如何獲取具有已知內部參數的外部攝像機參數

Question

我已經使用opencv完成了攝像機的校準並獲得了很好的內部參數。但是我沒有使用cvFindExtrinsicParams2和cv :: solvePnP函數來查找我的相機的外部參數。這裏是我的代碼：

#include <iostream> 
#include<opencv\cv.h> 
#include <opencv2/highgui/highgui.hpp> 

using namespace cv; 
using namespace std; 

int n_boards = 0; 
const int board_dt = 20; 
int board_w; 
int board_h; 

int main(int argc, char* argv[]) 
{ 
board_w = 6; // Board width in squares 
board_h = 9; // Board height 
n_boards = 15; // Number of boards 
int board_n = board_w * board_h; 
CvSize board_sz = cvSize(board_w, board_h); 
CvCapture* capture = cvCreateCameraCapture(0); 
assert(capture); 

cvNamedWindow("Calibration"); 
// Allocate Sotrage 
CvMat* image_points   = cvCreateMat(n_boards*board_n, 2, CV_32FC1); 
CvMat* object_points  = cvCreateMat(n_boards*board_n, 3, CV_32FC1); 
CvMat* point_counts   = cvCreateMat(n_boards, 1, CV_32SC1); 
CvMat* intrinsic_matrix  = cvCreateMat(3, 3, CV_32FC1); 
CvMat* extrinsic_matrix  = cvCreateMat(3, 4, CV_32FC1); 
CvMat* distortion_coeffs = cvCreateMat(5, 1, CV_32FC1); 
CvMat* rvec     =cvCreateMat(1, 3, CV_32FC1); 
CvMat* tvec     = cvCreateMat(3, 1, CV_32FC1); 
CvMat* rotmat    = cvCreateMat(3, 3, CV_32FC1); 

CvPoint2D32f* corners = new CvPoint2D32f[ board_n ]; 
int corner_count; 
int successes = 0; 
int step, frame = 0; 

IplImage *image = cvQueryFrame(capture); 
IplImage *gray_image = cvCreateImage(cvGetSize(image), 8, 1); 

// Capture Corner views loop until we've got n_boards 
// succesful captures (all corners on the board are found) 

while(successes < n_boards){ 
    // Skp every board_dt frames to allow user to move chessboard 
    if(frame++ % board_dt == 0){ 
     // Find chessboard corners: 

    int found = cvFindChessboardCorners(image, board_sz, corners, 
&corner_count, CV_CALIB_CB_ADAPTIVE_THRESH |   CV_CALIB_CB_FILTER_QUADS); 

     // Get subpixel accuracy on those corners 
     cvCvtColor(image, gray_image, CV_BGR2GRAY); 
    cvFindCornerSubPix(gray_image, corners, corner_count, cvSize(11, 11), 
cvSize(-1, -1), cvTermCriteria(CV_TERMCRIT_EPS+CV_TERMCRIT_ITER, 30, 0.1)); 

     // Draw it 
    cvDrawChessboardCorners(image, board_sz, corners, corner_count, found); 
     cvShowImage("Calibration", image); 

     // If we got a good board, add it to our data 
     if(corner_count == board_n){ 
      step = successes*board_n; 
     or(int i=step, j=0; j < board_n; ++i, ++j){ 
      CV_MAT_ELEM(*image_points, float, i, 0) = corners[j].x; 
    CV_MAT_ELEM(*image_points, float, i, 1) = corners[j].y; 
     CV_MAT_ELEM(*object_points, float, i, 0) = j/board_w; 
      CV_MAT_ELEM(*object_points, float, i, 1) = j%board_w; 
       CV_MAT_ELEM(*object_points, float, i, 2) = 0.0f; 
      } 
      CV_MAT_ELEM(*point_counts, int, successes, 0) = board_n; 
      successes++; 
     } 
    } 

    // Handle pause/unpause and ESC 
    int c = cvWaitKey(15); 
    if(c == 'p'){ 
     c = 0; 
     while(c != 'p' && c != 27){ 
      c = cvWaitKey(250); 
     } 
    } 
    if(c == 27) 
     return 0; 
    image = cvQueryFrame(capture); // Get next image 
} // End collection while loop 

