COccupancyGridMap2D_likelihood.cpp

Go to the documentation of this file.

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, 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 |
   +------------------------------------------------------------------------+ */
 
#include "maps-precomp.h"  // Precomp header
 
#include <mrpt/maps/COccupancyGridMap2D.h>
#include <mrpt/obs/CObservation2DRangeScan.h>
#include <mrpt/obs/CObservationRange.h>
#include <mrpt/maps/CSimplePointsMap.h>
#include <mrpt/utils/CStream.h>
 
using namespace mrpt;
using namespace mrpt::math;
using namespace mrpt::maps;
using namespace mrpt::obs;
using namespace mrpt::utils;
using namespace mrpt::poses;
using namespace std;
 
/*---------------------------------------------------------------
 Computes the likelihood that a given observation was taken from a given pose in
 the world being modeled with this map.
        takenFrom The robot's pose the observation is supposed to be taken from.
        obs The observation.
 This method returns a likelihood in the range [0,1].
 ---------------------------------------------------------------*/
double COccupancyGridMap2D::internal_computeObservationLikelihood(
        const CObservation* obs, const CPose3D& takenFrom3D)
{
        // Ignore laser scans if they are not planar or they are not
        //  at the altitude of this grid map:
        if (obs->GetRuntimeClass() == CLASS_ID(CObservation2DRangeScan))
        {
                const CObservation2DRangeScan* scan =
                        static_cast<const CObservation2DRangeScan*>(obs);
                if (!scan->isPlanarScan(insertionOptions.horizontalTolerance))
                        return -10;
                if (insertionOptions.useMapAltitude &&
                        fabs(insertionOptions.mapAltitude - scan->sensorPose.z()) > 0.01)
                        return -10;
 
                // OK, go on...
        }
 
        // Execute according to the selected method:
        // --------------------------------------------
        CPose2D takenFrom =
                CPose2D(takenFrom3D);  // 3D -> 2D, we are in a gridmap...
 
        switch (likelihoodOptions.likelihoodMethod)
        {
                default:
                case lmRayTracing:
                        return computeObservationLikelihood_rayTracing(obs, takenFrom);
 
                case lmMeanInformation:
                        return computeObservationLikelihood_MI(obs, takenFrom);
 
                case lmConsensus:
                        return computeObservationLikelihood_Consensus(obs, takenFrom);
 
                case lmCellsDifference:
                        return computeObservationLikelihood_CellsDifference(obs, takenFrom);
 
                case lmLikelihoodField_Thrun:
                        return computeObservationLikelihood_likelihoodField_Thrun(
                                obs, takenFrom);
 
                case lmLikelihoodField_II:
                        return computeObservationLikelihood_likelihoodField_II(
                                obs, takenFrom);
 
                case lmConsensusOWA:
                        return computeObservationLikelihood_ConsensusOWA(obs, takenFrom);
        };
}
 
/*---------------------------------------------------------------
                        computeObservationLikelihood_Consensus
---------------------------------------------------------------*/
double COccupancyGridMap2D::computeObservationLikelihood_Consensus(
        const CObservation* obs, const CPose2D& takenFrom)
{
        double likResult = 0;
 
        // This function depends on the observation type:
        // -----------------------------------------------------
        if (obs->GetRuntimeClass() != CLASS_ID(CObservation2DRangeScan))
        {
                // THROW_EXCEPTION("This method is defined for 'CObservation2DRangeScan'
                // classes only.");
                return 1e-3;
        }
        // Observation is a laser range scan:
        // -------------------------------------------
        const CObservation2DRangeScan* o =
                static_cast<const CObservation2DRangeScan*>(obs);
 
        // Insert only HORIZONTAL scans, since the grid is supposed to
        //  be a horizontal representation of space.
        if (!o->isPlanarScan(insertionOptions.horizontalTolerance))
                return 0.5f;  // NO WAY TO ESTIMATE NON HORIZONTAL SCANS!!
 
        // Assure we have a 2D points-map representation of the points from the
        // scan:
        const CPointsMap* compareMap =
                o->buildAuxPointsMap<mrpt::maps::CPointsMap>();
 
        // Observation is a points map:
        // -------------------------------------------
        size_t Denom = 0;
        //      int                     Acells = 1;
        TPoint2D pointGlobal, pointLocal;
 
        // Get the points buffers:
 
