CICP.h

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/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2014, 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 CICP_H
#define CICP_H

#include <mrpt/slam/CMetricMapsAlignmentAlgorithm.h>
#include <mrpt/utils/CLoadableOptions.h>

namespace mrpt
{
        namespace slam
        {
                using namespace poses;

                /** The ICP algorithm selection, used in mrpt::slam::CICP::options.
                  *  For details on the algorithms refer to http://www.mrpt.org/Scan_Matching_Algorithms
                  * \ingroup mrpt_slam_grp
                  */
                enum TICPAlgorithm
                {
                        icpClassic = 0,
                        icpLevenbergMarquardt,
                        icpIKF
                };

                /** Several implementations of ICP (Iterative closest point) algorithms for aligning two point maps or a point map wrt a grid map.
                 *
                 *  CICP::AlignPDF() or CICP::Align() are the two main entry points of the algorithm.
                 *
                 *  To choose among existing ICP algorithms or customizing their parameters, see CICP::TConfigParams and the member \a options.
                 *
                 *  There exists an extension of the original ICP algorithm that provides multihypotheses-support for the correspondences, and which generates a Sum-of-Gaussians (SOG)
                 *    PDF as output. See scanmatching::robustRigidTransformation.
                 *
                 * For further details on the implemented methods, check the web:
                 *   http://www.mrpt.org/Iterative_Closest_Point_(ICP)_and_other_matching_algorithms
                 *
                 *  For a paper explaining some of the basic equations, see for example:
                 *   J. Martinez, J. Gonzalez, J. Morales, A. Mandow, A. Garcia-Cerezo,
                 *   "Mobile robot motion estimation by 2D scan matching with genetic and iterative closest point algorithms",
                 *    Journal of Field Robotics, vol. 23, no. 1, pp. 21-34, 2006. ( http://babel.isa.uma.es/~jlblanco/papers/martinez2006gil.pdf )
                 *
                 * \sa CMetricMapsAlignmentAlgorithm
                 * \ingroup mrpt_slam_grp
                 */
                class SLAM_IMPEXP  CICP : public CMetricMapsAlignmentAlgorithm
                {
                public:
                        /** The ICP algorithm configuration data
                         */
                        class SLAM_IMPEXP TConfigParams : public utils::CLoadableOptions
                        {
                        public:
                                TConfigParams();        //!< Initializer for default values:

                                void  loadFromConfigFile(
                                        const mrpt::utils::CConfigFileBase  &source,
                                        const std::string &section); //!< See utils::CLoadableOptions

                                void  dumpToTextStream(CStream  &out) const; //!<See utils::CLoadableOptions


                                /** The algorithm to use (default: icpClassic)
                                  *  See http://www.mrpt.org/Scan_Matching_Algorithms for details.
                                  */
                                TICPAlgorithm   ICP_algorithm;

                                bool    onlyClosestCorrespondences;  //!< The usual approach: to consider only the closest correspondence for each local point (Default to true)
                                bool    onlyUniqueRobust; //! Apart of "onlyClosestCorrespondences=true", if this option is enabled only the closest correspondence for each reference point will be kept (default=false).

                                /** @name Termination criteria
                                    @{ */
                                unsigned int    maxIterations;  //!< Maximum number of iterations to run.
                                float           minAbsStep_trans; //!< If the correction in all translation coordinates (X,Y,Z) is below this threshold (in meters), iterations are terminated (Default:1e-6)
                                float           minAbsStep_rot;   //!< If the correction in all rotation coordinates (yaw,pitch,roll) is below this threshold (in radians), iterations are terminated (Default:1e-6)
                                /** @} */

                                float   thresholdDist,thresholdAng; //!< Initial threshold distance for two points to become a correspondence.
                                float   ALFA;  //!< The scale factor for threshold everytime convergence is achieved.
                                float   smallestThresholdDist;  //!< The size for threshold such that iterations will stop, since it is considered precise enough.

                                /** This is the normalization constant \f$ \sigma^2_p \f$ that is used to scale the whole 3x3 covariance.
                                  *  This has a default value of \f$ (0.02)^2 \f$, that is, a 2cm sigma.
                                  *  See the paper: ....
                                  */
                                float   covariance_varPoints;

                                bool    doRANSAC;  //!< Perform a RANSAC step after the ICP convergence, to obtain a better estimation of the pose PDF.

