CPointsMap.cpp

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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          |
   +------------------------------------------------------------------------+ */

#include "maps-precomp.h"  // Precomp header

#include <mrpt/config/CConfigFile.h>
#include <mrpt/maps/CPointsMap.h>
#include <mrpt/maps/CSimplePointsMap.h>
#include <mrpt/math/TPose2D.h>
#include <mrpt/math/geometry.h>
#include <mrpt/obs/CObservation2DRangeScan.h>
#include <mrpt/obs/CObservation3DRangeScan.h>
#include <mrpt/obs/CObservationPointCloud.h>
#include <mrpt/obs/CObservationRange.h>
#include <mrpt/obs/CObservationVelodyneScan.h>
#include <mrpt/opengl/CPointCloud.h>
#include <mrpt/opengl/CPointCloudColoured.h>
#include <mrpt/serialization/CArchive.h>
#include <mrpt/system/CTicTac.h>
#include <mrpt/system/CTimeLogger.h>
#include <mrpt/system/os.h>

#include <mrpt/core/SSE_macros.h>
#include <mrpt/core/SSE_types.h>

#if MRPT_HAS_MATLAB
#include <mexplus.h>
#endif

using namespace mrpt::poses;
using namespace mrpt::maps;
using namespace mrpt::math;
using namespace mrpt::tfest;
using namespace mrpt::obs;
using namespace mrpt::img;
using namespace mrpt::system;
using namespace std;

IMPLEMENTS_VIRTUAL_SERIALIZABLE(CPointsMap, CMetricMap, mrpt::maps)

/*---------------------------------------------------------------
                        Constructor
  ---------------------------------------------------------------*/
CPointsMap::CPointsMap()
    : insertionOptions(), likelihoodOptions(), m_x(), m_y(), m_z()

{
    mark_as_modified();
}

/*---------------------------------------------------------------
                        Destructor
  ---------------------------------------------------------------*/
CPointsMap::~CPointsMap() = default;
/*---------------------------------------------------------------
                    save2D_to_text_file
  Save to a text file. In each line there are a point coordinates.
    Returns false if any error occured, true elsewere.
  ---------------------------------------------------------------*/
bool CPointsMap::save2D_to_text_file(const string& file) const
{
    FILE* f = os::fopen(file.c_str(), "wt");
    if (!f) return false;

    for (unsigned int i = 0; i < m_x.size(); i++)
        os::fprintf(f, "%f %f\n", m_x[i], m_y[i]);

    os::fclose(f);
    return true;
}

/*---------------------------------------------------------------
                    save3D_to_text_file
  Save to a text file. In each line there are a point coordinates.
    Returns false if any error occured, true elsewere.
  ---------------------------------------------------------------*/
bool CPointsMap::save3D_to_text_file(const string& file) const
{
    FILE* f = os::fopen(file.c_str(), "wt");
    if (!f) return false;

    for (unsigned int i = 0; i < m_x.size(); i++)
        os::fprintf(f, "%f %f %f\n", m_x[i], m_y[i], m_z[i]);

    os::fclose(f);
    return true;
}

/*---------------------------------------------------------------
                    load2Dor3D_from_text_file
  Load from a text file. In each line there are a point coordinates.
    Returns false if any error occured, true elsewere.
  ---------------------------------------------------------------*/
bool CPointsMap::load2Dor3D_from_text_file(
    const std::string& file, const bool is_3D)
{
    MRPT_START

    mark_as_modified();

    FILE* f = os::fopen(file.c_str(), "rt");
    if (!f) return false;

    char str[1024];
    char *ptr, *ptr1, *ptr2, *ptr3;

    // Clear current map:
    this->clear();

    while (!feof(f))
    {
        // Read one string line:
        str[0] = 0;
        if (!fgets(str, sizeof(str), f)) break;

        // Find the first digit:
        ptr = str;
        while (ptr[0] && (ptr[0] == ' ' || ptr[0] == '\t' || ptr[0] == '\r' ||
                          ptr[0] == '\n'))
            ptr++;

        // And try to parse it:
        float xx = strtod(ptr, &ptr1);
        if (ptr1 != str)
        {
            float yy = strtod(ptr1, &ptr2);
            if (ptr2 != ptr1)
            {
                if (!is_3D)
                {
                    this->insertPoint(xx, yy, 0);
                }
                else
                {
                    float zz = strtod(ptr2, &ptr3);
                    if (ptr3 != ptr2)
                    {
                        this->insertPoint(xx, yy, zz);
                    }
                }
            }
        }
    }

    os::fclose(f);
    return true;

    MRPT_END
}

/*---------------------------------------------------------------
  Implements the writing to a mxArray for Matlab
 ---------------------------------------------------------------*/
#if MRPT_HAS_MATLAB
// Add to implement mexplus::from template specialization
IMPLEMENTS_MEXPLUS_FROM(mrpt::maps::CPointsMap)
#endif

mxArray* CPointsMap::writeToMatlab() const
{
#if MRPT_HAS_MATLAB
    MRPT_TODO("Create 3xN array xyz of points coordinates")
    const char* fields[] = {"x", "y", "z"};
    mexplus::MxArray map_struct(
        mexplus::MxArray::Struct(sizeof(fields) / sizeof(fields[0]), fields));

    map_struct.set("x", m_x);
    map_struct.set("y", m_y);
    map_struct.set("z", m_z);
    return map_struct.release();
#else
    THROW_EXCEPTION("MRPT built without MATLAB/Mex support");
#endif
}

/*---------------------------------------------------------------
                    getPoint
            Access to stored points coordinates:
  ---------------------------------------------------------------*/
void CPointsMap::getPoint(size_t index, float& x, float& y) const
{
    ASSERT_BELOW_(index, m_x.size());
    x = m_x[index];
    y = m_y[index];
}
void CPointsMap::getPoint(size_t index, float& x, float& y, float& z) const
{
    ASSERT_BELOW_(index, m_x.size());
    x = m_x[index];
    y = m_y[index];
    z = m_z[index];
}
void CPointsMap::getPoint(size_t index, double& x, double& y) const
{
    ASSERT_BELOW_(index, m_x.size());
    x = m_x[index];
    y = m_y[index];
}
void CPointsMap::getPoint(size_t index, double& x, double& y, double& z) const
{
    ASSERT_BELOW_(index, m_x.size());
    x = m_x[index];
    y = m_y[index];
    z = m_z[index];
}

/*---------------------------------------------------------------
                        getPointsBuffer
 ---------------------------------------------------------------*/
void CPointsMap::getPointsBuffer(
    size_t& outPointsCount, const float*& xs, const float*& ys,
    const float*& zs) const
{
    outPointsCount = size();

    if (outPointsCount > 0)
    {
        xs = &m_x[0];
        ys = &m_y[0];
        zs = &m_z[0];
    }
    else
    {
        xs = ys = zs = nullptr;
    }
}

/*---------------------------------------------------------------
                        clipOutOfRangeInZ
 ---------------------------------------------------------------*/
void CPointsMap::clipOutOfRangeInZ(float zMin, float zMax)
{
    const size_t n = size();
    vector<bool> deletionMask(n);

    // Compute it:
    for (size_t i = 0; i < n; i++)
        deletionMask[i] = (m_z[i] < zMin || m_z[i] > zMax);

    // Perform deletion:
    applyDeletionMask(deletionMask);

    mark_as_modified();
}

/*---------------------------------------------------------------
                        clipOutOfRange
 ---------------------------------------------------------------*/
void CPointsMap::clipOutOfRange(const TPoint2D& p, float maxRange)
{
    size_t i, n = size();
    vector<bool> deletionMask;

    // The deletion mask:
    deletionMask.resize(n);

    const auto max_sq = maxRange * maxRange;

    // Compute it:
    for (i = 0; i < n; i++)
        deletionMask[i] = square(p.x - m_x[i]) + square(p.y - m_y[i]) > max_sq;

    // Perform deletion:
    applyDeletionMask(deletionMask);

    mark_as_modified();
}

void CPointsMap::determineMatching2D(
    const mrpt::maps::CMetricMap* otherMap2, const CPose2D& otherMapPose_,
    TMatchingPairList& correspondences, const TMatchingParams& params,
    TMatchingExtraResults& extraResults) const
{
    MRPT_START

    extraResults = TMatchingExtraResults();  // Clear output

    ASSERT_ABOVE_(params.decimation_other_map_points, 0);
    ASSERT_BELOW_(
        params.offset_other_map_points, params.decimation_other_map_points);
    ASSERT_(IS_DERIVED(*otherMap2, CPointsMap));
    const auto* otherMap = static_cast<const CPointsMap*>(otherMap2);

    const TPose2D otherMapPose(
        otherMapPose_.x(), otherMapPose_.y(), otherMapPose_.phi());

    const size_t nLocalPoints = otherMap->size();
    const size_t nGlobalPoints = this->size();
    float _sumSqrDist = 0;
    size_t _sumSqrCount = 0;
    size_t nOtherMapPointsWithCorrespondence =
        0;  // Number of points with one corrs. at least

    float local_x_min = std::numeric_limits<float>::max(),
          local_x_max = -std::numeric_limits<float>::max();
    float global_x_min = std::numeric_limits<float>::max(),
          global_x_max = -std::numeric_limits<float>::max();
    float local_y_min = std::numeric_limits<float>::max(),
          local_y_max = -std::numeric_limits<float>::max();
    float global_y_min = std::numeric_limits<float>::max(),
          global_y_max = -std::numeric_limits<float>::max();

    double maxDistForCorrespondenceSquared;
    float x_local, y_local;
    unsigned int localIdx;

    const float *x_other_it, *y_other_it, *z_other_it;