        //      compareMap.getPointsBuffer( n, xs, ys, zs );
        const size_t n = compareMap->size();
 
        for (size_t i = 0; i < n; i += likelihoodOptions.consensus_takeEachRange)
        {
                // Get the point and pass it to global coordinates:
                compareMap->getPoint(i, pointLocal);
                takenFrom.composePoint(pointLocal, pointGlobal);
 
                int cx0 = x2idx(pointGlobal.x);
                int cy0 = y2idx(pointGlobal.y);
 
                likResult += 1 - getCell_nocheck(cx0, cy0);
                Denom++;
        }
        if (Denom) likResult /= Denom;
        likResult =
                pow(likResult, static_cast<double>(likelihoodOptions.consensus_pow));
 
        return log(likResult);
}
 
/*---------------------------------------------------------------
                        computeObservationLikelihood_ConsensusOWA
---------------------------------------------------------------*/
double COccupancyGridMap2D::computeObservationLikelihood_ConsensusOWA(
        const CObservation* obs, const CPose2D& takenFrom)
{
        double likResult = 0;
 
        // This function depends on the observation type:
        // -----------------------------------------------------
        if (obs->GetRuntimeClass() == CLASS_ID(CObservation2DRangeScan))
        {
                // THROW_EXCEPTION("This method is defined for 'CObservation2DRangeScan'
                // classes only.");
                return 1e-3;
        }
        // Observation is a laser range scan:
        // -------------------------------------------
        const CObservation2DRangeScan* o =
                static_cast<const CObservation2DRangeScan*>(obs);
 
        // Insert only HORIZONTAL scans, since the grid is supposed to
        //  be a horizontal representation of space.
        if (!o->isPlanarScan(insertionOptions.horizontalTolerance))
                return 0.5;  // NO WAY TO ESTIMATE NON HORIZONTAL SCANS!!
 
        // Assure we have a 2D points-map representation of the points from the
        // scan:
        CPointsMap::TInsertionOptions insOpt;
        insOpt.minDistBetweenLaserPoints = -1;  // ALL the laser points
 
        const CPointsMap* compareMap =
                o->buildAuxPointsMap<mrpt::maps::CPointsMap>(&insOpt);
 
        // Observation is a points map:
        // -------------------------------------------
        int Acells = 1;
        TPoint2D pointGlobal, pointLocal;
 
        // Get the points buffers:
        const size_t n = compareMap->size();
 
        // Store the likelihood values in this vector:
        likelihoodOutputs.OWA_pairList.clear();
        for (size_t i = 0; i < n; i++)
        {
                // Get the point and pass it to global coordinates:
                compareMap->getPoint(i, pointLocal);
                takenFrom.composePoint(pointLocal, pointGlobal);
 
                int cx0 = x2idx(pointGlobal.x);
                int cy0 = y2idx(pointGlobal.y);
 
                int cxMin = max(0, cx0 - Acells);
                int cxMax = min(static_cast<int>(size_x) - 1, cx0 + Acells);
                int cyMin = max(0, cy0 - Acells);
                int cyMax = min(static_cast<int>(size_y) - 1, cy0 + Acells);
 
                double lik = 0;
 
                for (int cx = cxMin; cx <= cxMax; cx++)
                        for (int cy = cyMin; cy <= cyMax; cy++)
                                lik += 1 - getCell_nocheck(cx, cy);
 
                int nCells = (cxMax - cxMin + 1) * (cyMax - cyMin + 1);
                ASSERT_(nCells > 0);
                lik /= nCells;
 
                TPairLikelihoodIndex element;
                element.first = lik;
                element.second = pointGlobal;
                likelihoodOutputs.OWA_pairList.push_back(element);
        }  // for each range point
 
        // Sort the list of likelihood values, in descending order:
        // ------------------------------------------------------------
        std::sort(
                likelihoodOutputs.OWA_pairList.begin(),
                likelihoodOutputs.OWA_pairList.end());
 
        // Cut the vector to the highest "likelihoodOutputs.OWA_length" elements:
        size_t M = likelihoodOptions.OWA_weights.size();
        ASSERT_(likelihoodOutputs.OWA_pairList.size() >= M);
 
        likelihoodOutputs.OWA_pairList.resize(M);
        likelihoodOutputs.OWA_individualLikValues.resize(M);
        likResult = 0;
        for (size_t k = 0; k < M; k++)
        {
                likelihoodOutputs.OWA_individualLikValues[k] =
                        likelihoodOutputs.OWA_pairList[k].first;
                likResult += likelihoodOptions.OWA_weights[k] *
                                         likelihoodOutputs.OWA_individualLikValues[k];
        }
 
        return log(likResult);
}
 
/*---------------------------------------------------------------
                        computeObservationLikelihood_CellsDifference
---------------------------------------------------------------*/
double COccupancyGridMap2D::computeObservationLikelihood_CellsDifference(
        const CObservation* obs, const CPose2D& takenFrom)
{
        double ret = 0.5;
 
        // This function depends on the observation type:
        // -----------------------------------------------------
        if (obs->GetRuntimeClass() == CLASS_ID(CObservation2DRangeScan))
        {
                // Observation is a laser range scan:
                // -------------------------------------------
                const CObservation2DRangeScan* o =
                        static_cast<const CObservation2DRangeScan*>(obs);
 
                // Insert only HORIZONTAL scans, since the grid is supposed to
                //  be a horizontal representation of space.
                if (!o->isPlanarScan(insertionOptions.horizontalTolerance))
                        return 0.5;  // NO WAY TO ESTIMATE NON HORIZONTAL SCANS!!
 
