Example: math_ransac_plane3d_example2
This example shows how to use MRPT’s RANSAC C++ template to detect planes from a 3D point cloud given as a mrpt::maps::CPointsMap.
See also the RANSAC tutorial page.
![math_ransac_plane3d_example2 screenshot](_images/math_ransac_plane3d_example2_screenshot.gif)
![math_ransac_plane3d_example2 screenshot](_images/math_ransac_plane3d_example2_screenshot.gif)
![math_ransac_plane3d_example2 screenshot](_images/math_ransac_plane3d_example2_screenshot.gif)
![math_ransac_plane3d_example2 screenshot](_images/math_ransac_plane3d_example2_screenshot.gif)
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/ransac.h> #include <mrpt/opengl/CGridPlaneXY.h> #include <mrpt/opengl/CPointCloud.h> #include <mrpt/opengl/CTexturedPlane.h> #include <mrpt/opengl/stock_objects.h> #include <mrpt/poses/CPose3D.h> #include <mrpt/random.h> #include <mrpt/system/CTicTac.h> #include <iostream> using namespace mrpt; using namespace mrpt::gui; using namespace mrpt::math; using namespace mrpt::random; using namespace mrpt::poses; using namespace mrpt::system; using namespace std; // Define as needed for your application: using MyRansac = mrpt::math::RANSAC_Template< float, // Numeric data type: float since pointclouds use float mrpt::maps::CPointsMap, // Dataset type (can be an abstract base type) mrpt::math::TPlane // Model type to be estimated >; namespace mrpt::math { // Overload for your custom dataset type: size_t ransacDatasetSize(const mrpt::maps::CPointsMap& dataset) { return dataset.size(); } } // namespace mrpt::math void ransac3Dplane_fit( const mrpt::maps::CPointsMap& allData, const std::vector<size_t>& useIndices, vector<mrpt::math::TPlane>& fitModels) { ASSERT_(useIndices.size() == 3); TPoint3D pt[3]; for (int i = 0; i < 3; i++) allData.getPoint(useIndices[i], pt[i]); try { fitModels.resize(1); fitModels[0] = TPlane(pt[0], pt[1], pt[2]); } catch (exception&) { // If the three points are degenerated, an exception may be thrown in // the plane ctor fitModels.clear(); return; } } void ransac3Dplane_distance( const mrpt::maps::CPointsMap& allData, const vector<mrpt::math::TPlane>& testModels, const double distanceThreshold, unsigned int& out_bestModelIndex, std::vector<size_t>& out_inlierIndices) { ASSERT_(testModels.size() == 1); out_bestModelIndex = 0; const mrpt::math::TPlane& plane = testModels[0]; const size_t N = allData.size(); out_inlierIndices.clear(); out_inlierIndices.reserve(100); for (size_t i = 0; i < N; i++) { mrpt::math::TPoint3D pt; allData.getPoint(i, pt); const double d = plane.distance(pt); if (d < distanceThreshold) out_inlierIndices.push_back(i); } } bool ransac3Dplane_degenerate( const mrpt::maps::CPointsMap& allData, const std::vector<size_t>& useIndices) { return false; } // ------------------------------------------------------ // TestRANSAC // ------------------------------------------------------ void TestRANSAC() { auto& rng = getRandomGenerator(); rng.randomize(); // Generate random points: // ------------------------------------ const size_t N_plane = 300; const size_t N_noise = 100; const double PLANE_EQ[4] = {1, -1, 1, -2}; mrpt::maps::CSimplePointsMap data; data.reserve(N_plane + N_noise); for (size_t i = 0; i < N_plane; i++) { const double xx = rng.drawUniform(-3, 3); const double yy = rng.drawUniform(-3, 3); const double zz = -(PLANE_EQ[3] + PLANE_EQ[0] * xx + PLANE_EQ[1] * yy) / PLANE_EQ[2]; data.insertPointFast(xx, yy, zz); } for (size_t i = 0; i < N_noise; i++) { data.insertPointFast( rng.drawUniform(-4, 4), rng.drawUniform(-4, 4), rng.drawUniform(-4, 4)); } // Run RANSAC // ------------------------------------ mrpt::math::TPlane best_model; std::vector<size_t> best_inliers; const double DIST_THRESHOLD = 0.05; CTicTac tictac; MyRansac myransac; myransac.setVerbosityLevel(mrpt::system::LVL_DEBUG); myransac.execute( data, &ransac3Dplane_fit, &ransac3Dplane_distance, &ransac3Dplane_degenerate, DIST_THRESHOLD, 3, // Minimum set of points best_inliers, best_model); cout << "Computation time: " << tictac.Tac() * 1000.0 << " ms\n"; cout << "RANSAC finished: Best model: " << best_model.coefs[0] << " " << best_model.coefs[1] << " " << best_model.coefs[2] << " " << best_model.coefs[3] << endl; // Show GUI // -------------------------- mrpt::gui::CDisplayWindow3D win("Set of points", 500, 500); opengl::Scene::Ptr scene = opengl::Scene::Create(); scene->insert(opengl::CGridPlaneXY::Create(-20, 20, -20, 20, 0, 1)); scene->insert(opengl::stock_objects::CornerXYZ()); opengl::CPointCloud::Ptr points = opengl::CPointCloud::Create(); points->setColor(0, 0, 1); points->setPointSize(3); points->enableColorFromZ(); points->loadFromPointsMap(&data); scene->insert(points); opengl::CTexturedPlane::Ptr glPlane = opengl::CTexturedPlane::Create(-4, 4, -4, 4); glPlane->setColor_u8(mrpt::img::TColor(0xff, 0x00, 0x00, 0x80)); // RGBA TPose3D glPlanePose; best_model.getAsPose3D(glPlanePose); glPlane->setPose(glPlanePose); scene->insert(glPlane); win.get3DSceneAndLock() = scene; win.unlockAccess3DScene(); win.forceRepaint(); win.waitForKey(); } // ------------------------------------------------------ // 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; } }