Example: maps_ransac_data_association

maps_ransac_data_association screenshot maps_ransac_data_association screenshot maps_ransac_data_association screenshot maps_ransac_data_association screenshot

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2024, 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 <mrpt/gui/CDisplayWindow3D.h>
#include <mrpt/maps/CSimplePointsMap.h>
#include <mrpt/math/geometry.h>
#include <mrpt/opengl/CPointCloud.h>
#include <mrpt/opengl/CSetOfLines.h>
#include <mrpt/opengl/stock_objects.h>
#include <mrpt/poses/CPose2D.h>
#include <mrpt/poses/CPosePDFGaussian.h>
#include <mrpt/poses/CPosePDFSOG.h>
#include <mrpt/random.h>
#include <mrpt/system/CTicTac.h>
#include <mrpt/system/CTimeLogger.h>
#include <mrpt/tfest/se2.h>

#include <iostream>

// Method explained in paper:
//  J.L. Blanco, J. Gonzalez-Jimenez, J.A. Fernandez-Madrigal,
//   "A Robust, Multi-Hypothesis Approach to Matching Occupancy Grid Maps",
//    Robotica, 2013.
// http://dx.doi.org/10.1017/S0263574712000732

// ============= PARAMETERS ===================
const size_t NUM_OBSERVATIONS_TO_SIMUL = 10;
const size_t RANSAC_MINIMUM_INLIERS = 9;  // Min. # of inliers to accept

#define LOAD_MAP_FROM_FILE 0  // 1: load from "sMAP_FILE", 0: random map.
#define SHOW_POINT_LABELS 0

const float normalizationStd = 0.15f;  // 1 sigma noise (meters)
const float ransac_mahalanobisDistanceThreshold = 5.0f;
const size_t MINIMUM_RANSAC_ITERS = 100000;

#if !LOAD_MAP_FROM_FILE
const size_t NUM_MAP_FEATS = 100;
const double MAP_SIZE_X = 50;
const double MAP_SIZE_Y = 25;
#else
// Expected format of the 2D map is, for each line (one per landmark):
//  ID X Y
const std::string sMAP_FILE = string("./DLRMap.txt");
#endif
// ==============================================

using namespace mrpt;
using namespace mrpt::math;
using namespace mrpt::random;
using namespace mrpt::maps;
using namespace mrpt::tfest;
using namespace mrpt::img;
using namespace std;

struct TObs
{
    size_t ID;  // Ground truth ID
    double x, y;
};

// ------------------------------------------------------
//              TestRANSAC
// ------------------------------------------------------
void TestRANSAC()
{
    mrpt::gui::CDisplayWindow3D win(
        "MRPT example: ransac-data-association", 800, 600);

    mrpt::system::CTimeLogger timelog;  // For dumping stats at the end
    mrpt::system::CTicTac timer;

    getRandomGenerator().randomize();  // randomize with time

    // --------------------------------
    // Load feature map:
    // --------------------------------
    CSimplePointsMap the_map;
#if LOAD_MAP_FROM_FILE
    {
        CMatrixDouble M;
        M.loadFromTextFile(sMAP_FILE);  // Launch except. on error
        ASSERT_(M.cols() == 3 && M.rows() > 2)

        const size_t nPts = M.rows();
        the_map.resize(nPts);
        for (size_t i = 0; i < nPts; i++)
            the_map.setPoint(i, M(i, 1), M(i, 2));
    }
#else
    // Generate random MAP:
    the_map.resize(NUM_MAP_FEATS);
    for (size_t i = 0; i < NUM_MAP_FEATS; i++)
    {
        the_map.setPoint(
            i, getRandomGenerator().drawUniform(0, MAP_SIZE_X),
            getRandomGenerator().drawUniform(0, MAP_SIZE_Y));
    }
#endif

    const size_t nMapPts = the_map.size();
    cout << "Loaded/generated map with " << nMapPts << " landmarks.\n";

    const size_t nObs = NUM_OBSERVATIONS_TO_SIMUL;

    mrpt::opengl::CPointCloud::Ptr gl_obs_map =
        mrpt::opengl::CPointCloud::Create();
    mrpt::opengl::CPointCloud::Ptr gl_result =
        mrpt::opengl::CPointCloud::Create();
    mrpt::opengl::CSetOfObjects::Ptr gl_obs =
        mrpt::opengl::CSetOfObjects::Create();
    mrpt::opengl::CSetOfObjects::Ptr gl_obs_txts =
        mrpt::opengl::CSetOfObjects::Create();
    mrpt::opengl::CSetOfLines::Ptr gl_lines =
        mrpt::opengl::CSetOfLines::Create();
    {
        mrpt::opengl::Scene::Ptr& scene = win.get3DSceneAndLock();

        scene->getViewport("main")->setCustomBackgroundColor(
            TColorf(0.8f, 0.8f, 0.8f));
        win.setCameraPointingToPoint(MAP_SIZE_X * 0.5, MAP_SIZE_Y * 0.5, 0);
        win.setCameraZoom(2 * MAP_SIZE_X);