                                /** RANSAC-step options:
                                  * \sa CICP::robustRigidTransformation
                                  */
                                unsigned int    ransac_minSetSize,ransac_maxSetSize,ransac_nSimulations;

                                /** RANSAC-step options:
                                  * \sa CICP::robustRigidTransformation
                                  */
                                float                   ransac_mahalanobisDistanceThreshold;

                                /** RANSAC-step option: The standard deviation in X,Y of landmarks/points which are being matched (used to compute covariances in the SoG)
                                  * \sa CICP::robustRigidTransformation
                                  */
                                float                   normalizationStd;

                                /** RANSAC-step options:
                                  * \sa CICP::robustRigidTransformation
                                  */
                                bool                    ransac_fuseByCorrsMatch;

                                /** RANSAC-step options:
                                  * \sa CICP::robustRigidTransformation
                                  */
                                float                   ransac_fuseMaxDiffXY, ransac_fuseMaxDiffPhi;

                                /** Cauchy kernel rho, for estimating the optimal transformation covariance, in meters (default = 0.07m). */
                                float                   kernel_rho;

                                /** Whether to use kernel_rho to smooth distances, or use distances directly (default=true) */
                                bool                    use_kernel;

                                /** The size of the perturbance in x & y used to estimate the Jacobians of the square error (in LM & IKF methods, default=0.05).*/
                                float                   Axy_aprox_derivatives;

                                /** The initial value of the lambda parameter in the LM method (default=1e-4). */
                                float                   LM_initial_lambda;

                                /** Skip the computation of the covariance (saves some time) (default=false) */
                                bool                    skip_cov_calculation;

                                /** Skip the (sometimes) expensive evaluation of the term 'quality' at ICP output (Default=true) */
                                bool            skip_quality_calculation; 

                                /** Decimation of the point cloud being registered against the reference one (default=5) - set to 1 to have the older (MRPT <0.9.5) behavior
                                  *  of not approximating ICP by ignoring the correspondence of some points. The speed-up comes from a decimation of the number of KD-tree queries,
                                  *  the most expensive step in ICP.
                                  */
                                uint32_t        corresponding_points_decimation;

                        };

                        TConfigParams  options; //!< The options employed by the ICP align.


                        /** Constructor with the default options */
                        CICP() : options() { }
                        /** Constructor that directly set the ICP params from a given struct \sa options */
                        CICP(const TConfigParams &icpParams) : options(icpParams) { }

                        virtual ~CICP() { }     //!< Destructor


                        /** The ICP algorithm return information.
                         */
                        struct SLAM_IMPEXP TReturnInfo
                        {
                                TReturnInfo() :
                                        cbSize(sizeof(TReturnInfo)),
                                        nIterations(0),
                                        goodness(0),
                                        quality(0)
                                {
                                }

                                /** Size in bytes of this struct: Must be set correctly before using it */
                                unsigned int    cbSize;

                                /** The number of executed iterations until convergence.
                                 */
                                unsigned short  nIterations;

                                /** A goodness measure for the alignment, it is a [0,1] range indicator of percentage of correspondences.
                                 */
                                float                   goodness;

                                /** A measure of the 'quality' of the local minimum of the sqr. error found by the method.
                                  * Higher values are better. Low values will be found in ill-conditioned situations (e.g. a corridor).
                                  */
                                float                   quality;
                        };