    // Prepare output: no correspondences initially:
    correspondences.clear();
    correspondences.reserve(nLocalPoints);
    extraResults.correspondencesRatio = 0;

    TMatchingPairList _correspondences;
    _correspondences.reserve(nLocalPoints);

    // Nothing to do if we have an empty map!
    if (!nGlobalPoints || !nLocalPoints) return;

    const double sin_phi = sin(otherMapPose.phi);
    const double cos_phi = cos(otherMapPose.phi);

// Do matching only there is any chance of the two maps to overlap:
// -----------------------------------------------------------
// Translate and rotate all local points, while simultaneously
// estimating the bounding box:
#if MRPT_HAS_SSE2
    // Number of 4-floats:
    size_t nPackets = nLocalPoints / 4;

    Eigen::ArrayXf x_locals(nLocalPoints), y_locals(nLocalPoints);

    // load 4 copies of the same value
    const __m128 cos_4val = _mm_set1_ps(cos_phi);
    const __m128 sin_4val = _mm_set1_ps(sin_phi);
    const __m128 x0_4val = _mm_set1_ps(otherMapPose.x);
    const __m128 y0_4val = _mm_set1_ps(otherMapPose.y);

    // For the bounding box:
    __m128 x_mins = _mm_set1_ps(std::numeric_limits<float>::max());
    __m128 x_maxs = _mm_set1_ps(std::numeric_limits<float>::min());
    __m128 y_mins = x_mins;
    __m128 y_maxs = x_maxs;

    const float* ptr_in_x = &otherMap->m_x[0];
    const float* ptr_in_y = &otherMap->m_y[0];
    float* ptr_out_x = &x_locals[0];
    float* ptr_out_y = &y_locals[0];

    for (; nPackets; nPackets--, ptr_in_x += 4, ptr_in_y += 4, ptr_out_x += 4,
                     ptr_out_y += 4)
    {
        const __m128 xs = _mm_loadu_ps(ptr_in_x);  // *Unaligned* load
        const __m128 ys = _mm_loadu_ps(ptr_in_y);

        const __m128 lxs = _mm_add_ps(
            x0_4val,
            _mm_sub_ps(_mm_mul_ps(xs, cos_4val), _mm_mul_ps(ys, sin_4val)));
        const __m128 lys = _mm_add_ps(
            y0_4val,
            _mm_add_ps(_mm_mul_ps(xs, sin_4val), _mm_mul_ps(ys, cos_4val)));
        _mm_store_ps(ptr_out_x, lxs);
        _mm_store_ps(ptr_out_y, lys);

        x_mins = _mm_min_ps(x_mins, lxs);
        x_maxs = _mm_max_ps(x_maxs, lxs);
        y_mins = _mm_min_ps(y_mins, lys);
        y_maxs = _mm_max_ps(y_maxs, lys);
    }

    // Recover the min/max:
    alignas(MRPT_MAX_STATIC_ALIGN_BYTES) float temp_nums[4];

    _mm_store_ps(temp_nums, x_mins);
    local_x_min =
        min(min(temp_nums[0], temp_nums[1]), min(temp_nums[2], temp_nums[3]));
    _mm_store_ps(temp_nums, y_mins);
    local_y_min =
        min(min(temp_nums[0], temp_nums[1]), min(temp_nums[2], temp_nums[3]));
    _mm_store_ps(temp_nums, x_maxs);
    local_x_max =
        max(max(temp_nums[0], temp_nums[1]), max(temp_nums[2], temp_nums[3]));
    _mm_store_ps(temp_nums, y_maxs);
    local_y_max =
        max(max(temp_nums[0], temp_nums[1]), max(temp_nums[2], temp_nums[3]));

    // transform extra pts & update BBox
    for (size_t k = 0; k < nLocalPoints % 4; k++)
    {
        float x = ptr_in_x[k];
        float y = ptr_in_y[k];
        float out_x = otherMapPose.x + cos_phi * x - sin_phi * y;
        float out_y = otherMapPose.y + sin_phi * x + cos_phi * y;

        local_x_min = std::min(local_x_min, out_x);
        local_x_max = std::max(local_x_max, out_x);

        local_y_min = std::min(local_y_min, out_y);
        local_y_max = std::max(local_y_max, out_y);

        ptr_out_x[k] = out_x;
        ptr_out_y[k] = out_y;
    }

#else
    // Non SSE2 version:
    const Eigen::Map<Eigen::Matrix<float, Eigen::Dynamic, 1>> x_org(
        const_cast<float*>(&otherMap->m_x[0]), otherMap->m_x.size(), 1);
    const Eigen::Map<Eigen::Matrix<float, Eigen::Dynamic, 1>> y_org(
        const_cast<float*>(&otherMap->m_y[0]), otherMap->m_y.size(), 1);

    Eigen::Array<float, Eigen::Dynamic, 1> x_locals =
        otherMapPose.x + cos_phi * x_org.array() - sin_phi * y_org.array();
    Eigen::Array<float, Eigen::Dynamic, 1> y_locals =
        otherMapPose.y + sin_phi * x_org.array() + cos_phi * y_org.array();

    local_x_min = x_locals.minCoeff();
    local_y_min = y_locals.minCoeff();
    local_x_max = x_locals.maxCoeff();
    local_y_max = y_locals.maxCoeff();
#endif

    // Find the bounding box:
    float global_z_min, global_z_max;
    this->boundingBox(
        global_x_min, global_x_max, global_y_min, global_y_max, global_z_min,
        global_z_max);

    // Only try doing a matching if there exist any chance of both maps
    // touching/overlaping:
    if (local_x_min > global_x_max || local_x_max < global_x_min ||
        local_y_min > global_y_max || local_y_max < global_y_min)
        return;  // We know for sure there is no matching at all

    // Loop for each point in local map:
    // --------------------------------------------------
    for (localIdx = params.offset_other_map_points,
        x_other_it = &otherMap->m_x[params.offset_other_map_points],
        y_other_it = &otherMap->m_y[params.offset_other_map_points],
        z_other_it = &otherMap->m_z[params.offset_other_map_points];
         localIdx < nLocalPoints;
         x_other_it += params.decimation_other_map_points,
        y_other_it += params.decimation_other_map_points,
        z_other_it += params.decimation_other_map_points,
        localIdx += params.decimation_other_map_points)
    {
        // For speed-up:
        x_local = x_locals[localIdx];  // *x_locals_it;
        y_local = y_locals[localIdx];  // *y_locals_it;

        // Find all the matchings in the requested distance:

        // KD-TREE implementation =================================
        // Use a KD-tree to look for the nearnest neighbor of:
        //   (x_local, y_local, z_local)
        // In "this" (global/reference) points map.

        float tentativ_err_sq;
        unsigned int tentativ_this_idx = kdTreeClosestPoint2D(
            x_local, y_local,  // Look closest to this guy
            tentativ_err_sq  // save here the min. distance squared
        );

        // Compute max. allowed distance:
        maxDistForCorrespondenceSquared = square(
            params.maxAngularDistForCorrespondence *
                std::sqrt(
                    square(params.angularDistPivotPoint.x - x_local) +
                    square(params.angularDistPivotPoint.y - y_local)) +
            params.maxDistForCorrespondence);

        // Distance below the threshold??
        if (tentativ_err_sq < maxDistForCorrespondenceSquared)
        {
            // Save all the correspondences:
            _correspondences.resize(_correspondences.size() + 1);

            TMatchingPair& p = _correspondences.back();

            p.this_idx = tentativ_this_idx;
            p.this_x = m_x[tentativ_this_idx];
            p.this_y = m_y[tentativ_this_idx];
            p.this_z = m_z[tentativ_this_idx];

            p.other_idx = localIdx;
            p.other_x = *x_other_it;
            p.other_y = *y_other_it;
            p.other_z = *z_other_it;

            p.errorSquareAfterTransformation = tentativ_err_sq;

            // At least one:
            nOtherMapPointsWithCorrespondence++;

            // Accumulate the MSE:
            _sumSqrDist += p.errorSquareAfterTransformation;
            _sumSqrCount++;
        }

    }  // For each local point

    // Additional consistency filter: "onlyKeepTheClosest" up to now
    //  led to just one correspondence for each "local map" point, but
    //  many of them may have as corresponding pair the same "global point"!!
    // -------------------------------------------------------------------------
    if (params.onlyUniqueRobust)
    {
        ASSERTMSG_(
            params.onlyKeepTheClosest,
            "ERROR: onlyKeepTheClosest must be also set to true when "
            "onlyUniqueRobust=true.");
        _correspondences.filterUniqueRobustPairs(
            nGlobalPoints, correspondences);
    }
    else
    {
        correspondences.swap(_correspondences);
    }

    // If requested, copy sum of squared distances to output pointer:
    // -------------------------------------------------------------------
    if (_sumSqrCount)
        extraResults.sumSqrDist =
            _sumSqrDist / static_cast<double>(_sumSqrCount);
    else
        extraResults.sumSqrDist = 0;

