使用opencv进行双目相机标定

一、利用相机拍摄保存相片

拍摄保存想拍摄棋盘局相片，用来做相机标定。

#include
#include
using namespace cv;
using namespace std;

void main()
{
	VideoCapture cap;
	cap.open(0); //打开摄像头
	if (!cap.isOpened())//如果视频不能正常打开则返回
		return;
	cvWaitKey(30);
	Mat frame;//用于保存每一帧图像
	cap >> frame;
	imshow("【双目原始视图】", frame);
	cvWaitKey(300);

	char buf[30] = { 0 }; //保存路径变量

	while (1)
	{
		cap >> frame;          //等价于cap.read(frame);
		if (frame.empty())     //如果某帧为空则退出循环
			break;

		imshow("【双目原始视图】", frame);    //显示双目原始图像  原始分辨率为 640*480

		Mat DoubleImage;

		resize(frame, DoubleImage, Size(640, 240), (0, 0), (0, 0), INTER_AREA);   // 纵向分辨率缩小一半
		imshow("【双目缩小视图】", DoubleImage);  //显示图像


		Mat	LeftImage = DoubleImage(Rect(0, 0, 320, 240));      //分割得到左视图
		Mat RightImage = DoubleImage(Rect(320, 0, 320, 240));   //分割得到右视图

		imshow("【左视图】", LeftImage);         //显示左视图
		imshow("【右视图】", RightImage);        //显示右视图

		char c = cvWaitKey(30);
		if (c == 27)//Esc键退出
		{
			break;
		}

		static int i = 9;
		if (13 == char(c))
		{
			sprintf(buf, ".\\picture\\left_%d.png", i);  //保存左视图
			cout << buf;
			imwrite(buf, LeftImage);



			sprintf(buf, ".\\picture\\right_%d.png", i);  //保存右视图
			imwrite(buf, RightImage);



			sprintf(buf, ".\\picture\\total_%d.png", i);  //保存整体图像
			imwrite(buf, DoubleImage);
			i++;
		}

	}
	cap.release();//释放资源
}

二、相机标定

注意stereo_calibration.xml放置目录要准确，保证上一步骤拍摄的相片能够读到。

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include
#include

//此处参数需要根据棋盘格个数修改    
//例如 黑白棋盘格 宽（w）为10个棋盘格 那么 w 为 10 -1 = 9
#define  w  9      //棋盘格宽的黑白交叉点个数    
#define  h  6      //棋盘格高的黑白交叉点个数    

const  float chessboardSquareSize = 12.5f;  //每个棋盘格方块的边长 单位 为 mm


using namespace std;
using namespace cv;


//从 xml 文件中读取图片存储路径 

static bool readStringList(const string& filename, vector& list)
{
	list.resize(0);
	FileStorage fs(filename, FileStorage::READ);
	if (!fs.isOpened())
		return false;
	FileNode n = fs.getFirstTopLevelNode();
	if (n.type() != FileNode::SEQ)
		return false;
	FileNodeIterator it = n.begin(), it_end = n.end();
	for (; it != it_end; ++it)
		list.push_back((string)*it);
	return true;
}

//记录棋盘格角点个数

static void calcChessboardCorners(Size boardSize, float squareSize, vector& corners)
{
	corners.resize(0);
	for (int i = 0; i < boardSize.height; i++)        //height和width位置不能颠倒
		for (int j = 0; j < boardSize.width; j++)
		{
			corners.push_back(Point3f(j * squareSize, i * squareSize, 0));
		}
}


bool calibrate(Mat& intrMat, Mat& distCoeffs, vector>& imagePoints,
	vector>& ObjectPoints, Size& imageSize, const int cameraId,
	vector imageList)
{

	double rms = 0;  //重投影误差

	Size boardSize;
	boardSize.width = w;
	boardSize.height = h;

	vector pointBuf;
	float squareSize = chessboardSquareSize;

	vector rvecs, tvecs; //定义两个摄像头的旋转矩阵 和平移向量

	bool ok = false;

	int nImages = (int)imageList.size() / 2;
	cout << "图片张数" << nImages;
	namedWindow("View", 1);

	int nums = 0; //有效棋盘格图片张数

	for (int i = 0; i < nImages; i++)
	{
		Mat view, viewGray;
		view = imread(imageList[i * 2 + cameraId], 1); //读取图片
		imageSize = view.size();
		cvtColor(view, viewGray, COLOR_BGR2GRAY); //转化成灰度图

		bool found = findChessboardCorners(view, boardSize, pointBuf,
			CV_CALIB_CB_ADAPTIVE_THRESH | CV_CALIB_CB_FAST_CHECK | CV_CALIB_CB_NORMALIZE_IMAGE);  //寻找棋盘格角点

		if (found)
		{
			nums++;
			cornerSubPix(viewGray, pointBuf, Size(11, 11),
				Size(-1, -1), TermCriteria(CV_TERMCRIT_EPS + CV_TERMCRIT_ITER, 30, 0.1));
			drawChessboardCorners(view, boardSize, Mat(pointBuf), found);
			bitwise_not(view, view);
			imagePoints.push_back(pointBuf);
			cout << '.';
		}
		imshow("View", view);
		waitKey(50);
	}

	cout << "有效棋盘格张数" << nums << endl;