        //
        scene->insert(mrpt::opengl::stock_objects::CornerXYZ());

        //
        mrpt::opengl::CPointCloud::Ptr gl_map =
            mrpt::opengl::CPointCloud::Create();
        gl_map->loadFromPointsMap(&the_map);
        gl_map->setColor(0, 0, 1);
        gl_map->setPointSize(3);

        scene->insert(gl_map);

#if SHOW_POINT_LABELS
        for (size_t i = 0; i < the_map.size(); i++)
        {
            mrpt::opengl::CText::Ptr gl_txt = mrpt::opengl::CText::Create(
                mrpt::format("%u", static_cast<unsigned int>(i)));
            double x, y;
            the_map.getPoint(i, x, y);
            gl_txt->setLocation(x + 0.05, y + 0.05, 0.01);

            scene->insert(gl_txt);
        }
#endif

        //
        scene->insert(gl_lines);

        //
        gl_obs_map->setColor(1, 0, 0);
        gl_obs_map->setPointSize(5);

        gl_result->setColor(0, 1, 0);
        gl_result->setPointSize(4);

        //
        gl_obs->insert(mrpt::opengl::stock_objects::CornerXYZ(0.6f));
        gl_obs->insert(gl_obs_map);
        gl_obs->insert(gl_obs_txts);
        scene->insert(gl_obs);
        scene->insert(gl_result);

        win.unlockAccess3DScene();
        win.repaint();
    }

    // Repeat for each set of observations in the input file
    while (win.isOpen())
    {
        // Read the observations themselves:
        vector<TObs> observations;
        observations.resize(nObs);

        const mrpt::poses::CPose2D GT_pose(
            mrpt::random::getRandomGenerator().drawUniform(
                -10, 10 + MAP_SIZE_X),
            mrpt::random::getRandomGenerator().drawUniform(
                -10, 10 + MAP_SIZE_Y),
            mrpt::random::getRandomGenerator().drawUniform(-M_PI, M_PI));

        const mrpt::poses::CPose2D GT_pose_inv = -GT_pose;

        std::vector<nanoflann::ResultItem<size_t, float>> idxs;
        the_map.kdTreeRadiusSearch2D(GT_pose.x(), GT_pose.y(), 1000, idxs);
        ASSERT_(idxs.size() >= nObs);

        for (size_t i = 0; i < nObs; i++)
        {
            double gx, gy;
            the_map.getPoint(idxs[i].first, gx, gy);

            double lx, ly;
            GT_pose_inv.composePoint(gx, gy, lx, ly);

            observations[i].ID = idxs[i].first;
            observations[i].x = lx +
                mrpt::random::getRandomGenerator().drawGaussian1D(
                    0, normalizationStd);
            observations[i].y = ly +
                mrpt::random::getRandomGenerator().drawGaussian1D(
                    0, normalizationStd);
        }

        // ----------------------------------------------------
        // Generate list of individual-compatible pairings
        // ----------------------------------------------------
        TMatchingPairList all_correspondences;

        all_correspondences.reserve(nMapPts * nObs);

        // ALL possibilities:
        for (size_t j = 0; j < nObs; j++)
        {
            TMatchingPair match;

            match.localIdx = j;
            match.local.x = observations[j].x;
            match.local.y = observations[j].y;

            for (size_t i = 0; i < nMapPts; i++)
            {
                match.globalIdx = i;
                the_map.getPoint(i, match.global.x, match.global.y);

                all_correspondences.push_back(match);
            }
        }
        cout << "Generated " << all_correspondences.size()
             << " potential pairings.\n";

        // ----------------------------------------------------
        //  Run RANSAC-based D-A
        // ----------------------------------------------------
        timelog.enter("robustRigidTransformation");
        timer.Tic();

        mrpt::tfest::TSE2RobustParams params;
        mrpt::tfest::TSE2RobustResult results;

        params.ransac_minSetSize =
            RANSAC_MINIMUM_INLIERS;  // ransac_minSetSize (to add the solution
        // to the SOG)
        params.ransac_maxSetSize =
            all_correspondences
                .size();  // ransac_maxSetSize: Test with all data points
        params.ransac_mahalanobisDistanceThreshold =
            ransac_mahalanobisDistanceThreshold;
        params.ransac_nSimulations = 0;  // 0=auto
        params.ransac_fuseByCorrsMatch = true;
        params.ransac_fuseMaxDiffXY = 0.01f;
        params.ransac_fuseMaxDiffPhi = 0.1_deg;
        params.ransac_algorithmForLandmarks = true;
        params.probability_find_good_model = 0.999999;
        params.ransac_min_nSimulations =
            MINIMUM_RANSAC_ITERS;  // (a lower limit to the auto-detected value
        // of ransac_nSimulations)
        params.verbose = true;

