OpenCV fisheye undistort issues

问题

EDIT: I found the cause of the problem, the fisheye::undistortImage() function was not working correctly, I replaced it with estimateNewCameraMatrixForUndistortRectify(), initUndistortRectifyMap(), and remap() as in the original calibrate camera example. Not perfect yet but going in the right direction. Output image: http://imgur.com/a/Xm5vq

        Mat output;
        Mat newK;
        Mat view, map1, map2;

        Size newSize(1200, 1200);
        Mat rview(newSize, frame.type());
        //resize(rview, rview, newSize);

        fisheye::estimateNewCameraMatrixForUndistortRectify(K, D, frame.size(), Matx33d::eye(), newK, 1);

        fisheye::initUndistortRectifyMap(K, D, Matx33d::eye(), newK, frame.size(), CV_16SC2, map1, map2);

        //fisheye::undistortImage(frame, output, K, D, identity);

        remap(frame, rview, map1, map2, INTER_LINEAR);

        imshow("Image View", rview);
        imshow(window_name, frame);

        if (waitKey(50) == 27) {
            break;
        }

Original post: I'm trying to calibrate and undistort an image coming from an 180 degree fisheye USB camera. Most of this code is from existing examples that claim to be functional.

The code runs fine until fisheye::undistortImage where the output image is very distorted and centered around the top left corner of the window.

Screen shot of the "undistorted" chess board and calibration matrix outputs - http://imgur.com/a/RTIoT

What am I missing here?

int main(int argc, char** argv) {
    VideoCapture camera;
    camera.open(1);
    if (!camera.isOpened()) {
        cout << "Failed to open camera." << std::endl;
        return -1;
    }

    double fWidth = camera.get(CAP_PROP_FRAME_WIDTH);
    double fHeight = camera.get(CAP_PROP_FRAME_HEIGHT);
    cout << fWidth << std::endl;
    cout << fHeight << std::endl;

    /*
    640 320
    480 240
    */

    const char* window_name = "output";
    namedWindow(window_name, WINDOW_NORMAL);

    Mat frame;
    Size boardSize;
    boardSize.width = 9;
    boardSize.height = 6;

    int remaining_frames = 30;

    Mat K;//  = Mat(3, 3, CV_64F, vK);
    Mat D;
    Mat identity = Mat::eye(3, 3, CV_64F);

    vector<vector<Point2f> > img_points;
    vector<vector<Point3f> > obj_points(1);

    int sq_sz = 25;

    for (int i = 0; i < boardSize.height; i++) {
        for (int j = 0; j < boardSize.width; j++) {
            obj_points[0].push_back(Point3f(float(j * sq_sz), float(i * sq_sz), 0));
        }
    }

    obj_points.resize(remaining_frames, obj_points[0]);

    bool found = false;

    clock_t prevTimestamp = 0;
    int delay = 500;

    while (1) {

        frame = nextFrame(camera);

        bool blinkOutput = false;

        if (remaining_frames > 0) {
            vector<Point2f> corners;
            int chessBoardFlags = CALIB_CB_ADAPTIVE_THRESH + CALIB_CB_NORMALIZE_IMAGE;


            found = findChessboardCorners(frame, boardSize, corners, chessBoardFlags);


            if (found) {
                drawChessboardCorners(frame, boardSize, corners, found);
                if (clock() - prevTimestamp > delay*1e-3*CLOCKS_PER_SEC) {

                    Mat viewGray;
                    cvtColor(frame, viewGray, COLOR_BGR2GRAY);
                    cornerSubPix(viewGray, corners, Size(11, 11), Size(-1, -1), TermCriteria(TermCriteria::EPS + TermCriteria::COUNT, 30, 0.1));

                    img_points.push_back(corners);
                    remaining_frames--;
                    cout << remaining_frames << " frames to calibration." << endl;
                    blinkOutput = true;
                    prevTimestamp = clock();
                }

                if (remaining_frames == 0) {
                    cout << "Computing distortion" << endl;

                    int flags = 0;
                    flags |= cv::fisheye::CALIB_RECOMPUTE_EXTRINSIC;
                    flags |= cv::fisheye::CALIB_CHECK_COND;
                    flags |= cv::fisheye::CALIB_FIX_SKEW;


                    fisheye::calibrate(obj_points, img_points, frame.size(), K, D, noArray(), noArray(), flags);
                    cout << "Finished computing distortion" << endl;
                    cout << K << endl;
                    cout << D << endl;
                }
            }

            if (blinkOutput) { bitwise_not(frame, frame); }
            cv::imshow(window_name, frame);
            if (waitKey(50) == 27) {
                break;
            }
        }
        else {
            Mat output;

            fisheye::undistortImage(frame, output, K, D, identity);

            cv::imshow(window_name, output);
            if (waitKey(50) == 27) {
                break;
            }
        }


    }

    return 0;
}

来源：https://stackoverflow.com/questions/38983164/opencv-fisheye-undistort-issues