                // Build a copy of this occupancy grid:
                COccupancyGridMap2D compareGrid(
                        takenFrom.x() - 10, takenFrom.x() + 10, takenFrom.y() - 10,
                        takenFrom.y() + 10, resolution);
                CPose3D robotPose(takenFrom);
                int Ax, Ay;
 
                // Insert in this temporary grid:
                compareGrid.insertionOptions.maxDistanceInsertion =
                        insertionOptions.maxDistanceInsertion;
                compareGrid.insertionOptions.maxOccupancyUpdateCertainty = 0.95f;
                o->insertObservationInto(&compareGrid, &robotPose);
 
                // Save Cells offset between the two grids:
                Ax = round((x_min - compareGrid.x_min) / resolution);
                Ay = round((y_min - compareGrid.y_min) / resolution);
 
                int nCellsCompared = 0;
                float cellsDifference = 0;
                int x0 = max(0, Ax);
                int y0 = max(0, Ay);
                int x1 = min(compareGrid.size_x, size_x + Ax);
                int y1 = min(compareGrid.size_y, size_y + Ay);
 
                for (int x = x0; x < x1; x += 1)
                {
                        for (int y = y0; y < y1; y += 1)
                        {
                                float xx = compareGrid.idx2x(x);
                                float yy = compareGrid.idx2y(y);
 
                                float c1 = getPos(xx, yy);
                                float c2 = compareGrid.getCell(x, y);
                                if (c2 < 0.45f || c2 > 0.55f)
                                {
                                        nCellsCompared++;
                                        if ((c1 > 0.5 && c2 < 0.5) || (c1 < 0.5 && c2 > 0.5))
                                                cellsDifference++;
                                }
                        }
                }
                ret = 1 - cellsDifference / (nCellsCompared);
        }
        return log(ret);
}
 
/*---------------------------------------------------------------
                        computeObservationLikelihood_MI
---------------------------------------------------------------*/
double COccupancyGridMap2D::computeObservationLikelihood_MI(
        const CObservation* obs, const CPose2D& takenFrom)
{
        MRPT_START
 
        CPose3D poseRobot(takenFrom);
        double res;
 
        // Dont modify the grid, only count the changes in Information
        updateInfoChangeOnly.enabled = true;
        insertionOptions.maxDistanceInsertion *=
                likelihoodOptions.MI_ratio_max_distance;
 
        // Reset the new information counters:
        updateInfoChangeOnly.cellsUpdated = 0;
        updateInfoChangeOnly.I_change = 0;
        updateInfoChangeOnly.laserRaysSkip = likelihoodOptions.MI_skip_rays;
 
        // Insert the observation (It will not be really inserted, only the
        // information counted)
        insertObservation(obs, &poseRobot);
 
        // Compute the change in I aported by the observation:
        double newObservation_mean_I;
        if (updateInfoChangeOnly.cellsUpdated)
                newObservation_mean_I =
                        updateInfoChangeOnly.I_change / updateInfoChangeOnly.cellsUpdated;
        else
                newObservation_mean_I = 0;
 
        // Let the normal mode enabled, i.e. the grid can be updated
        updateInfoChangeOnly.enabled = false;
        insertionOptions.maxDistanceInsertion /=
                likelihoodOptions.MI_ratio_max_distance;
 
        res =
                pow(newObservation_mean_I,
                        static_cast<double>(likelihoodOptions.MI_exponent));
 
        return log(res);
 
        MRPT_END
}
 
double COccupancyGridMap2D::computeObservationLikelihood_rayTracing(
        const CObservation* obs, const CPose2D& takenFrom)
{
        double ret = 0;
 
        // This function depends on the observation type:
        // -----------------------------------------------------
        if (obs->GetRuntimeClass() == CLASS_ID(CObservation2DRangeScan))
        {
                // Observation is a laser range scan:
                // -------------------------------------------
                const CObservation2DRangeScan* o =
                        static_cast<const CObservation2DRangeScan*>(obs);
                CObservation2DRangeScan simulatedObs;
 
                // Insert only HORIZONTAL scans, since the grid is supposed to
                //  be a horizontal representation of space.
                if (!o->isPlanarScan(insertionOptions.horizontalTolerance))
                        return 0.5;  // NO WAY TO ESTIMATE NON HORIZONTAL SCANS!!
 