    // The ratio of points in the other map with corrs:
    extraResults.correspondencesRatio = params.decimation_other_map_points *
                                        nOtherMapPointsWithCorrespondence /
                                        d2f(nLocalPoints);

    MRPT_END
}

/*---------------------------------------------------------------
                changeCoordinatesReference
 ---------------------------------------------------------------*/
void CPointsMap::changeCoordinatesReference(const CPose2D& newBase)
{
    const size_t N = m_x.size();

    const CPose3D newBase3D(newBase);

    for (size_t i = 0; i < N; i++)
        newBase3D.composePoint(
            m_x[i], m_y[i], m_z[i],  // In
            m_x[i], m_y[i], m_z[i]  // Out
        );

    mark_as_modified();
}

/*---------------------------------------------------------------
                changeCoordinatesReference
 ---------------------------------------------------------------*/
void CPointsMap::changeCoordinatesReference(const CPose3D& newBase)
{
    const size_t N = m_x.size();

    for (size_t i = 0; i < N; i++)
        newBase.composePoint(
            m_x[i], m_y[i], m_z[i],  // In
            m_x[i], m_y[i], m_z[i]  // Out
        );

    mark_as_modified();
}

/*---------------------------------------------------------------
                changeCoordinatesReference
 ---------------------------------------------------------------*/
void CPointsMap::changeCoordinatesReference(
    const CPointsMap& other, const CPose3D& newBase)
{
    *this = other;
    changeCoordinatesReference(newBase);
}

/*---------------------------------------------------------------
                isEmpty
 ---------------------------------------------------------------*/
bool CPointsMap::isEmpty() const { return m_x.empty(); }
/*---------------------------------------------------------------
                TInsertionOptions
 ---------------------------------------------------------------*/
CPointsMap::TInsertionOptions::TInsertionOptions()
    : horizontalTolerance(0.05_deg)

{
}

// Binary dump to/read from stream - for usage in derived classes' serialization
void CPointsMap::TInsertionOptions::writeToStream(
    mrpt::serialization::CArchive& out) const
{
    const int8_t version = 0;
    out << version;

    out << minDistBetweenLaserPoints << addToExistingPointsMap
        << also_interpolate << disableDeletion << fuseWithExisting
        << isPlanarMap << horizontalTolerance << maxDistForInterpolatePoints
        << insertInvalidPoints;  // v0
}

void CPointsMap::TInsertionOptions::readFromStream(
    mrpt::serialization::CArchive& in)
{
    int8_t version;
    in >> version;
    switch (version)
    {
        case 0:
        {
            in >> minDistBetweenLaserPoints >> addToExistingPointsMap >>
                also_interpolate >> disableDeletion >> fuseWithExisting >>
                isPlanarMap >> horizontalTolerance >>
                maxDistForInterpolatePoints >> insertInvalidPoints;  // v0
        }
        break;
        default:
            MRPT_THROW_UNKNOWN_SERIALIZATION_VERSION(version);
    }
}

CPointsMap::TLikelihoodOptions::TLikelihoodOptions()

    = default;

void CPointsMap::TLikelihoodOptions::writeToStream(
    mrpt::serialization::CArchive& out) const
{
    const int8_t version = 0;
    out << version;
    out << sigma_dist << max_corr_distance << decimation;
}

void CPointsMap::TLikelihoodOptions::readFromStream(
    mrpt::serialization::CArchive& in)
{
    int8_t version;
    in >> version;
    switch (version)
    {
        case 0:
        {
            in >> sigma_dist >> max_corr_distance >> decimation;
        }
        break;
        default:
            MRPT_THROW_UNKNOWN_SERIALIZATION_VERSION(version);
    }
}

void CPointsMap::TRenderOptions::writeToStream(
    mrpt::serialization::CArchive& out) const
{
    const int8_t version = 0;
    out << version;
    out << point_size << color << int8_t(colormap);
}

void CPointsMap::TRenderOptions::readFromStream(
    mrpt::serialization::CArchive& in)
{
    int8_t version;
    in >> version;
    switch (version)
    {
        case 0:
        {
            in >> point_size >> this->color;
            in.ReadAsAndCastTo<int8_t>(this->colormap);
        }
        break;
        default:
            MRPT_THROW_UNKNOWN_SERIALIZATION_VERSION(version);
    }
}

void CPointsMap::TInsertionOptions::dumpToTextStream(std::ostream& out) const
{
    out << "\n----------- [CPointsMap::TInsertionOptions] ------------ \n\n";

    LOADABLEOPTS_DUMP_VAR(minDistBetweenLaserPoints, double);
    LOADABLEOPTS_DUMP_VAR(maxDistForInterpolatePoints, double);
    LOADABLEOPTS_DUMP_VAR_DEG(horizontalTolerance);

    LOADABLEOPTS_DUMP_VAR(addToExistingPointsMap, bool);
    LOADABLEOPTS_DUMP_VAR(also_interpolate, bool);
    LOADABLEOPTS_DUMP_VAR(disableDeletion, bool);
    LOADABLEOPTS_DUMP_VAR(fuseWithExisting, bool);
    LOADABLEOPTS_DUMP_VAR(isPlanarMap, bool);

    LOADABLEOPTS_DUMP_VAR(insertInvalidPoints, bool);

    out << endl;
}

void CPointsMap::TLikelihoodOptions::dumpToTextStream(std::ostream& out) const
{
    out << "\n----------- [CPointsMap::TLikelihoodOptions] ------------ \n\n";

    LOADABLEOPTS_DUMP_VAR(sigma_dist, double);
    LOADABLEOPTS_DUMP_VAR(max_corr_distance, double);
    LOADABLEOPTS_DUMP_VAR(decimation, int);
}

void CPointsMap::TRenderOptions::dumpToTextStream(std::ostream& out) const
{
    out << "\n----------- [CPointsMap::TRenderOptions] ------------ \n\n";

    LOADABLEOPTS_DUMP_VAR(point_size, float);
    LOADABLEOPTS_DUMP_VAR(color.R, float);
    LOADABLEOPTS_DUMP_VAR(color.G, float);
    LOADABLEOPTS_DUMP_VAR(color.B, float);
    // LOADABLEOPTS_DUMP_VAR(colormap, int);
}
/*---------------------------------------------------------------
                    loadFromConfigFile
  ---------------------------------------------------------------*/
void CPointsMap::TInsertionOptions::loadFromConfigFile(
    const mrpt::config::CConfigFileBase& iniFile, const string& section)
{
    MRPT_LOAD_CONFIG_VAR(minDistBetweenLaserPoints, float, iniFile, section);
    MRPT_LOAD_CONFIG_VAR_DEGREES(horizontalTolerance, iniFile, section);

    MRPT_LOAD_CONFIG_VAR(addToExistingPointsMap, bool, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(also_interpolate, bool, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(disableDeletion, bool, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(fuseWithExisting, bool, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(isPlanarMap, bool, iniFile, section);

    MRPT_LOAD_CONFIG_VAR(maxDistForInterpolatePoints, float, iniFile, section);

    MRPT_LOAD_CONFIG_VAR(insertInvalidPoints, bool, iniFile, section);
}

void CPointsMap::TLikelihoodOptions::loadFromConfigFile(
    const mrpt::config::CConfigFileBase& iniFile, const string& section)
{
    MRPT_LOAD_CONFIG_VAR(sigma_dist, double, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(max_corr_distance, double, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(decimation, int, iniFile, section);
}

void CPointsMap::TRenderOptions::loadFromConfigFile(
    const mrpt::config::CConfigFileBase& iniFile, const string& section)
{
    MRPT_LOAD_CONFIG_VAR(point_size, float, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(color.R, float, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(color.G, float, iniFile, section);
    MRPT_LOAD_CONFIG_VAR(color.B, float, iniFile, section);
    colormap = iniFile.read_enum(section, "colormap", this->colormap);
}

/*---------------------------------------------------------------
                        getAs3DObject
---------------------------------------------------------------*/
void CPointsMap::getAs3DObject(mrpt::opengl::CSetOfObjects::Ptr& outObj) const
{
    MRPT_START
    if (!genericMapParams.enableSaveAs3DObject) return;

    if (renderOptions.colormap == mrpt::img::cmNONE)
    {
        // Single color:
        auto obj = opengl::CPointCloud::Create();
        obj->loadFromPointsMap(this);
        obj->setColor(renderOptions.color);
        obj->setPointSize(renderOptions.point_size);
        obj->enableColorFromZ(false);
        outObj->insert(obj);
    }
    else
    {
        auto obj = opengl::CPointCloudColoured::Create();
        obj->loadFromPointsMap(this);
        obj->setPointSize(renderOptions.point_size);
        mrpt::math::TPoint3D pMin, pMax;
        this->boundingBox(pMin, pMax);
        obj->recolorizeByCoordinate(
            pMin.z, pMax.z, 2 /*z*/, renderOptions.colormap);
        outObj->insert(obj);
    }
    MRPT_END
}

float CPointsMap::compute3DMatchingRatio(
    const mrpt::maps::CMetricMap* otherMap2,
    const mrpt::poses::CPose3D& otherMapPose,
    const TMatchingRatioParams& mrp) const
{
    TMatchingPairList correspondences;
    TMatchingParams params;
    TMatchingExtraResults extraResults;

    params.maxDistForCorrespondence = mrp.maxDistForCorr;

    this->determineMatching3D(
        otherMap2->getAsSimplePointsMap(), otherMapPose, correspondences,
        params, extraResults);

    return extraResults.correspondencesRatio;
}

/*---------------------------------------------------------------
                        getLargestDistanceFromOrigin
---------------------------------------------------------------*/
float CPointsMap::getLargestDistanceFromOrigin() const
{
    // Updated?
    if (!m_largestDistanceFromOriginIsUpdated)
    {
        // NO: Update it:
        float maxDistSq = 0, d;
        for (auto X = m_x.begin(), Y = m_y.begin(), Z = m_z.begin();
             X != m_x.end(); ++X, ++Y, ++Z)
        {
            d = square(*X) + square(*Y) + square(*Z);
            maxDistSq = max(d, maxDistSq);
        }

        m_largestDistanceFromOrigin = sqrt(maxDistSq);
        m_largestDistanceFromOriginIsUpdated = true;
    }
    return m_largestDistanceFromOrigin;
}