// Allocate matrices according to how many chessboards found 
CvMat* object_points2 = cvCreateMat(successes*board_n, 3, CV_32FC1); 
CvMat* image_points2 = cvCreateMat(successes*board_n, 2, CV_32FC1); 
CvMat* point_counts2 = cvCreateMat(successes, 1, CV_32SC1); 

// Transfer the points into the correct size matrices 
for(int i = 0; i < successes*board_n; ++i){ 
CV_MAT_ELEM(*image_points2, float, i, 0) = CV_MAT_ELEM(*image_points, float, i, 0); 
CV_MAT_ELEM(*image_points2, float, i, 1) = CV_MAT_ELEM(*image_points, float, i, 1); 
CV_MAT_ELEM(*object_points2, float, i, 0) = CV_MAT_ELEM(*object_points,float, i, 0); 
CV_MAT_ELEM(*object_points2, float, i, 1) = CV_MAT_ELEM(*object_points, float, i,1); 
CV_MAT_ELEM(*object_points2, float, i, 2) = CV_MAT_ELEM(*object_points, float, i,2); 
} 

for(int i=0; i < successes; ++i){ 
CV_MAT_ELEM(*point_counts2, int, i, 0) = CV_MAT_ELEM(*point_counts, int, i, 0); 
} 
cvReleaseMat(&object_points); 
cvReleaseMat(&image_points); 
cvReleaseMat(&point_counts); 

// At this point we have all the chessboard corners we need 
// Initiliazie the intrinsic matrix such that the two focal lengths 
// have a ratio of 1.0 

CV_MAT_ELEM(*intrinsic_matrix, float, 0, 0) = 1.0; 
CV_MAT_ELEM(*intrinsic_matrix, float, 1, 1) = 1.0; 


cvCalibrateCamera2(object_points2, image_points2, 
point_counts2, cvGetSize(image), intrinsic_matrix, 
distortion_coeffs, NULL, 
    NULL, CV_CALIB_FIX_ASPECT_RATIO); 

// Save the intrinsics and distortions 
cvSave("Intrinsics.xml", intrinsic_matrix); 
cvSave("Distortion.xml", distortion_coeffs); 

// Example of loading these matrices back in 
CvMat *intrinsic = (CvMat*)cvLoad("Intrinsics.xml"); 
CvMat *distortion = (CvMat*)cvLoad("Distortion.xml"); 

// Build the undistort map that we will use for all subsequent frames 
IplImage* mapx = cvCreateImage(cvGetSize(image), IPL_DEPTH_32F, 1); 
IplImage* mapy = cvCreateImage(cvGetSize(image), IPL_DEPTH_32F, 1); 
cvInitUndistortMap(intrinsic, distortion, mapx, mapy); 


//Extrinsic parameters 

//CV_MAT_ELEM(*extrinsic_matrix, float, 0, 0) = 1.0; 
//CV_MAT_ELEM(*extrinsic_matrix, float, 1, 1) = 1.0; 
cvFindExtrinsicCameraParams2(object_points2,image_points2, 
intrinsic_matrix,distortion_coeffs,rvec,tvec); 

//convert the rotation matrix into a rotation vector 
cvRodrigues2(rvec,rotmat,0); 

// Save the intrinsics and distortions 
cvSave("Extrinsics.xml", extrinsic_matrix); 

// Example of loading these matrices back in 
CvMat *Extrinsic = (CvMat*)cvLoad("Extrinsics.xml"); 


// Run the camera to the screen, now showing the raw and undistorted image 
cvNamedWindow("Undistort"); 

while(image){ 
    IplImage *t = cvCloneImage(image); 
    cvShowImage("Calibration", image); // Show raw image 
    cvRemap(t, image, mapx, mapy); // undistort image 
    cvReleaseImage(&t); 
    cvShowImage("Undistort", image); // Show corrected image 

    // Handle pause/unpause and esc 
    int c = cvWaitKey(15); 
    if(c == 'p'){ 
     c = 0; 
     while(c != 'p' && c != 27) 
     { 
      c = cvWaitKey(250); 
     } 
    } 
    if(c == 27) 
     break; 
    image = cvQueryFrame(capture); 
} 

return 0; 
} 

Answer 1

extrinsic_matrix = cvFindExtrinsicCameraParams2(object_points2,image_points2, intrinsic_matrix,distortion_coeffs,rvec,tvec);