                // The number of simulated rays will be original range scan rays /
                // DOWNRATIO
                int decimation = likelihoodOptions.rayTracing_decimation;
                int nRays = o->scan.size();
 
                // Perform simulation using same parameters than real observation:
                simulatedObs.aperture = o->aperture;
                simulatedObs.maxRange = o->maxRange;
                simulatedObs.rightToLeft = o->rightToLeft;
                simulatedObs.sensorPose = o->sensorPose;
 
                // Performs the scan simulation:
                laserScanSimulator(
                        simulatedObs,  // The in/out observation
                        takenFrom,  // robot pose
                        0.45f,  // Cells threshold
                        nRays,  // Scan length
                        0, decimation);
 
                double stdLaser = likelihoodOptions.rayTracing_stdHit;
                double stdSqrt2 = sqrt(2.0f) * stdLaser;
 
                // Compute likelihoods:
                ret = 1;
                // bool         useDF = likelihoodOptions.rayTracing_useDistanceFilter;
                float r_sim, r_obs;
                double likelihood;
 
                for (int j = 0; j < nRays; j += decimation)
                {
                        // Simulated and measured ranges:
                        r_sim = simulatedObs.scan[j];
                        r_obs = o->scan[j];
 
                        // Is a valid range?
                        if (o->validRange[j])
                        {
                                likelihood =
                                        0.1 / o->maxRange +
                                        0.9 *
                                                exp(-square(
                                                        min((float)fabs(r_sim - r_obs), 2.0f) / stdSqrt2));
                                ret += log(likelihood);
                                // printf("Sim=%f\tReal=%f\tlik=%f\n",r_sim,r_obs,likelihood);
                        }
                }
        }
 
        return ret;
}
/**/
 
/*---------------------------------------------------------------
                        computeObservationLikelihood_likelihoodField_Thrun
---------------------------------------------------------------*/
double COccupancyGridMap2D::computeObservationLikelihood_likelihoodField_Thrun(
        const CObservation* obs, const CPose2D& takenFrom)
{
        MRPT_START
 
        double ret = 0;
 
        // This function depends on the observation type:
        // -----------------------------------------------------
        if (IS_CLASS(obs, CObservation2DRangeScan))
        {
                // Observation is a laser range scan:
                // -------------------------------------------
                const CObservation2DRangeScan* o =
                        static_cast<const CObservation2DRangeScan*>(obs);
 
                // Insert only HORIZONTAL scans, since the grid is supposed to
                //  be a horizontal representation of space.
                if (!o->isPlanarScan(insertionOptions.horizontalTolerance)) return -10;
 
                // Assure we have a 2D points-map representation of the points from the
                // scan:
                CPointsMap::TInsertionOptions opts;
                opts.minDistBetweenLaserPoints = resolution * 0.5f;
                opts.isPlanarMap = true;  // Already filtered above!
                opts.horizontalTolerance = insertionOptions.horizontalTolerance;
 
                // Compute the likelihood of the points in this grid map:
                ret = computeLikelihoodField_Thrun(
                        o->buildAuxPointsMap<mrpt::maps::CPointsMap>(&opts), &takenFrom);
 
        }  // end of observation is a scan range 2D
        else if (IS_CLASS(obs, CObservationRange))
        {
                // Sonar-like observations:
                // ---------------------------------------
                const CObservationRange* o = static_cast<const CObservationRange*>(obs);
 
                // Create a point map representation of the observation:
                CSimplePointsMap pts;
                pts.insertionOptions.minDistBetweenLaserPoints = resolution * 0.5f;
                pts.insertObservation(o);
 
                // Compute the likelihood of the points in this grid map:
                ret = computeLikelihoodField_Thrun(&pts, &takenFrom);
        }
 
        return ret;
 
        MRPT_END
}
 
/*---------------------------------------------------------------
                computeObservationLikelihood_likelihoodField_II
---------------------------------------------------------------*/
double COccupancyGridMap2D::computeObservationLikelihood_likelihoodField_II(
        const CObservation* obs, const CPose2D& takenFrom)
{
        MRPT_START
 
        double ret = 0;
 
        // This function depends on the observation type:
        // -----------------------------------------------------
        if (obs->GetRuntimeClass() == CLASS_ID(CObservation2DRangeScan))
        {
                // Observation is a laser range scan:
                // -------------------------------------------
                const CObservation2DRangeScan* o =
                        static_cast<const CObservation2DRangeScan*>(obs);
 
                // Insert only HORIZONTAL scans, since the grid is supposed to
                //  be a horizontal representation of space.
                if (!o->isPlanarScan(insertionOptions.horizontalTolerance))
                        return 0.5f;  // NO WAY TO ESTIMATE NON HORIZONTAL SCANS!!
 