/*---------------------------------------------------------------
                        getAllPoints
---------------------------------------------------------------*/
void CPointsMap::getAllPoints(
    vector<float>& xs, vector<float>& ys, size_t decimation) const
{
    MRPT_START
    ASSERT_(decimation > 0);
    if (decimation == 1)
    {
        xs = vector<float>(m_x.begin(), m_x.end());
        ys = vector<float>(m_y.begin(), m_y.end());
    }
    else
    {
        size_t N = m_x.size() / decimation;

        xs.resize(N);
        ys.resize(N);

        auto X = m_x.begin();
        auto Y = m_y.begin();
        for (auto oX = xs.begin(), oY = ys.begin(); oX != xs.end();
             X += decimation, Y += decimation, ++oX, ++oY)
        {
            *oX = *X;
            *oY = *Y;
        }
    }
    MRPT_END
}

/*---------------------------------------------------------------
                        squareDistanceToClosestCorrespondence
---------------------------------------------------------------*/
float CPointsMap::squareDistanceToClosestCorrespondence(
    float x0, float y0) const
{
    // Just the closest point:

#if 1
    return kdTreeClosestPoint2DsqrError(x0, y0);
#else
    // The distance to the line that interpolates the TWO closest points:
    float x1, y1, x2, y2, d1, d2;
    kdTreeTwoClosestPoint2D(
        x0, y0,  // The query
        x1, y1,  // Closest point #1
        x2, y2,  // Closest point #2
        d1, d2);

    ASSERT_(d2 >= d1);

    // If the two points are too far, do not interpolate:
    float d12 = square(x1 - x2) + square(y1 - y2);
    if (d12 > 0.20f * 0.20f || d12 < 0.03f * 0.03f)
    {
        return square(x1 - x0) + square(y1 - y0);
    }
    else
    {  // Interpolate
        double interp_x, interp_y;

        // math::closestFromPointToSegment(
        math::closestFromPointToLine(
            x0, y0,  // the point
            x1, y1, x2, y2,  // The segment
            interp_x, interp_y  // out
        );

        return square(interp_x - x0) + square(interp_y - y0);
    }
#endif
}

/*---------------------------------------------------------------
                boundingBox
---------------------------------------------------------------*/
void CPointsMap::boundingBox(
    float& min_x, float& max_x, float& min_y, float& max_y, float& min_z,
    float& max_z) const
{
    MRPT_START

    const size_t nPoints = m_x.size();

    if (!m_boundingBoxIsUpdated)
    {
        if (!nPoints)
        {
            m_bb_min_x = m_bb_max_x = m_bb_min_y = m_bb_max_y = m_bb_min_z =
                m_bb_max_z = 0;
        }
        else
        {
#if MRPT_HAS_SSE2
            // Vectorized version: ~ 9x times faster

            // Number of 4-floats:
            size_t nPackets = nPoints / 4;

            // For the bounding box:
            __m128 x_mins = _mm_set1_ps(std::numeric_limits<float>::max());
            __m128 x_maxs = _mm_set1_ps(std::numeric_limits<float>::min());
            __m128 y_mins = x_mins, y_maxs = x_maxs;
            __m128 z_mins = x_mins, z_maxs = x_maxs;

            const float* ptr_in_x = &m_x[0];
            const float* ptr_in_y = &m_y[0];
            const float* ptr_in_z = &m_z[0];

            for (; nPackets;
                 nPackets--, ptr_in_x += 4, ptr_in_y += 4, ptr_in_z += 4)
            {
                const __m128 xs = _mm_loadu_ps(ptr_in_x);  // *Unaligned* load
                x_mins = _mm_min_ps(x_mins, xs);
                x_maxs = _mm_max_ps(x_maxs, xs);

                const __m128 ys = _mm_loadu_ps(ptr_in_y);
                y_mins = _mm_min_ps(y_mins, ys);
                y_maxs = _mm_max_ps(y_maxs, ys);

                const __m128 zs = _mm_loadu_ps(ptr_in_z);
                z_mins = _mm_min_ps(z_mins, zs);
                z_maxs = _mm_max_ps(z_maxs, zs);
            }

            // Recover the min/max:
            alignas(MRPT_MAX_STATIC_ALIGN_BYTES) float temp_nums[4];

            _mm_store_ps(temp_nums, x_mins);
            m_bb_min_x =
                min(min(temp_nums[0], temp_nums[1]),
                    min(temp_nums[2], temp_nums[3]));
            _mm_store_ps(temp_nums, y_mins);
            m_bb_min_y =
                min(min(temp_nums[0], temp_nums[1]),
                    min(temp_nums[2], temp_nums[3]));
            _mm_store_ps(temp_nums, z_mins);
            m_bb_min_z =
                min(min(temp_nums[0], temp_nums[1]),
                    min(temp_nums[2], temp_nums[3]));
            _mm_store_ps(temp_nums, x_maxs);
            m_bb_max_x =
                max(max(temp_nums[0], temp_nums[1]),
                    max(temp_nums[2], temp_nums[3]));
            _mm_store_ps(temp_nums, y_maxs);
            m_bb_max_y =
                max(max(temp_nums[0], temp_nums[1]),
                    max(temp_nums[2], temp_nums[3]));
            _mm_store_ps(temp_nums, z_maxs);
            m_bb_max_z =
                max(max(temp_nums[0], temp_nums[1]),
                    max(temp_nums[2], temp_nums[3]));

            // extra
            for (size_t k = 0; k < nPoints % 4; k++)
            {
                m_bb_min_x = std::min(m_bb_min_x, ptr_in_x[k]);
                m_bb_max_x = std::max(m_bb_max_x, ptr_in_x[k]);

                m_bb_min_y = std::min(m_bb_min_y, ptr_in_y[k]);
                m_bb_max_y = std::max(m_bb_max_y, ptr_in_y[k]);

                m_bb_min_z = std::min(m_bb_min_z, ptr_in_z[k]);
                m_bb_max_z = std::max(m_bb_max_z, ptr_in_z[k]);
            }
#else
            // Non vectorized version:
            m_bb_min_x = m_bb_min_y = m_bb_min_z =
                (std::numeric_limits<float>::max)();

            m_bb_max_x = m_bb_max_y = m_bb_max_z =
                -(std::numeric_limits<float>::max)();

            for (auto xi = m_x.begin(), yi = m_y.begin(), zi = m_z.begin();
                 xi != m_x.end(); xi++, yi++, zi++)
            {
                m_bb_min_x = min(m_bb_min_x, *xi);
                m_bb_max_x = max(m_bb_max_x, *xi);
                m_bb_min_y = min(m_bb_min_y, *yi);
                m_bb_max_y = max(m_bb_max_y, *yi);
                m_bb_min_z = min(m_bb_min_z, *zi);
                m_bb_max_z = max(m_bb_max_z, *zi);
            }
#endif
        }
        m_boundingBoxIsUpdated = true;
    }

    min_x = m_bb_min_x;
    max_x = m_bb_max_x;
    min_y = m_bb_min_y;
    max_y = m_bb_max_y;
    min_z = m_bb_min_z;
    max_z = m_bb_max_z;
    MRPT_END
}

/*---------------------------------------------------------------
                computeMatchingWith3D
---------------------------------------------------------------*/
void CPointsMap::determineMatching3D(
    const mrpt::maps::CMetricMap* otherMap2, const CPose3D& otherMapPose,
    TMatchingPairList& correspondences, const TMatchingParams& params,
    TMatchingExtraResults& extraResults) const
{
    MRPT_START

    extraResults = TMatchingExtraResults();

    ASSERT_ABOVE_(params.decimation_other_map_points, 0);
    ASSERT_BELOW_(
        params.offset_other_map_points, params.decimation_other_map_points);

    ASSERT_(otherMap2->GetRuntimeClass()->derivedFrom(CLASS_ID(CPointsMap)));
    const auto* otherMap = static_cast<const CPointsMap*>(otherMap2);

    const size_t nLocalPoints = otherMap->size();
    const size_t nGlobalPoints = this->size();
    float _sumSqrDist = 0;
    size_t _sumSqrCount = 0;
    size_t nOtherMapPointsWithCorrespondence =
        0;  // Number of points with one corrs. at least

    float local_x_min = std::numeric_limits<float>::max(),
          local_x_max = -std::numeric_limits<float>::max();
    float local_y_min = std::numeric_limits<float>::max(),
          local_y_max = -std::numeric_limits<float>::max();
    float local_z_min = std::numeric_limits<float>::max(),
          local_z_max = -std::numeric_limits<float>::max();

    double maxDistForCorrespondenceSquared;

