checkerboard_cam_calib.cpp

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/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file        |
   | See: http://www.mrpt.org/Authors - All rights reserved.                   |
   | Released under BSD License. See details in http://www.mrpt.org/License    |
   +---------------------------------------------------------------------------+ */

#include "vision-precomp.h"   // Precompiled headers

#include <mrpt/system/filesystem.h>
#include <mrpt/utils/CConfigFileMemory.h>

#include <mrpt/vision/chessboard_find_corners.h>
#include <mrpt/vision/pinhole.h>
#include <mrpt/vision/chessboard_camera_calib.h>

// Universal include for all versions of OpenCV
#include <mrpt/otherlibs/do_opencv_includes.h>

using namespace mrpt;
using namespace mrpt::vision;
using namespace mrpt::utils;
using namespace mrpt::math;
using namespace mrpt::poses;
using namespace std;

/* -------------------------------------------------------
                                checkerBoardCameraCalibration
   ------------------------------------------------------- */
bool mrpt::vision::checkerBoardCameraCalibration(
        TCalibrationImageList &images,
        unsigned int  check_size_x,
        unsigned int  check_size_y,
        double        check_squares_length_X_meters,
        double        check_squares_length_Y_meters,
        CMatrixDouble33                 &intrinsicParams,
        std::vector<double>             &distortionParams,
        bool                                    normalize_image,
        double            *out_MSE,
        bool               skipDrawDetectedImgs,
        bool                       useScaramuzzaAlternativeDetector
        )
{
        // Just a wrapper for the newer version of the function which uses TCamera:
        TCamera  cam;
        bool ret = checkerBoardCameraCalibration(
                images,
                check_size_x,check_size_y,
                check_squares_length_X_meters, check_squares_length_Y_meters,
                cam,
                normalize_image,
                out_MSE,skipDrawDetectedImgs,
                useScaramuzzaAlternativeDetector);

        intrinsicParams = cam.intrinsicParams;
        distortionParams = cam.getDistortionParamsAsVector();
        return ret;
}

#if MRPT_HAS_OPENCV
// JL says:  This was copied here since it seems OpenCV 2.3 had a broken <opencv2/core/eigen.hpp> header.
//  It should be removed in the future when 2.3 becomes too old to support.
namespace cv {
template<typename _Tp, int _rows, int _cols, int _options, int _maxRows, int _maxCols>
void my_cv2eigen( const Mat& src,
                           Eigen::Matrix<_Tp, _rows, _cols, _options, _maxRows, _maxCols>& dst )
{
        CV_DbgAssert(src.rows == _rows && src.cols == _cols);
        if( !(dst.Flags & Eigen::RowMajorBit) )
        {
                Mat _dst(src.cols, src.rows, DataType<_Tp>::type,
                                 dst.data(), (size_t)(dst.stride()*sizeof(_Tp)));
                if( src.type() == _dst.type() )
                        transpose(src, _dst);
                else if( src.cols == src.rows )
                {
                        src.convertTo(_dst, _dst.type());
                        transpose(_dst, _dst);
                }
                else
                        Mat(src.t()).convertTo(_dst, _dst.type());
                CV_DbgAssert(_dst.data == (uchar*)dst.data());
        }
        else
        {
                Mat _dst(src.rows, src.cols, DataType<_Tp>::type,
                                 dst.data(), (size_t)(dst.stride()*sizeof(_Tp)));
                src.convertTo(_dst, _dst.type());
                CV_DbgAssert(_dst.data == (uchar*)dst.data());
        }
}
}
#endif

/* -------------------------------------------------------
                                checkerBoardCameraCalibration
   ------------------------------------------------------- */
bool mrpt::vision::checkerBoardCameraCalibration(
        TCalibrationImageList &images,
        unsigned int  check_size_x,
        unsigned int  check_size_y,
        double        check_squares_length_X_meters,
        double        check_squares_length_Y_meters,
        mrpt::utils::TCamera    &out_camera_params,
        bool                                    normalize_image,
        double            *out_MSE,
        bool               skipDrawDetectedImgs,
        bool                       useScaramuzzaAlternativeDetector
        )
{
        MRPT_UNUSED_PARAM(skipDrawDetectedImgs);
#if MRPT_HAS_OPENCV
        try
        {
                ASSERT_(check_size_x>2)
                ASSERT_(check_size_y>2)
                ASSERT_(check_squares_length_X_meters>0)
                ASSERT_(check_squares_length_Y_meters>0)

                if (images.size()<1)
                {
                        std::cout << "ERROR: No input images." << std::endl;
                        return false;
                }

                const unsigned CORNERS_COUNT = check_size_x * check_size_y;
                const CvSize check_size = cvSize(check_size_x, check_size_y);

