Example: slam_icp_simple_example

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2023, 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/CDisplayWindowPlots.h>
#include <mrpt/maps/CSimplePointsMap.h>
#include <mrpt/math/utils.h>
#include <mrpt/obs/CObservation2DRangeScan.h>
#include <mrpt/obs/stock_observations.h>
#include <mrpt/poses/CPose2D.h>
#include <mrpt/poses/CPosePDF.h>
#include <mrpt/poses/CPosePDFGaussian.h>
#include <mrpt/slam/CICP.h>

#include <fstream>
#include <iostream>

using namespace mrpt;
using namespace mrpt::slam;
using namespace mrpt::maps;
using namespace mrpt::obs;
using namespace mrpt::math;
using namespace mrpt::poses;
using namespace std;

bool skip_window = false;
int ICP_method = (int)icpClassic;

// ------------------------------------------------------
//              TestICP
// ------------------------------------------------------
void TestICP()
{
    CSimplePointsMap m1, m2;
    CICP::TReturnInfo info;
    CICP ICP;

    // Load scans:
    CObservation2DRangeScan scan1;
    stock_observations::example2DRangeScan(scan1, 0);

    CObservation2DRangeScan scan2;
    stock_observations::example2DRangeScan(scan2, 1);

    // Build the points maps from the scans:
    m1.insertObservation(scan1);
    m2.insertObservation(scan2);

    // -----------------------------------------------------

    //  select which algorithm version to use
    //  ICP.options.ICP_algorithm = icpLevenbergMarquardt;
    //  ICP.options.ICP_algorithm = icpClassic;
    ICP.options.ICP_algorithm = (TICPAlgorithm)ICP_method;

    // configuration options for the icp algorithm
    ICP.options.maxIterations = 100;
    ICP.options.thresholdAng = DEG2RAD(10.0f);
    ICP.options.thresholdDist = 0.75f;
    ICP.options.ALFA = 0.5f;
    ICP.options.smallestThresholdDist = 0.05f;
    ICP.options.doRANSAC = false;

    ICP.options.dumpToConsole();
    // -----------------------------------------------------

    CPose2D initialPose(0.8f, 0.0f, (float)DEG2RAD(0.0f));

    CPosePDF::Ptr pdf = ICP.Align(&m1, &m2, initialPose, info);

    printf(
        "ICP run in %.02fms, %d iterations (%.02fms/iter), %.01f%% goodness\n "
        "-> ",
        info.executionTime * 1000, info.nIterations,
        info.executionTime * 1000.0f / info.nIterations, info.goodness * 100);

    cout << "Mean of estimation: " << pdf->getMeanVal() << endl << endl;

    CPosePDFGaussian gPdf;
    gPdf.copyFrom(*pdf);

    cout << "Covariance of estimation: " << endl << gPdf.cov << endl;

    cout << " std(x): " << sqrt(gPdf.cov(0, 0)) << endl;
    cout << " std(y): " << sqrt(gPdf.cov(1, 1)) << endl;
    cout << " std(phi): " << RAD2DEG(sqrt(gPdf.cov(2, 2))) << " (deg)" << endl;

    // cout << "Covariance of estimation (MATLAB format): " << endl <<
    // gPdf.cov.inMatlabFormat()  << endl;

    cout << "-> Saving reference map as scan1.txt" << endl;
    m1.save2D_to_text_file("scan1.txt");

    cout << "-> Saving map to align as scan2.txt" << endl;
    m2.save2D_to_text_file("scan2.txt");

    cout << "-> Saving transformed map to align as scan2_trans.txt" << endl;
    CSimplePointsMap m2_trans = m2;
    m2_trans.changeCoordinatesReference(gPdf.mean);
    m2_trans.save2D_to_text_file("scan2_trans.txt");

    cout << "-> Saving MATLAB script for drawing 2D ellipsoid as view_ellip.m"
         << endl;
    CMatrixFloat COV22 = CMatrixFloat(CMatrixDouble(gPdf.cov));
    COV22.setSize(2, 2);
    CVectorFloat MEAN2D(2);
    MEAN2D[0] = gPdf.mean.x();
    MEAN2D[1] = gPdf.mean.y();
    {
        ofstream f("view_ellip.m");
        f << math::MATLAB_plotCovariance2D(COV22, MEAN2D, 3.0f);
    }

// If we have 2D windows, use'em:
#if MRPT_HAS_WXWIDGETS
    if (!skip_window)
    {
        gui::CDisplayWindowPlots win("ICP results");

        // Reference map:
        vector<float> map1_xs, map1_ys, map1_zs;
        m1.getAllPoints(map1_xs, map1_ys, map1_zs);
        win.plot(map1_xs, map1_ys, "b.3", "map1");

        // Translated map:
        vector<float> map2_xs, map2_ys, map2_zs;
        m2_trans.getAllPoints(map2_xs, map2_ys, map2_zs);
        win.plot(map2_xs, map2_ys, "r.3", "map2");

        // Uncertainty
        win.plotEllipse(MEAN2D[0], MEAN2D[1], COV22, 3.0, "b2", "cov");

        win.axis(-1, 10, -6, 6);
        win.axis_equal();

        cout << "Close the window to exit" << endl;
        win.waitForKey();
    }
#endif
}

int main(int argc, char** argv)
{
    try
    {
        skip_window = (argc > 2);
        if (argc > 1) { ICP_method = atoi(argv[1]); }

        TestICP();

        return 0;
    }
    catch (exception& e)
    {
        cout << "MRPT exception caught: " << e.what() << endl;
        return -1;
    }
    catch (...)
    {
        printf("Another exception!!");
        return -1;
    }
}