    // Prepare output: no correspondences initially:
    correspondences.clear();
    correspondences.reserve(nLocalPoints);

    TMatchingPairList _correspondences;
    _correspondences.reserve(nLocalPoints);

    // Empty maps?  Nothing to do
    if (!nGlobalPoints || !nLocalPoints) return;

    // Try to do matching only if the bounding boxes have some overlap:
    // Transform all local points:
    vector<float> x_locals(nLocalPoints), y_locals(nLocalPoints),
        z_locals(nLocalPoints);

    for (unsigned int localIdx = params.offset_other_map_points;
         localIdx < nLocalPoints;
         localIdx += params.decimation_other_map_points)
    {
        float x_local, y_local, z_local;
        otherMapPose.composePoint(
            otherMap->m_x[localIdx], otherMap->m_y[localIdx],
            otherMap->m_z[localIdx], x_local, y_local, z_local);

        x_locals[localIdx] = x_local;
        y_locals[localIdx] = y_local;
        z_locals[localIdx] = z_local;

        // Find the bounding box:
        local_x_min = min(local_x_min, x_local);
        local_x_max = max(local_x_max, x_local);
        local_y_min = min(local_y_min, y_local);
        local_y_max = max(local_y_max, y_local);
        local_z_min = min(local_z_min, z_local);
        local_z_max = max(local_z_max, z_local);
    }

    // Find the bounding box:
    float global_x_min, global_x_max, global_y_min, global_y_max, global_z_min,
        global_z_max;
    this->boundingBox(
        global_x_min, global_x_max, global_y_min, global_y_max, global_z_min,
        global_z_max);

    // Solo hacer matching si existe alguna posibilidad de que
    //  los dos mapas se toquen:
    if (local_x_min > global_x_max || local_x_max < global_x_min ||
        local_y_min > global_y_max || local_y_max < global_y_min)
        return;  // No need to compute: matching is ZERO.

    // Loop for each point in local map:
    // --------------------------------------------------
    for (unsigned int localIdx = params.offset_other_map_points;
         localIdx < nLocalPoints;
         localIdx += params.decimation_other_map_points)
    {
        // For speed-up:
        const float x_local = x_locals[localIdx];
        const float y_local = y_locals[localIdx];
        const float z_local = z_locals[localIdx];

        {
            // KD-TREE implementation
            // Use a KD-tree to look for the nearnest neighbor of:
            //   (x_local, y_local, z_local)
            // In "this" (global/reference) points map.

            float tentativ_err_sq;
            const unsigned int tentativ_this_idx = kdTreeClosestPoint3D(
                x_local, y_local, z_local,  // Look closest to this guy
                tentativ_err_sq  // save here the min. distance squared
            );

            // Compute max. allowed distance:
            maxDistForCorrespondenceSquared = square(
                params.maxAngularDistForCorrespondence *
                    params.angularDistPivotPoint.distanceTo(
                        TPoint3D(x_local, y_local, z_local)) +
                params.maxDistForCorrespondence);

            // Distance below the threshold??
            if (tentativ_err_sq < maxDistForCorrespondenceSquared)
            {
                // Save all the correspondences:
                _correspondences.resize(_correspondences.size() + 1);

                TMatchingPair& p = _correspondences.back();

                p.this_idx = tentativ_this_idx;
                p.this_x = m_x[tentativ_this_idx];
                p.this_y = m_y[tentativ_this_idx];
                p.this_z = m_z[tentativ_this_idx];

                p.other_idx = localIdx;
                p.other_x = otherMap->m_x[localIdx];
                p.other_y = otherMap->m_y[localIdx];
                p.other_z = otherMap->m_z[localIdx];

                p.errorSquareAfterTransformation = tentativ_err_sq;

                // At least one:
                nOtherMapPointsWithCorrespondence++;

                // Accumulate the MSE:
                _sumSqrDist += p.errorSquareAfterTransformation;
                _sumSqrCount++;
            }

        }  // End of test_match
    }  // For each local point

    // Additional consistency filter: "onlyKeepTheClosest" up to now
    //  led to just one correspondence for each "local map" point, but
    //  many of them may have as corresponding pair the same "global point"!!
    // -------------------------------------------------------------------------
    if (params.onlyUniqueRobust)
    {
        ASSERTMSG_(
            params.onlyKeepTheClosest,
            "ERROR: onlyKeepTheClosest must be also set to true when "
            "onlyUniqueRobust=true.");
        _correspondences.filterUniqueRobustPairs(
            nGlobalPoints, correspondences);
    }
    else
    {
        correspondences.swap(_correspondences);
    }

    // If requested, copy sum of squared distances to output pointer:
    // -------------------------------------------------------------------
    extraResults.sumSqrDist =
        (_sumSqrCount) ? _sumSqrDist / static_cast<double>(_sumSqrCount) : 0;
    extraResults.correspondencesRatio = params.decimation_other_map_points *
                                        nOtherMapPointsWithCorrespondence /
                                        d2f(nLocalPoints);

    MRPT_END
}

/*---------------------------------------------------------------
                extractCylinder
---------------------------------------------------------------*/
void CPointsMap::extractCylinder(
    const TPoint2D& center, const double radius, const double zmin,
    const double zmax, CPointsMap* outMap)
{
    outMap->clear();
    for (size_t k = 0; k < m_x.size(); k++)
    {
        if ((m_z[k] <= zmax && m_z[k] >= zmin) &&
            (sqrt(square(center.x - m_x[k]) + square(center.y - m_y[k])) <
             radius))
            outMap->insertPoint(m_x[k], m_y[k], m_z[k]);
    }
}

/*---------------------------------------------------------------
                extractPoints
---------------------------------------------------------------*/
void CPointsMap::extractPoints(
    const TPoint3D& corner1, const TPoint3D& corner2, CPointsMap* outMap,
    double R, double G, double B)
{
    outMap->clear();
    double minX, maxX, minY, maxY, minZ, maxZ;
    minX = min(corner1.x, corner2.x);
    maxX = max(corner1.x, corner2.x);
    minY = min(corner1.y, corner2.y);
    maxY = max(corner1.y, corner2.y);
    minZ = min(corner1.z, corner2.z);
    maxZ = max(corner1.z, corner2.z);
    for (size_t k = 0; k < m_x.size(); k++)
    {
        if ((m_x[k] >= minX && m_x[k] <= maxX) &&
            (m_y[k] >= minY && m_y[k] <= maxY) &&
            (m_z[k] >= minZ && m_z[k] <= maxZ))
            outMap->insertPointRGB(m_x[k], m_y[k], m_z[k], R, G, B);
    }
}

/*---------------------------------------------------------------
                compute3DDistanceToMesh
---------------------------------------------------------------*/
void CPointsMap::compute3DDistanceToMesh(
    const mrpt::maps::CMetricMap* otherMap2,
    [[maybe_unused]] const CPose3D& otherMapPose,
    float maxDistForCorrespondence, TMatchingPairList& correspondences,
    float& correspondencesRatio)
{
    MRPT_START

    const auto* otherMap = static_cast<const CPointsMap*>(otherMap2);

    const size_t nLocalPoints = otherMap->size();
    const size_t nGlobalPoints = this->size();
    size_t nOtherMapPointsWithCorrespondence =
        0;  // Number of points with one corrs. at least

    // Prepare output: no correspondences initially:
    correspondences.clear();
    correspondences.reserve(nLocalPoints);
    correspondencesRatio = 0;

    // aux correspondence vector
    TMatchingPairList _correspondences;
    _correspondences.reserve(nLocalPoints);

    // Hay mapa global?
    if (!nGlobalPoints) return;  // No

    // Hay mapa local?
    if (!nLocalPoints) return;  // No

    // we'll assume by now both reference systems are the same
    float local_x_min, local_x_max, local_y_min, local_y_max, local_z_min,
        local_z_max;
    otherMap->boundingBox(
        local_x_min, local_x_max, local_y_min, local_y_max, local_z_min,
        local_z_max);

    // Find the bounding box:
    float global_x_min, global_x_max, global_y_min, global_y_max, global_z_min,
        global_z_max;
    this->boundingBox(
        global_x_min, global_x_max, global_y_min, global_y_max, global_z_min,
        global_z_max);

    // Solo hacer matching si existe alguna posibilidad de que
    //  los dos mapas se toquen:
    if (local_x_min > global_x_max || local_x_max < global_x_min ||
        local_y_min > global_y_max || local_y_max < global_y_min)
        return;  // No hace falta hacer matching,
    //   porque es de CERO.

    std::vector<std::vector<size_t>> vIdx;

    // Loop for each point in local map:
    // --------------------------------------------------
    std::vector<float> outX, outY, outZ, tentativeErrSq;
    std::vector<size_t> outIdx;
    for (unsigned int localIdx = 0; localIdx < nLocalPoints; ++localIdx)
    {
        // For speed-up:
        const float x_local = otherMap->m_x[localIdx];
        const float y_local = otherMap->m_y[localIdx];
        const float z_local = otherMap->m_z[localIdx];

