Example: vision_stereo_rectify

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/config/CConfigFile.h>
#include <mrpt/gui/CDisplayWindow3D.h>
#include <mrpt/hwdrivers/CCameraSensor.h>
#include <mrpt/opengl/Scene.h>
#include <mrpt/system/CTimeLogger.h>
#include <mrpt/system/filesystem.h>  // for ASSERT_FILE_EXISTS_
#include <mrpt/vision/CStereoRectifyMap.h>

#include <chrono>
#include <iostream>
#include <thread>

using namespace mrpt;
using namespace mrpt::opengl;
using namespace mrpt::gui;
using namespace mrpt::vision;
using namespace mrpt::system;
using namespace mrpt::img;
using namespace mrpt::obs;
using namespace mrpt::system;
using namespace mrpt::config;
using namespace mrpt::img;
using namespace std;

// ------------------------------------------------------
//              TestStereoRectify
// ------------------------------------------------------
void TestStereoRectify(int argc, char** argv)
{
    CTimeLogger timlog;
    mrpt::vision::CStereoRectifyMap rectifyMap;

    // Parse optional arguments:
    if (argc != 1 && argc != 2)
    {
        cout
            << "Usage:\n"
            << argv[0]
            << " ==> Run with default camera parameters (from rawlog file)\n"
            << argv[0]
            << "[params.cfg] ==> Load stereo camera parameters from cfg file\n";
    }
    if (argc == 2)
    {
        const string sCfgFile = argv[1];
        ASSERT_FILE_EXISTS_(sCfgFile);

        // Load params from file:
        mrpt::img::TStereoCamera params;
        params.loadFromConfigFile(
            "CAMERA_PARAMS", mrpt::config::CConfigFile(sCfgFile));

        // Prepare rectify map:
        timlog.enter("rectifyMap.setFromCamParams");
        rectifyMap.setFromCamParams(params);
        timlog.leave("rectifyMap.setFromCamParams");
    }

    // Show to the user a list of possible camera drivers and creates and open
    // the selected camera.
    cout << "Please, select the input stereo camera or rawlog file (with "
            "stereo images)...\n";

    mrpt::hwdrivers::CCameraSensor::Ptr cam =
        mrpt::hwdrivers::prepareVideoSourceFromUserSelection();
    if (!cam) return;

    cout << "Video stream open OK\n";

    // Create 3D window:
    CDisplayWindow3D win("Demo of stereo rectification", 1280, 600);

    // Create 2 viewports, one for each image:
    std::vector<Viewport::Ptr> gl_views(2);
    {
        Scene::Ptr& theScene = win.get3DSceneAndLock();
        gl_views[0] = theScene->getViewport("main");
        ASSERT_(gl_views[0]);
        gl_views[1] = theScene->createViewport("right_image");

        // Assign sizes:
        gl_views[0]->setViewportPosition(0, 0, .5, 1.);
        gl_views[1]->setViewportPosition(.5, 0, .5, 1.);

        // IMPORTANT!!! IF NOT UNLOCKED, THE WINDOW WILL NOT BE UPDATED!
        win.unlockAccess3DScene();
    }

    win.setPos(10, 10);
    //  win.addTextMessage(...

    bool enable_rectify = true;
    bool enable_draw_epipolar_lines = true;
    CImage img_left_rectified,
        img_right_rectified;  // Declared here to serve as a memory buffer
    // (avoid deallocating/allocating)

    cout << "Close the window to end.\n";
    while (win.isOpen())
    {
        win.addTextMessage(5, 5, format("%.02fFPS", win.getRenderingFPS()), 0);
        win.addTextMessage(
            5, 25,
            format(
                "'r': Switch rectify (Now is: %s) | '+'/'-': Modify "
                "alpha (Now is: %.02f)",
                enable_rectify ? "ON" : "OFF", rectifyMap.getAlpha()),
            10);
        win.addTextMessage(
            5, 50,
            format(
                "'s': Switch resize output to 320x240 (Now is: %s) | 'c': "
                "Switch no-disparity (Now is: %s) | 'e': Switch epipolar lines",
                rectifyMap.isEnabledResizeOutput() ? "ON" : "OFF",
                rectifyMap.isEnabledBothCentersCoincide() ? "ON" : "OFF"),
            11);

        std::this_thread::sleep_for(1ms);

        // Grab new video frame:
        CObservation::Ptr obs = cam->getNextFrame();
        if (obs)
        {
            if (IS_CLASS(*obs, CObservationStereoImages))
            {
                // Get the observation object:
                CObservationStereoImages::Ptr o =
                    std::dynamic_pointer_cast<CObservationStereoImages>(obs);

                // If the rectification maps are still not ready, prepare them
                // now:
                if (!rectifyMap.isSet())
                {
                    timlog.enter("rectifyMap.setFromCamParams");
                    rectifyMap.setFromCamParams(*o);
                    timlog.leave("rectifyMap.setFromCamParams");

                    /*mrpt::img::TStereoCamera params;
                    o->getStereoCameraParams(params);
                    cout << params.dumpAsText() << endl;*/
                }

                win.get3DSceneAndLock();

                if (enable_rectify)
                {
                    // Rectify:
                    timlog.enter("rectifyMap.rectify()");

                    rectifyMap.rectify(
                        o->imageLeft, o->imageRight, img_left_rectified,
                        img_right_rectified);

                    timlog.leave("rectifyMap.rectify()");
                }
                else
                {
                    // Don't rectify:
                    img_left_rectified = o->imageLeft;
                    img_right_rectified = o->imageRight;
                }

                // Draw lines:
                if (enable_draw_epipolar_lines)
                {
                    const unsigned int LINES_SEP = 40;
                    const unsigned int w = img_left_rectified.getWidth();
                    const unsigned int h = img_left_rectified.getHeight();
                    for (unsigned int y = 0; y < h; y += LINES_SEP)
                    {
                        img_left_rectified.line(
                            0, y, w - 1, y, mrpt::img::TColor::red(), 2);
                        img_right_rectified.line(
                            0, y, w - 1, y, mrpt::img::TColor::red(), 2);
                    }
                }

                gl_views[0]->setImageView(img_left_rectified);
                gl_views[1]->setImageView(img_right_rectified);

                win.addTextMessage(
                    150, 5, mrpt::system::timeToString(o->timestamp), 2);

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

            if (win.keyHit())
            {
                mrptKeyModifier kmods;
                int key = win.getPushedKey(&kmods);

                if (key == MRPTK_ESCAPE) break;
                if (key == 'r' || key == 'R') enable_rectify = !enable_rectify;
                if (key == 'e' || key == 'E')
                    enable_draw_epipolar_lines = !enable_draw_epipolar_lines;
                if (key == '+' || key == '-')
                {
                    double alpha =
                        rectifyMap.getAlpha() + (key == '-' ? -0.1 : 0.1);
                    alpha = std::min(1., std::max(0., alpha));
                    rectifyMap.setAlpha(alpha);
                }
                if (key == 's' || key == 'S')
                {
                    rectifyMap.enableResizeOutput(
                        !rectifyMap.isEnabledResizeOutput(), 320, 240);
                }
                if (key == 'c' || key == 'C')
                {
                    rectifyMap.enableBothCentersCoincide(
                        !rectifyMap.isEnabledBothCentersCoincide());
                }
            }
        }
    }
}

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