                // Assure we have a 2D points-map representation of the points from the
                // scan:
 
                // Compute the likelihood of the points in this grid map:
                ret = computeLikelihoodField_II(
                        o->buildAuxPointsMap<mrpt::maps::CPointsMap>(), &takenFrom);
 
        }  // end of observation is a scan range 2D
 
        return ret;
 
        MRPT_END
}
 
/*---------------------------------------------------------------
                                        computeLikelihoodField_Thrun
 ---------------------------------------------------------------*/
double COccupancyGridMap2D::computeLikelihoodField_Thrun(
        const CPointsMap* pm, const CPose2D* relativePose)
{
        MRPT_START
 
        double ret;
        size_t N = pm->size();
        int K = (int)ceil(
                likelihoodOptions.LF_maxCorrsDistance /*m*/ /
                resolution);  // The size of the checking area for matchings:
 
        bool Product_T_OrSum_F = !likelihoodOptions.LF_alternateAverageMethod;
 
        if (!N)
        {
                return -100;  // No way to estimate this likelihood!!
        }
 
        // Compute the likelihoods for each point:
        ret = 0;
 
        float stdHit = likelihoodOptions.LF_stdHit;
        float zHit = likelihoodOptions.LF_zHit;
        float zRandom = likelihoodOptions.LF_zRandom;
        float zRandomMaxRange = likelihoodOptions.LF_maxRange;
        float zRandomTerm = zRandom / zRandomMaxRange;
        float Q = -0.5f / square(stdHit);
        int M = 0;
 
        unsigned int size_x_1 = size_x - 1;
        unsigned int size_y_1 = size_y - 1;
 
#define LIK_LF_CACHE_INVALID (66)
 
        // Aux. variables for the "for j" loop:
        double thisLik = LIK_LF_CACHE_INVALID;
        double maxCorrDist_sq = square(likelihoodOptions.LF_maxCorrsDistance);
        double minimumLik = zRandomTerm + zHit * exp(Q * maxCorrDist_sq);
        double ccos, ssin;
        float occupiedMinDist;
 
        if (likelihoodOptions.enableLikelihoodCache)
        {
                // Reset the precomputed likelihood values map
                if (precomputedLikelihoodToBeRecomputed)
                {
                        if (!map.empty())
                                precomputedLikelihood.assign(map.size(), LIK_LF_CACHE_INVALID);
                        else
                                precomputedLikelihood.clear();
 
                        precomputedLikelihoodToBeRecomputed = false;
                }
        }
 
        cellType thresholdCellValue = p2l(0.5f);
        int decimation = likelihoodOptions.LF_decimation;
 
        const double _resolution = this->resolution;
        const double constDist2DiscrUnits = 100 / (_resolution * _resolution);
        const double constDist2DiscrUnits_INV = 1.0 / constDist2DiscrUnits;
 
        if (N < 10) decimation = 1;
 
        TPoint2D pointLocal;
        TPoint2D pointGlobal;
 
        for (size_t j = 0; j < N; j += decimation)
        {
                occupiedMinDist = maxCorrDist_sq;  // The max.distance
 
                // Get the point and pass it to global coordinates:
                if (relativePose)
                {
                        pm->getPoint(j, pointLocal);
// pointGlobal = *relativePose + pointLocal;
#ifdef HAVE_SINCOS
                        ::sincos(relativePose->phi(), &ssin, &ccos);
#else
                        ccos = cos(relativePose->phi());
                        ssin = sin(relativePose->phi());
#endif
                        pointGlobal.x =
                                relativePose->x() + pointLocal.x * ccos - pointLocal.y * ssin;
                        pointGlobal.y =
                                relativePose->y() + pointLocal.x * ssin + pointLocal.y * ccos;
                }
                else
                {
                        pm->getPoint(j, pointGlobal);
                }
 
                // Point to cell indixes
                int cx = x2idx(pointGlobal.x);
                int cy = y2idx(pointGlobal.y);
 
                // Precomputed table:
                // Tip: Comparison cx<0 is implicit in (unsigned)(x)>size...
                if (static_cast<unsigned>(cx) >= size_x_1 ||
                        static_cast<unsigned>(cy) >= size_y_1)
                {
                        // We are outside of the map: Assign the likelihood for the max.
                        // correspondence distance:
                        thisLik = minimumLik;
                }
                else
                {
                        // We are into the map limits:
                        if (likelihoodOptions.enableLikelihoodCache)
                        {
                                thisLik = precomputedLikelihood[cx + cy * size_x];
                        }
 