                // Fill the pattern of expected pattern points only once out of the loop:
                vector<cv::Point3f> pattern_obj_points(CORNERS_COUNT);
                {
                        unsigned int y,k;
                        for( y = 0, k = 0; y < check_size_y; y++ )
                        {
                                for( unsigned int x = 0; x < check_size_x; x++, k++ )
                                {
                                        pattern_obj_points[k].x =-check_squares_length_X_meters * x;  // The "-" is for convenience, so the camera poses appear with Z>0
                                        pattern_obj_points[k].y = check_squares_length_Y_meters * y;
                                        pattern_obj_points[k].z = 0;
                                }
                        }
                }

                // First: Assure all images are loaded:
                // -------------------------------------------
                TCalibrationImageList::iterator it;
                for (it=images.begin();it!=images.end();++it)
                {
                        TImageCalibData &dat = it->second;

                        dat.projectedPoints_distorted.clear();  // Clear reprojected points.
                        dat.projectedPoints_undistorted.clear();

                        // Skip if images are marked as "externalStorage":
                        if (!dat.img_original.isExternallyStored() && !mrpt::system::extractFileExtension(it->first).empty()  )
                        {
                                if (!dat.img_original.loadFromFile(it->first))
                                        THROW_EXCEPTION_FMT("Error reading image: %s",it->first.c_str());

                                dat.img_checkboard = dat.img_original;
                                dat.img_rectified  = dat.img_original;
                        }
                }

                // For each image, find checkerboard corners:
                // -----------------------------------------------
                vector<vector<cv::Point3f> > objectPoints;  // final container for detected stuff
                vector<vector<cv::Point2f> > imagePoints;   // final container for detected stuff

                unsigned int  valid_detected_imgs = 0;
                vector<string>   pointsIdx2imageFile;
                cv::Size imgSize(0,0);

                unsigned int i;
                for (i=0,it=images.begin();it!=images.end();it++,i++)
                {
                        TImageCalibData &dat = it->second;

                        // Make grayscale version:
                        const CImage img_gray( dat.img_original, FAST_REF_OR_CONVERT_TO_GRAY );

                        if (!i)
                        {
                                imgSize = cv::Size(img_gray.getWidth(),img_gray.getHeight() );
                                out_camera_params.ncols = imgSize.width;
                                out_camera_params.nrows = imgSize.height;
                        }
                        else
                        {
                                if (imgSize.height != (int)img_gray.getHeight() || imgSize.width != (int)img_gray.getWidth())
                                {
                                        std::cout << "ERROR: All the images must have the same size" << std::endl;
                                        return false;
                                }
                        }

                        // Try with expanded versions of the image if it fails to detect the checkerboard:
                        unsigned corners_count;
                        bool corners_found=false;

                        corners_count = CORNERS_COUNT;

                        vector<cv::Point2f> this_img_pts(CORNERS_COUNT);  // Temporary buffer for points, to be added if the points pass the checks.

                        dat.detected_corners.clear();

                        // Do detection (this includes the "refine corners" with cvFindCornerSubPix):
                        vector<TPixelCoordf> detectedCoords;
                        corners_found = mrpt::vision::findChessboardCorners(
                                img_gray,
                                detectedCoords,
                                check_size_x,check_size_y,
                                normalize_image, // normalize_image
                                useScaramuzzaAlternativeDetector
                                );

                        corners_count = detectedCoords.size();

                        // Copy the data into the overall array of coords:
                        ASSERT_(detectedCoords.size()<=CORNERS_COUNT);
                        for (size_t p=0;p<detectedCoords.size();p++)
                        {
                                this_img_pts[p].x = detectedCoords[p].x;
                                this_img_pts[p].y = detectedCoords[p].y;
                        }

                        if (corners_found && corners_count!=CORNERS_COUNT)
                                corners_found = false;

