
        inline CPose2D& getPoseMean() { return mean; }
        /** Default constructor
          */
        CPosePDFGaussian();
 
        /** Constructor
          */
        explicit CPosePDFGaussian(const CPose2D& init_Mean);
 
        /** Constructor
          */
        CPosePDFGaussian(
                const CPose2D& init_Mean, const mrpt::math::CMatrixDouble33& init_Cov);
 
        /** Copy constructor, including transformations between other PDFs */
        explicit CPosePDFGaussian(const CPosePDF& o) { copyFrom(o); }
        /** Copy constructor, including transformations between other PDFs */
        explicit CPosePDFGaussian(const CPose3DPDF& o) { copyFrom(o); }
        /** Returns an estimate of the pose, (the mean, or mathematical expectation
         * of the PDF).
          * \sa getCovariance
          */
        void getMean(CPose2D& mean_pose) const override { mean_pose = mean; }
        /** Returns an estimate of the pose covariance matrix (3x3 cov matrix) and
         * the mean, both at once.
          * \sa getMean
          */
        void getCovarianceAndMean(
                mrpt::math::CMatrixDouble33& out_cov,
                CPose2D& mean_point) const override
        {
                mean_point = mean;
                out_cov = this->cov;
        }
 
        /** Copy operator, translating if necesary (for example, between particles
         * and gaussian representations) */
        void copyFrom(const CPosePDF& o) override;
 
        /** Copy operator, translating if necesary (for example, between particles
         * and gaussian representations) */
        void copyFrom(const CPose3DPDF& o);
 
        /** Save PDF's particles to a text file, containing the 2D pose in the first
         * line, then the covariance matrix in next 3 lines. */
        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;
 
        /** 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 CPose2D& newReferenceBase);
 
        /** Rotate the covariance matrix by replacing it by \f$
         * \mathbf{R}~\mathbf{COV}~\mathbf{R}^t \f$, where \f$ \mathbf{R} = \left[
         * \begin{array}{ccc} \cos\alpha & -\sin\alpha & 0 \\ \sin\alpha &
         * \cos\alpha & 0 \\ 0 & 0 & 1 \end{array}\right] \f$.
          */
        void rotateCov(const double ang);
 
        /** Set \f$ this = x1 \ominus x0 \f$ , computing the mean using the "-"
         * operator and the covariances through the corresponding Jacobians (For
         * 'x0' and 'x1' being independent variables!). */
        void inverseComposition(
                const CPosePDFGaussian& x, const CPosePDFGaussian& ref);
 
        /** Set \f$ this = x1 \ominus x0 \f$ , computing the mean using the "-"
         * operator and the covariances through the corresponding Jacobians (Given
         * the 3x3 cross-covariance matrix of variables x0 and x1). */
        void inverseComposition(
                const CPosePDFGaussian& x1, const CPosePDFGaussian& x0,
                const mrpt::math::CMatrixDouble33& COV_01);
 
        /** Draws a single sample from the distribution
          */
        void drawSingleSample(CPose2D& outPart) const override;
 
        /** Draws a number of samples from the distribution, and saves as a list of
         * 1x3 vectors, where each row contains a (x,y,phi) datum.
          */
        void drawManySamples(
                size_t N,
                std::vector<mrpt::math::CVectorDouble>& outSamples) const override;
 
        /** Bayesian fusion of two points gauss. distributions, then save the result
          *in this object.
          *  The process is as follows:<br>
          *             - (x1,S1): Mean and variance of the p1 distribution.
          *             - (x2,S2): Mean and variance of the p2 distribution.
          *             - (x,S): Mean and variance of the resulting distribution.
          *
          *    S = (S1<sup>-1</sup> + S2<sup>-1</sup>)<sup>-1</sup>;
          *    x = S * ( S1<sup>-1</sup>*x1 + S2<sup>-1</sup>*x2 );
          */
        void bayesianFusion(
                const CPosePDF& p1, const CPosePDF& p2,
                const double minMahalanobisDistToDrop = 0) override;
 
        /** Returns a new PDF such as: NEW_PDF = (0,0,0) - THIS_PDF
          */
        void inverse(CPosePDF& o) const override;
 
        /** Makes: thisPDF = thisPDF + Ap, where "+" is pose composition (both the
         * mean, and the covariance matrix are updated). */
        void operator+=(const CPose2D& Ap);
 
        /** Evaluates the PDF at a given point. */
        double evaluatePDF(const CPose2D& x) const;
 
        /** Evaluates the ratio PDF(x) / PDF(MEAN), that is, the normalized PDF in
         * the range [0,1]. */
        double evaluateNormalizedPDF(const CPose2D& x) const;
 
        /** Computes the Mahalanobis distance between the centers of two Gaussians.
         */
        double mahalanobisDistanceTo(const CPosePDFGaussian& theOther);
 
        /** Substitutes the diagonal elements if (square) they are below some given
         * minimum values (Use this before bayesianFusion, for example, to avoid
         * inversion of singular matrixes, etc...)  */
        void assureMinCovariance(const double& minStdXY, const double& minStdPhi);
 
        /** Makes: thisPDF = thisPDF + Ap, where "+" is pose composition (both the
         * mean, and the covariance matrix are updated) (see formulas in
         * jacobiansPoseComposition ). */
        void operator+=(const CPosePDFGaussian& Ap);
 
        /** Makes: thisPDF = thisPDF - Ap, where "-" is pose inverse composition
         * (both the mean, and the covariance matrix are updated) */
        inline void operator-=(const CPosePDFGaussian& ref)
        {
                this->inverseComposition(*this, ref);
        }
 
        /** Returns the PDF of the 2D point \f$ g = q \oplus l\f$ with "q"=this pose
         * and "l" a point without uncertainty */
        void composePoint(
                const mrpt::math::TPoint2D& l, CPoint2DPDFGaussian& g) const;
 
};  // End of class def.
 
/** Pose compose operator: RES = A (+) B , computing both the mean and the
 * covariance */
CPosePDFGaussian operator+(
        const CPosePDFGaussian& a, const CPosePDFGaussian& b);
 
/** Pose inverse compose operator: RES = A (-) B , computing both the mean and
 * the covariance */
CPosePDFGaussian operator-(
        const CPosePDFGaussian& a, const CPosePDFGaussian& b);
 
/** Dumps the mean and covariance matrix to a text stream. */
std::ostream& operator<<(std::ostream& out, const CPosePDFGaussian& obj);
 
/** Returns the Gaussian distribution of \f$ \mathbf{C} \f$, for \f$ \mathbf{C}
 * = \mathbf{A} \oplus \mathbf{B} \f$. */
poses::CPosePDFGaussian operator+(
        const mrpt::poses::CPose2D& A, const mrpt::poses::CPosePDFGaussian& B);
 
bool operator==(const CPosePDFGaussian& p1, const CPosePDFGaussian& p2);
 
}  // End of namespace
}  // End of namespace
 
#endif