        {
            // KD-TREE implementation
            // Use a KD-tree to look for the nearnest neighbor of:
            //   (x_local, y_local, z_local)
            // In "this" (global/reference) points map.
            kdTreeNClosestPoint3DWithIdx(
                x_local, y_local, z_local,  // Look closest to this guy
                3,  // get the three closest points
                outX, outY, outZ,  // output vectors
                outIdx,  // output indexes
                tentativeErrSq  // save here the min. distance squared
            );

            // get the centroid
            const float mX = (outX[0] + outX[1] + outX[2]) / 3.0;
            const float mY = (outY[0] + outY[1] + outY[2]) / 3.0;
            const float mZ = (outZ[0] + outZ[1] + outZ[2]) / 3.0;

            const float distanceForThisPoint = fabs(mrpt::math::distance(
                TPoint3D(x_local, y_local, z_local), TPoint3D(mX, mY, mZ)));

            // Distance below the threshold??
            if (distanceForThisPoint < maxDistForCorrespondence)
            {
                // Save all the correspondences:
                _correspondences.resize(_correspondences.size() + 1);

                TMatchingPair& p = _correspondences.back();

                p.this_idx = nOtherMapPointsWithCorrespondence++;  // insert a
                // consecutive index
                // here
                p.this_x = mX;
                p.this_y = mY;
                p.this_z = mZ;

                p.other_idx = localIdx;
                p.other_x = otherMap->m_x[localIdx];
                p.other_y = otherMap->m_y[localIdx];
                p.other_z = otherMap->m_z[localIdx];

                p.errorSquareAfterTransformation = distanceForThisPoint;

                // save the indexes
                std::sort(outIdx.begin(), outIdx.end());
                vIdx.push_back(outIdx);
            }
        }  // End of test_match
    }  // For each local point

    // Additional consistency filter: "onlyKeepTheClosest" up to now
    //  led to just one correspondence for each "local map" point, but
    //  many of them may have as corresponding pair the same "global point"!!
    // -------------------------------------------------------------------------
    std::map<size_t, std::map<size_t, std::map<size_t, pair<size_t, float>>>>
        best;  // 3D associative map
    TMatchingPairList::iterator it;
    for (it = _correspondences.begin(); it != _correspondences.end(); ++it)
    {
        const size_t i0 = vIdx[it->this_idx][0];
        const size_t i1 = vIdx[it->this_idx][1];
        const size_t i2 = vIdx[it->this_idx][2];

        if (best.find(i0) != best.end() &&
            best[i0].find(i1) != best[i0].end() &&
            best[i0][i1].find(i2) !=
                best[i0][i1]
                    .end())  // if there is a match, check if it is better
        {
            if (best[i0][i1][i2].second > it->errorSquareAfterTransformation)
            {
                best[i0][i1][i2].first = it->this_idx;
                best[i0][i1][i2].second = it->errorSquareAfterTransformation;
            }
        }
        else  // if there is no match
        {
            best[i0][i1][i2].first = it->this_idx;
            best[i0][i1][i2].second = it->errorSquareAfterTransformation;
        }
    }  // end it correspondences

    for (it = _correspondences.begin(); it != _correspondences.end(); ++it)
    {
        const size_t i0 = vIdx[it->this_idx][0];
        const size_t i1 = vIdx[it->this_idx][1];
        const size_t i2 = vIdx[it->this_idx][2];

        if (best[i0][i1][i2].first == it->this_idx)
            correspondences.push_back(*it);
    }

    // The ratio of points in the other map with corrs:
    correspondencesRatio =
        nOtherMapPointsWithCorrespondence / d2f(nLocalPoints);

    MRPT_END
}

double CPointsMap::internal_computeObservationLikelihoodPointCloud3D(
    const mrpt::poses::CPose3D& pc_in_map, const float* xs, const float* ys,
    const float* zs, const std::size_t num_pts)
{
    MRPT_TRY_START

    float closest_x, closest_y, closest_z;
    float closest_err;
    const float max_sqr_err = square(likelihoodOptions.max_corr_distance);
    double sumSqrDist = 0;

    std::size_t nPtsForAverage = 0;
    for (std::size_t i = 0; i < num_pts;
         i += likelihoodOptions.decimation, nPtsForAverage++)
    {
        // Transform the point from the scan reference to its global 3D
        // position:
        float xg, yg, zg;
        pc_in_map.composePoint(xs[i], ys[i], zs[i], xg, yg, zg);

        kdTreeClosestPoint3D(
            xg, yg, zg,  // Look for the closest to this guy
            closest_x, closest_y,
            closest_z,  // save here the closest match
            closest_err  // save here the min. distance squared
        );

        // Put a limit:
        mrpt::keep_min(closest_err, max_sqr_err);

        sumSqrDist += static_cast<double>(closest_err);
    }
    if (nPtsForAverage) sumSqrDist /= nPtsForAverage;

    // Log-likelihood:
    return -sumSqrDist / likelihoodOptions.sigma_dist;

    MRPT_TRY_END
}

double CPointsMap::internal_computeObservationLikelihood(
    const CObservation& obs, const CPose3D& takenFrom)
{
    // This function depends on the observation type:
    // -----------------------------------------------------
    if (IS_CLASS(obs, CObservation2DRangeScan))
    {
        // Observation is a laser range scan:
        // -------------------------------------------
        const auto& o = static_cast<const CObservation2DRangeScan&>(obs);

        // Build (if not done before) the points map representation of this
        // observation:
        const auto* scanPoints = o.buildAuxPointsMap<CPointsMap>();

        const size_t N = scanPoints->m_x.size();
        if (!N || !this->size()) return -100;

        const float* xs = &scanPoints->m_x[0];
        const float* ys = &scanPoints->m_y[0];
        const float* zs = &scanPoints->m_z[0];

        if (takenFrom.isHorizontal())
        {
            double sumSqrDist = 0;
            float closest_x, closest_y;
            float closest_err;
            const float max_sqr_err =
                square(likelihoodOptions.max_corr_distance);

            // optimized 2D version ---------------------------
            TPose2D takenFrom2D = CPose2D(takenFrom).asTPose();

            const double ccos = cos(takenFrom2D.phi);
            const double csin = sin(takenFrom2D.phi);
            int nPtsForAverage = 0;

            for (size_t i = 0; i < N;
                 i += likelihoodOptions.decimation, nPtsForAverage++)
            {
                // Transform the point from the scan reference to its global
                // 3D position:
                const float xg = takenFrom2D.x + ccos * xs[i] - csin * ys[i];
                const float yg = takenFrom2D.y + csin * xs[i] + ccos * ys[i];

                kdTreeClosestPoint2D(
                    xg, yg,  // Look for the closest to this guy
                    closest_x, closest_y,  // save here the closest match
                    closest_err  // save here the min. distance squared
                );

                // Put a limit:
                mrpt::keep_min(closest_err, max_sqr_err);

                sumSqrDist += static_cast<double>(closest_err);
            }
            sumSqrDist /= nPtsForAverage;
            // Log-likelihood:
            return -sumSqrDist / likelihoodOptions.sigma_dist;
        }
        else
        {
            // Generic 3D version ---------------------------
            return internal_computeObservationLikelihoodPointCloud3D(
                takenFrom, xs, ys, zs, N);
        }
    }
    else if (IS_CLASS(obs, CObservationVelodyneScan))
    {
        const auto& o = dynamic_cast<const CObservationVelodyneScan&>(obs);

        // Automatically generate pointcloud if needed:
        if (!o.point_cloud.size())
            const_cast<CObservationVelodyneScan&>(o).generatePointCloud();

        const size_t N = o.point_cloud.size();
        if (!N || !this->size()) return -100;

        const CPose3D sensorAbsPose = takenFrom + o.sensorPose;

        const float* xs = &o.point_cloud.x[0];
        const float* ys = &o.point_cloud.y[0];
        const float* zs = &o.point_cloud.z[0];

        return internal_computeObservationLikelihoodPointCloud3D(
            sensorAbsPose, xs, ys, zs, N);
    }
    else if (IS_CLASS(obs, CObservationPointCloud))
    {
        const auto& o = dynamic_cast<const CObservationPointCloud&>(obs);

        const size_t N = o.pointcloud->size();
        if (!N || !this->size()) return -100;

        const CPose3D sensorAbsPose = takenFrom + o.sensorPose;

        auto xs = o.pointcloud->getPointsBufferRef_x();
        auto ys = o.pointcloud->getPointsBufferRef_y();
        auto zs = o.pointcloud->getPointsBufferRef_z();

        return internal_computeObservationLikelihoodPointCloud3D(
            sensorAbsPose, &xs[0], &ys[0], &zs[0], N);
    }

    return .0;
}

namespace mrpt::obs
{
// Tricky way to call to a library that depends on us, a sort of "run-time"
// linking: ptr_internal_build_points_map_from_scan2D is a functor in
// "mrpt-obs", set by "mrpt-maps" at its startup.
using scan2pts_functor = void (*)(
    const mrpt::obs::CObservation2DRangeScan& obs,
    mrpt::maps::CMetricMap::Ptr& out_map, const void* insertOps);

extern void internal_set_build_points_map_from_scan2D(scan2pts_functor fn);
}  // namespace mrpt::obs

void internal_build_points_map_from_scan2D(
    const mrpt::obs::CObservation2DRangeScan& obs,
    mrpt::maps::CMetricMap::Ptr& out_map, const void* insertOps)
{
    // Create on first call:
    if (out_map) return;  // Already done!