                        cout << format("Img %s: %s\n", mrpt::system::extractFileName(it->first).c_str() , corners_found ? "DETECTED" : "NOT DETECTED" );

                        if( corners_found )
                        {
                                // save the corners in the data structure:
                                int x, y;
                                unsigned int k;
                                for( y = 0, k = 0; y < check_size.height; y++ )
                                        for( x = 0; x < check_size.width; x++, k++ )
                                                dat.detected_corners.push_back( mrpt::utils::TPixelCoordf( this_img_pts[k].x, this_img_pts[k].y ) );

                                // Draw the checkerboard in the corresponding image:
                                // ----------------------------------------------------
                                if ( !dat.img_original.isExternallyStored() )
                                {
                                        const int r = 4;
                                        CvPoint prev_pt= cvPoint(0, 0);
                                        const int line_max = 8;
                                        CvScalar line_colors[8];

                                        line_colors[0] = CV_RGB(255,0,0);
                                        line_colors[1] = CV_RGB(255,128,0);
                                        line_colors[2] = CV_RGB(255,128,0);
                                        line_colors[3] = CV_RGB(200,200,0);
                                        line_colors[4] = CV_RGB(0,255,0);
                                        line_colors[5] = CV_RGB(0,200,200);
                                        line_colors[6] = CV_RGB(0,0,255);
                                        line_colors[7] = CV_RGB(255,0,255);

                                        // Checkboad as color image:
                                        dat.img_original.colorImage( dat.img_checkboard );

                                        void *rgb_img = dat.img_checkboard.getAs<IplImage>();

                                        for( y = 0, k = 0; y < check_size.height; y++ )
                                        {
                                                CvScalar color = line_colors[y % line_max];
                                                for( x = 0; x < check_size.width; x++, k++ )
                                                {
                                                        CvPoint pt;
                                                        pt.x = cvRound(this_img_pts[k].x);
                                                        pt.y = cvRound(this_img_pts[k].y);

                                                        if( k != 0 ) cvLine( rgb_img, prev_pt, pt, color );

                                                        cvLine( rgb_img,
                                                                          cvPoint( pt.x - r, pt.y - r ),
                                                                          cvPoint( pt.x + r, pt.y + r ), color );
                                                        cvLine( rgb_img,
                                                                          cvPoint( pt.x - r, pt.y + r),
                                                                          cvPoint( pt.x + r, pt.y - r), color );
                                                        cvCircle( rgb_img, pt, r+1, color );
                                                        prev_pt = pt;
                                                }
                                        }
                                }

                                // Accept this image as good:
                                pointsIdx2imageFile.push_back( it->first );
                                imagePoints.push_back( this_img_pts );
                                objectPoints.push_back( pattern_obj_points );

                                valid_detected_imgs++;
                        }

                } // end find corners

                std::cout << valid_detected_imgs << " valid images." << std::endl;
                if (!valid_detected_imgs)
                {
                        std::cout << "ERROR: No valid images. Perhaps the checkerboard size is incorrect?" << std::endl;
                        return false;
                }

                // ---------------------------------------------
                // Calculate the camera parameters
                // ---------------------------------------------
                // Calibrate camera
                cv::Mat cameraMatrix, distCoeffs(1,5,CV_64F,cv::Scalar::all(0));
                vector<cv::Mat> rvecs, tvecs;

                const double cv_calib_err = 
                cv::calibrateCamera(
                        objectPoints,imagePoints,imgSize,
                        cameraMatrix, distCoeffs, rvecs, tvecs,
                        0 /*flags*/ );

                // Load matrix:
                out_camera_params.intrinsicParams = CMatrixDouble33( cameraMatrix.ptr<double>() );

                out_camera_params.dist.assign(0);
                for (int i=0;i<5;i++)
                        out_camera_params.dist[i] = distCoeffs.ptr<double>()[i];

                // Load camera poses:
                for (i=0;i<valid_detected_imgs;i++)
                {
                        CMatrixDouble44 HM;
                        HM.zeros();
                        HM(3,3)=1;

                        {
                                // Convert rotation vectors -> rot matrices:
                                cv::Mat cv_rot;
                                cv::Rodrigues(rvecs[i],cv_rot);

                                Eigen::Matrix3d rot;
                                cv::my_cv2eigen(cv_rot, rot );
                                HM.block<3,3>(0,0) = rot;
                        }