                        if (!likelihoodOptions.enableLikelihoodCache ||
                                thisLik == LIK_LF_CACHE_INVALID)
                        {
                                // Compute now:
                                // -------------
                                // Find the closest occupied cell in a certain range, given by
                                // K:
                                int xx1 = max(0, cx - K);
                                int xx2 = min(size_x_1, (unsigned)(cx + K));
                                int yy1 = max(0, cy - K);
                                int yy2 = min(size_y_1, (unsigned)(cy + K));
 
                                // Optimized code: this part will be invoked a *lot* of times:
                                {
                                        cellType* mapPtr =
                                                &map[xx1 + yy1 * size_x];  // Initial pointer position
                                        unsigned incrAfterRow = size_x - ((xx2 - xx1) + 1);
 
                                        signed int Ax0 = 10 * (xx1 - cx);
                                        signed int Ay = 10 * (yy1 - cy);
 
                                        unsigned int occupiedMinDistInt = mrpt::utils::round(
                                                maxCorrDist_sq * constDist2DiscrUnits);
 
                                        for (int yy = yy1; yy <= yy2; yy++)
                                        {
                                                unsigned int Ay2 =
                                                        square((unsigned int)(Ay));  // Square is faster
                                                // with unsigned.
                                                signed short Ax = Ax0;
                                                cellType cell;
 
                                                for (int xx = xx1; xx <= xx2; xx++)
                                                {
                                                        if ((cell = *mapPtr++) < thresholdCellValue)
                                                        {
                                                                unsigned int d =
                                                                        square((unsigned int)(Ax)) + Ay2;
                                                                keep_min(occupiedMinDistInt, d);
                                                        }
                                                        Ax += 10;
                                                }
                                                // Go to (xx1,yy++)
                                                mapPtr += incrAfterRow;
                                                Ay += 10;
                                        }
 
                                        occupiedMinDist =
                                                occupiedMinDistInt * constDist2DiscrUnits_INV;
                                }
 
                                if (likelihoodOptions.LF_useSquareDist)
                                        occupiedMinDist *= occupiedMinDist;
 
                                thisLik = zRandomTerm + zHit * exp(Q * occupiedMinDist);
 
                                if (likelihoodOptions.enableLikelihoodCache)
                                        // And save it into the table and into "thisLik":
                                        precomputedLikelihood[cx + cy * size_x] = thisLik;
                        }
                }
 
                // Update the likelihood:
                if (Product_T_OrSum_F)
                {
                        ret += log(thisLik);
                }
                else
                {
                        ret += thisLik;
                        M++;
                }
        }  // end of for each point in the scan
 
        if (!Product_T_OrSum_F) ret = log(ret / M);
 
        return ret;
 
        MRPT_END
}
 
/*---------------------------------------------------------------
                                        computeLikelihoodField_II
 ---------------------------------------------------------------*/
double COccupancyGridMap2D::computeLikelihoodField_II(
        const CPointsMap* pm, const CPose2D* relativePose)
{
        MRPT_START
 
        double ret;
        size_t N = pm->size();
 
        if (!N) return 1e-100;  // No way to estimate this likelihood!!
 
        // Compute the likelihoods for each point:
        ret = 0;
        //      if (likelihoodOptions.LF_alternateAverageMethod)
        //                      ret = 0;
        //      else    ret = 1;
 
        TPoint2D pointLocal, pointGlobal;
 
        float zRandomTerm = 1.0f / likelihoodOptions.LF_maxRange;
        float Q = -0.5f / square(likelihoodOptions.LF_stdHit);
 
        // Aux. cell indixes variables:
        int cx, cy;
        size_t j;
        int cx0, cy0;
        int cx_min, cx_max;
        int cy_min, cy_max;
        int maxRangeInCells =
                (int)ceil(likelihoodOptions.LF_maxCorrsDistance / resolution);
        int nCells = 0;
 
        // -----------------------------------------------------
        // Compute around a window of neigbors around each point
        // -----------------------------------------------------
        for (j = 0; j < N; j += likelihoodOptions.LF_decimation)
        {
                // Get the point and pass it to global coordinates:
                // ---------------------------------------------
                if (relativePose)
                {
                        pm->getPoint(j, pointLocal);
                        pointGlobal = *relativePose + pointLocal;
                }
                else
                {
                        pm->getPoint(j, pointGlobal);
                }
 
                // Point to cell indixes:
                // ---------------------------------------------
                cx0 = x2idx(pointGlobal.x);
                cy0 = y2idx(pointGlobal.y);
 