    out_map = std::make_shared<CSimplePointsMap>();

    if (insertOps)
        static_cast<CSimplePointsMap*>(out_map.get())->insertionOptions =
            *static_cast<const CPointsMap::TInsertionOptions*>(insertOps);

    out_map->insertObservation(obs, nullptr);
}

struct TAuxLoadFunctor
{
    TAuxLoadFunctor()
    {
        mrpt::obs::internal_set_build_points_map_from_scan2D(
            &internal_build_points_map_from_scan2D);
    }
};

// used just to set "ptr_internal_build_points_map_from_scan2D"
static TAuxLoadFunctor dummy_loader;

// ================================ PLY files import & export virtual
// methods
// ================================

/** In a base class, will be called after PLY_import_set_vertex_count() once
 * for each loaded point. \param pt_color Will be nullptr if the loaded file
 * does not provide color info.
 */
void CPointsMap::PLY_import_set_vertex(
    const size_t idx, const mrpt::math::TPoint3Df& pt,
    [[maybe_unused]] const mrpt::img::TColorf* pt_color)
{
    this->setPoint(idx, pt.x, pt.y, pt.z);
}

/** In a base class, return the number of vertices */
size_t CPointsMap::PLY_export_get_vertex_count() const { return this->size(); }
/** In a base class, will be called after PLY_export_get_vertex_count() once
 * for each exported point. \param pt_color Will be nullptr if the loaded
 * file does not provide color info.
 */
void CPointsMap::PLY_export_get_vertex(
    const size_t idx, mrpt::math::TPoint3Df& pt, bool& pt_has_color,
    [[maybe_unused]] mrpt::img::TColorf& pt_color) const
{
    pt_has_color = false;

    pt.x = m_x[idx];
    pt.y = m_y[idx];
    pt.z = m_z[idx];
}

// Generic implementation (a more optimized one should exist in derived
// classes):
void CPointsMap::addFrom(const CPointsMap& anotherMap)
{
    const size_t nThis = this->size();
    const size_t nOther = anotherMap.size();

    const size_t nTot = nThis + nOther;

    this->resize(nTot);

    for (size_t i = 0, j = nThis; i < nOther; i++, j++)
    {
        m_x[j] = anotherMap.m_x[i];
        m_y[j] = anotherMap.m_y[i];
        m_z[j] = anotherMap.m_z[i];
    }

    // Also copy other data fields (color, ...)
    addFrom_classSpecific(anotherMap, nThis);

    mark_as_modified();
}

/*---------------------------------------------------------------
                        applyDeletionMask
 ---------------------------------------------------------------*/
void CPointsMap::applyDeletionMask(const std::vector<bool>& mask)
{
    ASSERT_EQUAL_(size(), mask.size());
    // Remove marked points:
    const size_t n = mask.size();
    vector<float> Pt;
    size_t i, j;
    for (i = 0, j = 0; i < n; i++)
    {
        if (!mask[i])
        {
            // Pt[j] <---- Pt[i]
            this->getPointAllFieldsFast(i, Pt);
            this->setPointAllFieldsFast(j++, Pt);
        }
    }

    // Set new correct size:
    this->resize(j);

    mark_as_modified();
}

/*---------------------------------------------------------------
                    insertAnotherMap
 ---------------------------------------------------------------*/
void CPointsMap::insertAnotherMap(
    const CPointsMap* otherMap, const CPose3D& otherPose)
{
    const size_t N_this = size();
    const size_t N_other = otherMap->size();

    // Set the new size:
    this->resize(N_this + N_other);

    mrpt::math::TPoint3Df pt;
    size_t src, dst;
    for (src = 0, dst = N_this; src < N_other; src++, dst++)
    {
        // Load the next point:
        otherMap->getPointFast(src, pt.x, pt.y, pt.z);

        // Translation:
        double gx, gy, gz;
        otherPose.composePoint(pt.x, pt.y, pt.z, gx, gy, gz);

        // Add to this map:
        this->setPointFast(dst, gx, gy, gz);
    }

    // Also copy other data fields (color, ...)
    addFrom_classSpecific(*otherMap, N_this);

    mark_as_modified();
}

/** Helper method for ::copyFrom() */
void CPointsMap::base_copyFrom(const CPointsMap& obj)
{
    MRPT_START

    if (this == &obj) return;

    m_x = obj.m_x;
    m_y = obj.m_y;
    m_z = obj.m_z;

    m_largestDistanceFromOriginIsUpdated =
        obj.m_largestDistanceFromOriginIsUpdated;
    m_largestDistanceFromOrigin = obj.m_largestDistanceFromOrigin;

    // Fill missing fields (R,G,B,min_dist) with default values.
    this->resize(m_x.size());

    kdtree_mark_as_outdated();

    MRPT_END
}

/*---------------------------------------------------------------
                    internal_insertObservation

  Insert the observation information into this map.
 ---------------------------------------------------------------*/
bool CPointsMap::internal_insertObservation(
    const CObservation& obs, const CPose3D* robotPose)
{
    MRPT_START

    CPose2D robotPose2D;
    CPose3D robotPose3D;

    if (robotPose)
    {
        robotPose2D = CPose2D(*robotPose);
        robotPose3D = (*robotPose);
    }
    else
    {
        // Default values are (0,0,0)
    }

    if (IS_CLASS(obs, CObservation2DRangeScan))
    {
        /********************************************************************
                    OBSERVATION TYPE: CObservation2DRangeScan
         ********************************************************************/
        mark_as_modified();

        const auto& o = static_cast<const CObservation2DRangeScan&>(obs);
        // Insert only HORIZONTAL scans??
        bool reallyInsertIt;

        if (insertionOptions.isPlanarMap)
            reallyInsertIt =
                o.isPlanarScan(insertionOptions.horizontalTolerance);
        else
            reallyInsertIt = true;

        if (reallyInsertIt)
        {
            std::vector<bool> checkForDeletion;

            // 1) Fuse into the points map or add directly?
            // ----------------------------------------------
            if (insertionOptions.fuseWithExisting)
            {
                CSimplePointsMap auxMap;
                // Fuse:
                auxMap.insertionOptions = insertionOptions;
                auxMap.insertionOptions.addToExistingPointsMap = false;

                auxMap.loadFromRangeScan(
                    o,  // The laser range scan observation
                    &robotPose3D  // The robot pose
                );

                fuseWith(
                    &auxMap,  // Fuse with this map
                    insertionOptions.minDistBetweenLaserPoints,  // Min dist.
                    &checkForDeletion  // Set to "false" if a point in "map"
                                       // has
                    // been fused.
                );

                if (!insertionOptions.disableDeletion)
                {
                    // 2) Delete points in newly added free
                    //      region, thus dynamic areas:
                    // --------------------------------------
                    // Load scan as a polygon:
                    CPolygon pol;
                    const float *xs, *ys, *zs;
                    size_t n;
                    auxMap.getPointsBuffer(n, xs, ys, zs);
                    pol.setAllVertices(n, xs, ys);

                    // Check for deletion of points in "map"
                    n = size();
                    for (size_t i = 0; i < n; i++)
                    {
                        if (checkForDeletion[i])  // Default to true, unless
                                                  // a
                        // fused point, which must be
                        // kept.
                        {
                            float x, y;
                            getPoint(i, x, y);
                            if (!pol.PointIntoPolygon(x, y))
                                checkForDeletion[i] =
                                    false;  // Out of polygon, don't delete
                        }
                    }

                    // Create a new points list just with non-deleted
                    // points.
                    // ----------------------------------------------------------
                    applyDeletionMask(checkForDeletion);
                }
            }
            else
            {
                // Don't fuse: Simply add
                insertionOptions.addToExistingPointsMap = true;
                loadFromRangeScan(
                    o,  // The laser range scan observation
                    &robotPose3D  // The robot pose
                );
            }

            return true;
        }
        // A planar map and a non-horizontal scan.
        else
            return false;
    }
    else if (IS_CLASS(obs, CObservation3DRangeScan))
    {
        /********************************************************************
                    OBSERVATION TYPE: CObservation3DRangeScan
         ********************************************************************/
        mark_as_modified();

        const auto& o = static_cast<const CObservation3DRangeScan&>(obs);
        // Insert only HORIZONTAL scans??
        bool reallyInsertIt;

        if (insertionOptions.isPlanarMap)
            reallyInsertIt =
                false;  // Don't insert 3D range observation into planar map
        else
            reallyInsertIt = true;

        if (reallyInsertIt)
        {
            // 1) Fuse into the points map or add directly?
            // ----------------------------------------------
            if (insertionOptions.fuseWithExisting)
            {
                // Fuse:
                CSimplePointsMap auxMap;
                auxMap.insertionOptions = insertionOptions;
                auxMap.insertionOptions.addToExistingPointsMap = false;

                auxMap.loadFromRangeScan(
                    o,  // The laser range scan observation
                    &robotPose3D  // The robot pose
                );

                fuseWith(
                    &auxMap,  // Fuse with this map
                    insertionOptions.minDistBetweenLaserPoints,  // Min dist.
                    nullptr  // rather than &checkForDeletion which we don't
                    // need
                    // for 3D observations
                );
            }
            else
            {
                // Don't fuse: Simply add
                insertionOptions.addToExistingPointsMap = true;
                loadFromRangeScan(
                    o,  // The laser range scan observation
                    &robotPose3D  // The robot pose
                );
            }

            return true;
        }
        // A planar map and a non-horizontal scan.
        else
            return false;
    }
    else if (IS_CLASS(obs, CObservationRange))
    {
        /********************************************************************
                    OBSERVATION TYPE: CObservationRange  (IRs, Sonars, etc.)
         ********************************************************************/
        mark_as_modified();

        const auto& o = static_cast<const CObservationRange&>(obs);

        const double aper_2 = 0.5 * o.sensorConeApperture;

        this->reserve(
            this->size() + o.sensedData.size() * 30);  // faster push_back's.