        // Run ransac data-association:
        mrpt::tfest::se2_l2_robust(
            all_correspondences, normalizationStd, params, results);

        timelog.leave("robustRigidTransformation");

        mrpt::poses::CPosePDFSOG& best_poses = results.transformation;
        TMatchingPairList& out_best_pairings = results.largestSubSet;

        const double tim = timer.Tac();
        cout << "RANSAC time: " << mrpt::system::formatTimeInterval(tim)
             << endl;

        cout << "# of SOG modes: " << best_poses.size() << endl;
        cout << "Best match has " << out_best_pairings.size() << " features:\n";
        for (size_t i = 0; i < out_best_pairings.size(); i++)
            cout << out_best_pairings[i].globalIdx << " <-> "
                 << out_best_pairings[i].localIdx << endl;
        cout << endl;

        // Generate "association vector":
        vector<int> obs2map_pairings(nObs, -1);
        for (size_t i = 0; i < out_best_pairings.size(); i++)
            obs2map_pairings[out_best_pairings[i].localIdx] =
                out_best_pairings[i].globalIdx == ((unsigned int)-1)
                ? -1
                : out_best_pairings[i].globalIdx;

        cout << "1\n";
        for (size_t i = 0; i < nObs; i++)
            cout << obs2map_pairings[i] << " ";
        cout << endl;

        gl_result->clear();

        // Reconstruct the SE(2) transformation for these pairings:
        mrpt::poses::CPosePDFGaussian solution_pose;
        mrpt::tfest::se2_l2(out_best_pairings, solution_pose);

        // Normalized covariance: scale!
        solution_pose.cov *= square(normalizationStd);

        cout << "Solution pose: " << solution_pose.mean << endl;
        cout << "Ground truth pose: " << GT_pose << endl;

        {
            // mrpt::opengl::Scene::Ptr &scene =
            win.get3DSceneAndLock();

            win.addTextMessage(
                5, 5,
                "Blue: map landmarks | Red: Observations | White lines: Found "
                "correspondences",
                0);

            //
            gl_obs_map->clear();
            for (size_t k = 0; k < nObs; k++)
                gl_obs_map->insertPoint(
                    observations[k].x, observations[k].y, 0.0);

            gl_obs->setPose(solution_pose.mean);

#if SHOW_POINT_LABELS
            gl_obs_txts->clear();
            for (size_t i = 0; i < nObs; i++)
            {
                mrpt::opengl::CText::Ptr gl_txt = mrpt::opengl::CText::Create(
                    mrpt::format("%u", static_cast<unsigned int>(i)));
                const double x = observations[i].x;
                const double y = observations[i].y;
                gl_txt->setLocation(x + 0.05, y + 0.05, 0.01);
                gl_obs_txts->insert(gl_txt);
            }
#endif

            //
            gl_lines->clear();
            double sqerr = 0;
            size_t nPairs = 0;
            for (size_t k = 0; k < nObs; k++)
            {
                int map_idx = obs2map_pairings[k];
                if (map_idx < 0) continue;
                nPairs++;

                double map_x, map_y;
                the_map.getPoint(map_idx, map_x, map_y);

                double obs_x, obs_y;
                solution_pose.mean.composePoint(
                    observations[k].x, observations[k].y, obs_x, obs_y);

                const double z = 0;

                gl_lines->appendLine(map_x, map_y, 0, obs_x, obs_y, z);

                sqerr += mrpt::math::distanceSqrBetweenPoints<double>(
                    map_x, map_y, obs_x, obs_y);
            }

            win.addTextMessage(
                5, 20, "Ground truth pose    : " + GT_pose.asString(), 1);
            win.addTextMessage(
                5, 35,
                "RANSAC estimated pose: " + solution_pose.mean.asString() +
                    mrpt::format(" | RMSE=%f", (nPairs ? sqerr / nPairs : 0.0)),
                2);

            win.unlockAccess3DScene();
            win.repaint();

            cout << "nPairings: " << nPairs
                 << " RMSE = " << (nPairs ? sqerr / nPairs : 0.0) << endl;

            win.waitForKey();
        }

    }  // end of for each set of observations
}

// ------------------------------------------------------
//                      MAIN
// ------------------------------------------------------
int main()
{
    try
    {
        TestRANSAC();
        return 0;
    }
    catch (const std::exception& e)
    {
        std::cerr << "MRPT error: " << mrpt::exception_to_str(e) << std::endl;
        return -1;
    }
}