                        {
                                Eigen::Matrix<double,3,1> trans;
                                cv::my_cv2eigen(tvecs[i], trans );
                                HM.block<3,1>(0,3) = trans;
                        }

                        CPose3D p = CPose3D(0,0,0) - CPose3D(HM);

                        images[ pointsIdx2imageFile[i] ].reconstructed_camera_pose = p;

                        std::cout << "Img: " <<  mrpt::system::extractFileName(pointsIdx2imageFile[i])  << ": " << p << std::endl;
                }

                {
                        CConfigFileMemory cfg;
                        out_camera_params.saveToConfigFile("CAMERA_PARAMS",cfg);
                        std::cout << cfg.getContent() << std::endl;
                }

                // ----------------------------------------
                // Undistort images:
                // ----------------------------------------
                for (it=images.begin();it!=images.end();++it)
                {
                        TImageCalibData &dat = it->second;
                        if (!dat.img_original.isExternallyStored())
                                dat.img_original.rectifyImage( dat.img_rectified, out_camera_params);
                } // end undistort

                // -----------------------------------------------
                // Reproject points to measure the fit sqr error
                // -----------------------------------------------
                double sqrErr = 0;

                for (i=0;i<valid_detected_imgs;i++)
                {
                        TImageCalibData  & dat = images[ pointsIdx2imageFile[i] ];
                        if (dat.detected_corners.size()!=CORNERS_COUNT) continue;

                        // Reproject all the points into pixel coordinates:
                        // -----------------------------------------------------
                        vector<TPoint3D>  lstPatternPoints(CORNERS_COUNT);      // Points as seen from the camera:
                        for (unsigned int p=0;p<CORNERS_COUNT;p++)
                                lstPatternPoints[p] = TPoint3D(pattern_obj_points[p].x,pattern_obj_points[p].y,pattern_obj_points[p].z);

                        vector<TPixelCoordf>    &projectedPoints = dat.projectedPoints_undistorted;
                        vector<TPixelCoordf>    &projectedPoints_distorted = dat.projectedPoints_distorted;

                        vision::pinhole::projectPoints_no_distortion(
                                lstPatternPoints, // Input points
                                dat.reconstructed_camera_pose,
                                out_camera_params.intrinsicParams, // calib matrix
                                projectedPoints  // Output points in pixels
                                );

                        vision::pinhole::projectPoints_with_distortion(
                                lstPatternPoints, // Input points
                                dat.reconstructed_camera_pose,
                                out_camera_params.intrinsicParams, // calib matrix
                                out_camera_params.getDistortionParamsAsVector(),
                                projectedPoints_distorted// Output points in pixels
                                );

                        ASSERT_(projectedPoints.size()==CORNERS_COUNT);
                        ASSERT_(projectedPoints_distorted.size()==CORNERS_COUNT);


                        for (unsigned int p=0;p<CORNERS_COUNT;p++)
                        {
                                const double px = projectedPoints[p].x;
                                const double py = projectedPoints[p].y;

                                const double px_d = projectedPoints_distorted[p].x;
                                const double py_d = projectedPoints_distorted[p].y;

                                // Only draw if the img is NOT external:
                                if (!dat.img_original.isExternallyStored())
                                {
                                        if( px >= 0 && px < imgSize.width && py >= 0 && py < imgSize.height )
                                                cvCircle( dat.img_rectified.getAs<IplImage>(), cvPoint(px,py), 4, CV_RGB(0,0,255) );
                                }

                                // Accumulate error:
                                sqrErr+=square(px_d-dat.detected_corners[p].x)+square(py_d-dat.detected_corners[p].y); // Error relative to the original (distorted) image.
                        }
                }

                if (valid_detected_imgs)
                {
                        sqrErr /= CORNERS_COUNT*valid_detected_imgs;
                        std::cout << "Average err. of reprojection: " << sqrt(sqrErr) << " pixels (OpenCV error=" << cv_calib_err << ")\n";
                }
                if(out_MSE) *out_MSE = sqrt(sqrErr);

                return true;
        }
        catch(std::exception &e)
        {
                std::cout << e.what() << std::endl;
                return false;
        }
#else
        THROW_EXCEPTION("Function not available: MRPT was compiled without OpenCV")
#endif
}