                        /** An implementation of CMetricMapsAlignmentAlgorithm for the case of a point maps and a occupancy grid/point map.
                         *
                         *  This method computes the PDF of the displacement (relative pose) between
                         *   two maps: <b>the relative pose of m2 with respect to m1</b>. This pose
                         *   is returned as a PDF rather than a single value.
                         *
                         *  \note This method can be configurated with "CICP::options"
                         *  \note The output PDF is a CPosePDFGaussian if "doRANSAC=false", or a CPosePDFSOG otherwise.
                         *
                         * \param m1                    [IN] The first map (CAN BE A mrpt::poses::CPointsMap derived class or a mrpt::slam::COccupancyGrid2D class)
                         * \param m2                    [IN] The second map. (MUST BE A mrpt::poses::CPointsMap derived class)The pose of this map respect to m1 is to be estimated.
                         * \param initialEstimationPDF  [IN] An initial gross estimation for the displacement.
                         * \param runningTime   [OUT] A pointer to a container for obtaining the algorithm running time in seconds, or NULL if you don't need it.
                         * \param info                  [OUT] A pointer to a CICP::TReturnInfo, or NULL if it isn't needed.
                         *
                         * \return A smart pointer to the output estimated pose PDF.
                         *
                         * \sa CMetricMapsAlignmentAlgorithm, CICP::options, CICP::TReturnInfo
                         */
                        CPosePDFPtr AlignPDF(
                                        const CMetricMap                *m1,
                                        const CMetricMap                *m2,
                                        const CPosePDFGaussian  &initialEstimationPDF,
                                        float                                   *runningTime = NULL,
                                        void                                    *info = NULL );

                        /** Align a pair of metric maps, aligning the full 6D pose.
                         *   The meaning of some parameters are implementation dependant,
                         *    so look at the derived classes for more details.
                         *  The goal is to find a PDF for the pose displacement between
                         *   maps, that is, <b>the pose of m2 relative to m1</b>. This pose
                         *   is returned as a PDF rather than a single value.
                         *
                         *  \note This method can be configurated with a "options" structure in the implementation classes.
                         *
                         * \param m1                    [IN] The first map (MUST BE A COccupancyGridMap2D  derived class)
                         * \param m2                    [IN] The second map. (MUST BE A CPointsMap derived class) The pose of this map respect to m1 is to be estimated.
                         * \param initialEstimationPDF  [IN] An initial gross estimation for the displacement.
                         * \param runningTime   [OUT] A pointer to a container for obtaining the algorithm running time in seconds, or NULL if you don't need it.
                         * \param info                  [OUT] See derived classes for details, or NULL if it isn't needed.
                         *
                         * \return A smart pointer to the output estimated pose PDF.
                         * \sa CICP
                         */
                        CPose3DPDFPtr Align3DPDF(
                                        const CMetricMap                *m1,
                                        const CMetricMap                *m2,
                                        const CPose3DPDFGaussian        &initialEstimationPDF,
                                        float                                   *runningTime = NULL,
                                        void                                    *info = NULL );


                protected:
                        /** Computes:
                          *  \f[ K(x^2) = \frac{x^2}{x^2+\rho^2}  \f]
                          *  or just return the input if options.useKernel = false.
                          */
                        float kernel(const float &x2, const float &rho2);

                        /** The internal method implementing CICP::AlignPDF when options.ICP_algorithm is icpClassic.
                          */
                        CPosePDFPtr ICP_Method_Classic(
                                        const CMetricMap                *m1,
                                        const CMetricMap                *m2,
                                        const CPosePDFGaussian  &initialEstimationPDF,
                                        TReturnInfo                             &outInfo );

                        /** The internal method implementing CICP::AlignPDF when options.ICP_algorithm is icpLevenbergMarquardt.
                          */
                        CPosePDFPtr ICP_Method_LM(
                                        const CMetricMap                *m1,
                                        const CMetricMap                *m2,
                                        const CPosePDFGaussian  &initialEstimationPDF,
                                        TReturnInfo                             &outInfo );

                        /** The internal method implementing CICP::AlignPDF when options.ICP_algorithm is icpIKF.
                          */
                        CPosePDFPtr ICP_Method_IKF(
                                        const CMetricMap                *m1,
                                        const CMetricMap                *m2,
                                        const CPosePDFGaussian  &initialEstimationPDF,
                                        TReturnInfo                             &outInfo );

                        /** The internal method implementing CICP::Align3DPDF when options.ICP_algorithm is icpClassic.
                          */
                        CPose3DPDFPtr ICP3D_Method_Classic(
                                        const CMetricMap                *m1,
                                        const CMetricMap                *m2,
                                        const CPose3DPDFGaussian &initialEstimationPDF,
                                        TReturnInfo                             &outInfo );


                };

        } // End of namespace
} // End of namespace

#endif