                // Compute the range of cells to compute:
                // ---------------------------------------------
                cx_min = max(cx0 - maxRangeInCells, 0);
                cx_max = min(cx0 + maxRangeInCells, static_cast<int>(size_x));
                cy_min = max(cy0 - maxRangeInCells, 0);
                cy_max = min(cy0 + maxRangeInCells, static_cast<int>(size_y));
 
                //              debugImg.rectangle(cx_min,cy_min,cx_max,cy_max,0xFF0000 );
 
                // Compute over the window of cells:
                // ---------------------------------------------
                double lik = 0;
                for (cx = cx_min; cx <= cx_max; cx++)
                {
                        for (cy = cy_min; cy <= cy_max; cy++)
                        {
                                float P_free = getCell(cx, cy);
                                float termDist =
                                        exp(Q * (square(idx2x(cx) - pointGlobal.x) +
                                                         square(idx2y(cy) - pointGlobal.y)));
 
                                lik += P_free * zRandomTerm + (1 - P_free) * termDist;
                        }  // end for cy
                }  // end for cx
 
                // Update the likelihood:
                if (likelihoodOptions.LF_alternateAverageMethod)
                        ret += lik;
                else
                        ret += log(lik / ((cy_max - cy_min + 1) * (cx_max - cx_min + 1)));
                nCells++;
 
        }  // end of for each point in the scan
 
        if (likelihoodOptions.LF_alternateAverageMethod && nCells > 0)
                ret = log(ret / nCells);
        else
                ret = ret / nCells;
 
        return ret;
 
        MRPT_END
}
 
/*---------------------------------------------------------------
        Initilization of values, don't needed to be called directly.
  ---------------------------------------------------------------*/
COccupancyGridMap2D::TLikelihoodOptions::TLikelihoodOptions()
        : likelihoodMethod(lmLikelihoodField_Thrun),
 
          LF_stdHit(0.35f),
          LF_zHit(0.95f),
          LF_zRandom(0.05f),
          LF_maxRange(81.0f),
          LF_decimation(5),
          LF_maxCorrsDistance(0.3f),
          LF_useSquareDist(false),
          LF_alternateAverageMethod(false),
 
          MI_exponent(2.5f),
          MI_skip_rays(10),
          MI_ratio_max_distance(1.5f),
 
          rayTracing_useDistanceFilter(true),
          rayTracing_decimation(10),
          rayTracing_stdHit(1.0f),
 
          consensus_takeEachRange(1),
          consensus_pow(5),
          OWA_weights(100, 1 / 100.0f),
 
          enableLikelihoodCache(true)
{
}
 
/*---------------------------------------------------------------
                                        loadFromConfigFile
  ---------------------------------------------------------------*/
void COccupancyGridMap2D::TLikelihoodOptions::loadFromConfigFile(
        const mrpt::utils::CConfigFileBase& iniFile, const std::string& section)
{
        likelihoodMethod =
                iniFile.read_enum(section, "likelihoodMethod", likelihoodMethod);
 
        enableLikelihoodCache = iniFile.read_bool(
                section, "enableLikelihoodCache", enableLikelihoodCache);
 
        LF_stdHit = iniFile.read_float(section, "LF_stdHit", LF_stdHit);
        LF_zHit = iniFile.read_float(section, "LF_zHit", LF_zHit);
        LF_zRandom = iniFile.read_float(section, "LF_zRandom", LF_zRandom);
        LF_maxRange = iniFile.read_float(section, "LF_maxRange", LF_maxRange);
        LF_decimation = iniFile.read_int(section, "LF_decimation", LF_decimation);
        LF_maxCorrsDistance =
                iniFile.read_float(section, "LF_maxCorrsDistance", LF_maxCorrsDistance);
        LF_useSquareDist =
                iniFile.read_bool(section, "LF_useSquareDist", LF_useSquareDist);
        LF_alternateAverageMethod = iniFile.read_bool(
                section, "LF_alternateAverageMethod", LF_alternateAverageMethod);
 
