Example: slam_icp_simple_example

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/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;
  }
}