        for (auto it = o.begin(); it != o.end(); ++it)
        {
            const CPose3D sensorPose = robotPose3D + CPose3D(it->sensorPose);
            const double rang = it->sensedDistance;

            if (rang <= 0 || rang < o.minSensorDistance ||
                rang > o.maxSensorDistance)
                continue;

            // Insert a few points with a given maximum separation between
            // them:
            const double arc_len = o.sensorConeApperture * rang;
            const unsigned int nSteps = round(1 + arc_len / 0.05);
            const double Aa = o.sensorConeApperture / double(nSteps);
            TPoint3D loc, glob;

            for (double a1 = -aper_2; a1 < aper_2; a1 += Aa)
            {
                for (double a2 = -aper_2; a2 < aper_2; a2 += Aa)
                {
                    loc.x = cos(a1) * cos(a2) * rang;
                    loc.y = cos(a1) * sin(a2) * rang;
                    loc.z = sin(a1) * rang;
                    sensorPose.composePoint(loc, glob);

                    this->insertPointFast(glob.x, glob.y, glob.z);
                }
            }
        }
        return true;
    }
    else if (IS_CLASS(obs, CObservationVelodyneScan))
    {
        /********************************************************************
                    OBSERVATION TYPE: CObservationVelodyneScan
         ********************************************************************/
        mark_as_modified();

        const auto& o = static_cast<const CObservationVelodyneScan&>(obs);

        // Automatically generate pointcloud if needed:
        if (!o.point_cloud.size())
            const_cast<CObservationVelodyneScan&>(o).generatePointCloud();

        if (insertionOptions.fuseWithExisting)
        {
            // Fuse:
            CSimplePointsMap auxMap;
            auxMap.insertionOptions = insertionOptions;
            auxMap.insertionOptions.addToExistingPointsMap = false;
            auxMap.loadFromVelodyneScan(o, &robotPose3D);
            fuseWith(
                &auxMap, insertionOptions.minDistBetweenLaserPoints, nullptr /* rather than &checkForDeletion which we don't need for 3D observations */);
        }
        else
        {
            // Don't fuse: Simply add
            insertionOptions.addToExistingPointsMap = true;
            loadFromVelodyneScan(o, &robotPose3D);
        }
        return true;
    }
    else if (IS_CLASS(obs, CObservationPointCloud))
    {
        mark_as_modified();

        const auto& o = static_cast<const CObservationPointCloud&>(obs);
        ASSERT_(o.pointcloud);

        if (insertionOptions.fuseWithExisting)
        {
            fuseWith(
                o.pointcloud.get(), insertionOptions.minDistBetweenLaserPoints, nullptr /* rather than &checkForDeletion which we don't need for 3D observations */);
        }
        else
        {
            // Don't fuse: Simply add
            insertionOptions.addToExistingPointsMap = true;
            this->insertAnotherMap(o.pointcloud.get(), o.sensorPose);
        }
        return true;
    }
    else
    {
        /********************************************************************
                    OBSERVATION TYPE: Unknown
        ********************************************************************/
        return false;
    }

    MRPT_END
}

/*---------------------------------------------------------------
Insert the contents of another map into this one, fusing the previous
content with the new one. This means that points very close to existing ones
will be "fused", rather than "added". This prevents the unbounded increase
in size of these class of maps.
 ---------------------------------------------------------------*/
void CPointsMap::fuseWith(
    CPointsMap* otherMap, float minDistForFuse,
    std::vector<bool>* notFusedPoints)
{
    TMatchingPairList correspondences;
    TPoint3D a, b;
    const CPose2D nullPose(0, 0, 0);

    mark_as_modified();

    // const size_t nThis  =     this->size();
    const size_t nOther = otherMap->size();

    // Find correspondences between this map and the other one:
    // ------------------------------------------------------------
    TMatchingParams params;
    TMatchingExtraResults extraResults;

    params.maxAngularDistForCorrespondence = 0;
    params.maxDistForCorrespondence = minDistForFuse;

    determineMatching2D(
        otherMap,  // The other map
        nullPose,  // The other map's pose
        correspondences, params, extraResults);

    // Initially, all set to "true" -> "not fused".
    if (notFusedPoints)
    {
        notFusedPoints->clear();
        notFusedPoints->reserve(m_x.size() + nOther);
        notFusedPoints->resize(m_x.size(), true);
    }

    // Speeds-up possible memory reallocations:
    reserve(m_x.size() + nOther);

    // Merge matched points from both maps:
    //  AND add new points which have been not matched:
    // -------------------------------------------------
    for (size_t i = 0; i < nOther; i++)
    {
        otherMap->getPoint(i, a);  // Get "local" point into "a"
        const unsigned long w_a = otherMap->getPointWeight(i);

        // Find closest correspondence of "a":
        int closestCorr = -1;
        float minDist = std::numeric_limits<float>::max();
        for (auto corrsIt = correspondences.begin();
             corrsIt != correspondences.end(); ++corrsIt)
        {
            if (corrsIt->other_idx == i)
            {
                float dist = square(corrsIt->other_x - corrsIt->this_x) +
                             square(corrsIt->other_y - corrsIt->this_y) +
                             square(corrsIt->other_z - corrsIt->this_z);
                if (dist < minDist)
                {
                    minDist = dist;
                    closestCorr = corrsIt->this_idx;
                }
            }
        }  // End of for each correspondence...

        if (closestCorr != -1)
        {  // Merge:        FUSION
            getPoint(closestCorr, b);
            unsigned long w_b = getPointWeight(closestCorr);

            ASSERT_((w_a + w_b) > 0);

            const float F = 1.0f / (w_a + w_b);

            m_x[closestCorr] = F * (w_a * a.x + w_b * b.x);
            m_y[closestCorr] = F * (w_a * a.y + w_b * b.y);
            m_z[closestCorr] = F * (w_a * a.z + w_b * b.z);

            this->setPointWeight(closestCorr, w_a + w_b);

            // Append to fused points list
            if (notFusedPoints) (*notFusedPoints)[closestCorr] = false;
        }
        else
        {  // New point:    ADDITION
            this->insertPointFast(a.x, a.y, a.z);
            if (notFusedPoints) (*notFusedPoints).push_back(false);
        }
    }
}

void CPointsMap::loadFromVelodyneScan(
    const mrpt::obs::CObservationVelodyneScan& scan,
    const mrpt::poses::CPose3D* robotPose)
{
    ASSERT_EQUAL_(scan.point_cloud.x.size(), scan.point_cloud.y.size());
    ASSERT_EQUAL_(scan.point_cloud.x.size(), scan.point_cloud.z.size());
    ASSERT_EQUAL_(scan.point_cloud.x.size(), scan.point_cloud.intensity.size());

    if (scan.point_cloud.x.empty()) return;

    this->mark_as_modified();

    // Insert vs. load and replace:
    if (!insertionOptions.addToExistingPointsMap)
        resize(0);  // Resize to 0 instead of clear() so the std::vector<>
    // memory is not actually deallocated and can be reused.

    // Alloc space:
    const size_t nOldPtsCount = this->size();
    const size_t nScanPts = scan.point_cloud.size();
    const size_t nNewPtsCount = nOldPtsCount + nScanPts;
    this->resize(nNewPtsCount);

    const float K = 1.0f / 255;  // Intensity scale.

    // global 3D pose:
    CPose3D sensorGlobalPose;
    if (robotPose)
        sensorGlobalPose = *robotPose + scan.sensorPose;
    else
        sensorGlobalPose = scan.sensorPose;

    mrpt::math::CMatrixDouble44 HM;
    sensorGlobalPose.getHomogeneousMatrix(HM);

    const double m00 = HM(0, 0), m01 = HM(0, 1), m02 = HM(0, 2), m03 = HM(0, 3);
    const double m10 = HM(1, 0), m11 = HM(1, 1), m12 = HM(1, 2), m13 = HM(1, 3);
    const double m20 = HM(2, 0), m21 = HM(2, 1), m22 = HM(2, 2), m23 = HM(2, 3);

    // Copy points:
    for (size_t i = 0; i < nScanPts; i++)
    {
        const float inten = scan.point_cloud.intensity[i] * K;
        const double lx = scan.point_cloud.x[i];
        const double ly = scan.point_cloud.y[i];
        const double lz = scan.point_cloud.z[i];

        const double gx = m00 * lx + m01 * ly + m02 * lz + m03;
        const double gy = m10 * lx + m11 * ly + m12 * lz + m13;
        const double gz = m20 * lx + m21 * ly + m22 * lz + m23;

        this->setPointRGB(
            nOldPtsCount + i, gx, gy, gz,  // XYZ
            inten, inten, inten  // RGB
        );
    }
}