CLandmark.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/math/CMatrixF.h>
#include <mrpt/math/TPoint3D.h>
#include <mrpt/obs/CObservation.h>  // INVALID_LANDMARK_ID
#include <mrpt/poses/CPoint3D.h>
#include <mrpt/poses/CPointPDFGaussian.h>
#include <mrpt/serialization/CSerializable.h>
#include <mrpt/system/datetime.h>
#include <mrpt/vision/CFeature.h>

#include <memory>

namespace mrpt::maps
{
/** The class for storing "landmarks" (visual or laser-scan-extracted
 * features,...)
 *
 *  The descriptors for each kind of descriptor are stored in the vector
 * "features", which
 *   will typically consists of only 1 element, or 2 elements for landmarks
 * obtained from stereo images.
 *
 * \sa CLandmarksMap
 * \ingroup mrpt_vision_grp
 */
class CLandmark : public mrpt::serialization::CSerializable
{
    DEFINE_SERIALIZABLE(CLandmark, mrpt::maps)

   public:
    /** The type for the IDs of landmarks. */
    using TLandmarkID = int64_t;

    /** The set of features from which the landmark comes. */
    std::vector<mrpt::vision::CFeature> features;

    /** The mean of the landmark 3D position. */
    mrpt::math::TPoint3D pose_mean;
    /** The "normal" to the landmark, i.e. a unitary 3D vector towards the
     * viewing direction, or a null vector if not applicable */
    mrpt::math::TPoint3D normal;
    float pose_cov_11{}, pose_cov_22{}, pose_cov_33{}, pose_cov_12{},
        pose_cov_13{}, pose_cov_23{};

    /** An ID for the landmark (see details next...)
     *  This ID was introduced in the version 3 of this class (21/NOV/2006),
     *and its aim is
     *  to provide a way for easily establishing correspondences between
     *landmarks detected
     *  in sequential image frames. Thus, the management of this field should
     *be:
     *      - In 'servers' (classes/modules/... that detect landmarks from
     *images):
     *A different ID must be assigned to every landmark (e.g. a sequential
     *counter), BUT only in the case of being sure of the correspondence of one
     *landmark with another one in the past (e.g. tracking).
     *      - In 'clients': This field can be ignored, but if it is used, the
     *advantage is solving the correspondence between landmarks detected in
     *consequentive instants of time: Two landmarks with the same ID
     *<b>correspond</b> to the same physical feature, BUT it should not be
     *expected the inverse to be always true.
     *
     * Note that this field is never fill out automatically, it must be set by
     *the programmer if used.
     */
    TLandmarkID ID{INVALID_LANDMARK_ID};

    /** The last time that this landmark was observed. */
    mrpt::system::TTimeStamp timestampLastSeen{INVALID_TIMESTAMP};

    /** The number of times that this landmark has been seen. */
    uint32_t seenTimesCount{0};

    /** Returns the pose as an object:
     */
    void getPose(mrpt::poses::CPointPDFGaussian& p) const;

    void getPose(mrpt::poses::CPoint3D& p, mrpt::math::CMatrixDouble& COV) const
    {
        mrpt::poses::CPointPDFGaussian pdf;
        getPose(pdf);
        p = pdf.mean;
        COV = mrpt::math::CMatrixDouble(pdf.cov);
    }

    /** Sets the pose from an object:
     */
    void setPose(const mrpt::poses::CPointPDFGaussian& p);

    /** Gets the type of the first feature in its feature vector. The vector
     * must not be empty.
     */
    mrpt::vision::TKeyPointMethod getType() const
    {
        ASSERT_(!features.empty());
        return features[0].type;
    }

    /** Creates one feature in the vector "features", calling the appropriate
     * constructor of the smart pointer, so after calling this method
     * "features[0]" is a valid pointer to a CFeature object.
     */
    void createOneFeature() { features.resize(1); }

    /** Default constructor */
    CLandmark() = default;

    /** Virtual destructor  */
    ~CLandmark() override;

   protected:
    /** Auxiliary variable
     */
    static TLandmarkID m_counterIDs;

};  // End of class definition

}  // namespace mrpt::maps