        MI_exponent = iniFile.read_float(section, "MI_exponent", MI_exponent);
        MI_skip_rays = iniFile.read_int(section, "MI_skip_rays", MI_skip_rays);
        MI_ratio_max_distance = iniFile.read_float(
                section, "MI_ratio_max_distance", MI_ratio_max_distance);
 
        rayTracing_useDistanceFilter = iniFile.read_bool(
                section, "rayTracing_useDistanceFilter", rayTracing_useDistanceFilter);
        rayTracing_stdHit =
                iniFile.read_float(section, "rayTracing_stdHit", rayTracing_stdHit);
 
        consensus_takeEachRange = iniFile.read_int(
                section, "consensus_takeEachRange", consensus_takeEachRange);
        consensus_pow = iniFile.read_float(section, "consensus_pow", consensus_pow);
 
        iniFile.read_vector(section, "OWA_weights", OWA_weights, OWA_weights);
}
 
/*---------------------------------------------------------------
                                        dumpToTextStream
  ---------------------------------------------------------------*/
void COccupancyGridMap2D::TLikelihoodOptions::dumpToTextStream(
        mrpt::utils::CStream& out) const
{
        out.printf(
                "\n----------- [COccupancyGridMap2D::TLikelihoodOptions] ------------ "
                "\n\n");
 
        out.printf("likelihoodMethod                        = ");
        switch (likelihoodMethod)
        {
                case lmMeanInformation:
                        out.printf("lmMeanInformation");
                        break;
                case lmRayTracing:
                        out.printf("lmRayTracing");
                        break;
                case lmConsensus:
                        out.printf("lmConsensus");
                        break;
                case lmCellsDifference:
                        out.printf("lmCellsDifference");
                        break;
                case lmLikelihoodField_Thrun:
                        out.printf("lmLikelihoodField_Thrun");
                        break;
                case lmLikelihoodField_II:
                        out.printf("lmLikelihoodField_II");
                        break;
                case lmConsensusOWA:
                        out.printf("lmConsensusOWA");
                        break;
                default:
                        out.printf("UNKNOWN!!!");
                        break;
        }
        out.printf("\n");
 
        out.printf(
                "enableLikelihoodCache                   = %c\n",
                enableLikelihoodCache ? 'Y' : 'N');
 
        out.printf("LF_stdHit                               = %f\n", LF_stdHit);
        out.printf("LF_zHit                                 = %f\n", LF_zHit);
        out.printf("LF_zRandom                              = %f\n", LF_zRandom);
        out.printf("LF_maxRange                             = %f\n", LF_maxRange);
        out.printf("LF_decimation                           = %u\n", LF_decimation);
        out.printf(
                "LF_maxCorrsDistance                     = %f\n", LF_maxCorrsDistance);
        out.printf(
                "LF_useSquareDist                        = %c\n",
                LF_useSquareDist ? 'Y' : 'N');
        out.printf(
                "LF_alternateAverageMethod               = %c\n",
                LF_alternateAverageMethod ? 'Y' : 'N');
        out.printf("MI_exponent                             = %f\n", MI_exponent);
        out.printf("MI_skip_rays                            = %u\n", MI_skip_rays);
        out.printf(
                "MI_ratio_max_distance                   = %f\n",
                MI_ratio_max_distance);
        out.printf(
                "rayTracing_useDistanceFilter            = %c\n",
                rayTracing_useDistanceFilter ? 'Y' : 'N');
        out.printf(
                "rayTracing_decimation                   = %u\n",
                rayTracing_decimation);
        out.printf(
                "rayTracing_stdHit                       = %f\n", rayTracing_stdHit);
        out.printf(
                "consensus_takeEachRange                 = %u\n",
                consensus_takeEachRange);
        out.printf(
                "consensus_pow                           = %.02f\n", consensus_pow);
        out.printf("OWA_weights   = [");
        for (size_t i = 0; i < OWA_weights.size(); i++)
        {
                if (i < 3 || i > (OWA_weights.size() - 3))
                        out.printf("%.03f ", OWA_weights[i]);
                else if (i == 3 && OWA_weights.size() > 6)
                        out.printf(" ... ");
        }
        out.printf("] (size=%u)\n", (unsigned)OWA_weights.size());
        out.printf("\n");
}
 
/** Returns true if this map is able to compute a sensible likelihood function
 * for this observation (i.e. an occupancy grid map cannot with an image).
 * \param obs The observation.
 * \sa computeObservationLikelihood
 */
bool COccupancyGridMap2D::internal_canComputeObservationLikelihood(
        const mrpt::obs::CObservation* obs) const
{
        // Ignore laser scans if they are not planar or they are not
        //  at the altitude of this grid map:
        if (obs->GetRuntimeClass() == CLASS_ID(CObservation2DRangeScan))
        {
                const CObservation2DRangeScan* scan =
                        static_cast<const CObservation2DRangeScan*>(obs);
 
                if (!scan->isPlanarScan(insertionOptions.horizontalTolerance))
                        return false;
                if (insertionOptions.useMapAltitude &&
                        fabs(insertionOptions.mapAltitude - scan->sensorPose.z()) > 0.01)
                        return false;
 
                // OK, go on...
                return true;
        }
        else  // Is not a laser scanner...
        {
                return false;
        }
}