	//calculate chessboardCorners
	calcChessboardCorners(boardSize, squareSize, ObjectPoints[0]);
	ObjectPoints.resize(imagePoints.size(), ObjectPoints[0]);

	rms = calibrateCamera(ObjectPoints, imagePoints, imageSize, intrMat, distCoeffs,
		rvecs, tvecs);
	ok = checkRange(intrMat) && checkRange(distCoeffs);

	if (ok)
	{
		cout << "done with RMS error=" << rms << endl;
		return true;
	}
	else
		return false;
}

int main()
{
	//initialize some parameters
	bool okcalib = false;
	Mat intrMatFirst, intrMatSec, distCoeffsFirst, distCoffesSec;
	Mat R, T, E, F, RFirst, RSec, PFirst, PSec, Q;
	vector> imagePointsFirst, imagePointsSec;
	vector> ObjectPoints(1);
	Rect validRoi[2];
	Size imageSize;
	int cameraIdFirst = 0, cameraIdSec = 1;
	double rms = 0;

	//get pictures and calibrate
	vector imageList;
	string filename = "D:\\desktop\\双目\\学习例程\\TestOpencv\\x64\\Debug\\stereo_calibration.xml";
	bool okread = readStringList(filename, imageList);
	if (!okread || imageList.empty())
	{
		cout << "can not open " << filename << " or the string list is empty" << endl;
		return false;
	}
	if (imageList.size() % 2 != 0)
	{
		cout << "Error: the image list contains odd (non-even) number of elements\n";
		return false;
	}

	FileStorage fs("intrinsics.yml", FileStorage::WRITE);
	//calibrate

	cout << "calibrate left camera..." << endl;
	okcalib = calibrate(intrMatFirst, distCoeffsFirst, imagePointsFirst, ObjectPoints,
		imageSize, cameraIdFirst, imageList);

	if (!okcalib)
	{
		cout << "fail to calibrate left camera" << endl;
		return -1;
	}
	else
	{
		cout << "calibrate the right camera..." << endl;
	}


	okcalib = calibrate(intrMatSec, distCoffesSec, imagePointsSec, ObjectPoints,
		imageSize, cameraIdSec, imageList);

	fs << "M1" << intrMatFirst << "D1" << distCoeffsFirst <<
		"M2" << intrMatSec << "D2" << distCoffesSec;

	if (!okcalib)
	{
		cout << "fail to calibrate the right camera" << endl;
		return -1;
	}
	destroyAllWindows();

	//estimate position and orientation
	cout << "estimate position and orientation of the second camera" << endl
		<< "relative to the first camera..." << endl;
	cout << intrMatFirst;
	cout << distCoeffsFirst;
	cout << intrMatSec;
	cout << distCoffesSec;

	rms = stereoCalibrate(ObjectPoints, imagePointsFirst, imagePointsSec,
		intrMatFirst, distCoeffsFirst, intrMatSec, distCoffesSec,
		imageSize, R, T, E, F, CALIB_USE_INTRINSIC_GUESS,//CV_CALIB_FIX_INTRINSIC,
		TermCriteria(TermCriteria::COUNT + TermCriteria::EPS, 30, 1e-6));          //计算重投影误差
	cout << "done with RMS error=" << rms << endl;

	//stereo rectify
	cout << "stereo rectify..." << endl;
	stereoRectify(intrMatFirst, distCoeffsFirst, intrMatSec, distCoffesSec, imageSize, R, T, RFirst,
		RSec, PFirst, PSec, Q, CALIB_ZERO_DISPARITY, -1, imageSize, &validRoi[0], &validRoi[1]);
	cout << "Q" << Q << endl;
	cout << "P1" << PFirst << endl;
	cout << "P2" << PSec << endl;
	//read pictures for 3d-reconstruction

	if (fs.isOpened())
	{
		cout << "in";
		fs << "R" << R << "T" << T << "R1" << RFirst << "R2" << RSec << "P1" << PFirst << "P2" << PSec << "Q" << Q;
		fs.release();
	}

	namedWindow("canvas", 1);
	cout << "read the picture for 3d-reconstruction...";
	Mat canvas(imageSize.height, imageSize.width * 2, CV_8UC3), viewLeft, viewRight;
	Mat canLeft = canvas(Rect(0, 0, imageSize.width, imageSize.height));
	Mat canRight = canvas(Rect(imageSize.width, 0, imageSize.width, imageSize.height));

	viewLeft = imread(imageList[6], 1);//cameraIdFirst
	viewRight = imread(imageList[7], 1); //cameraIdSec
	viewLeft.copyTo(canLeft);
	viewRight.copyTo(canRight);
	cout << "done" << endl;
	imshow("canvas", canvas);
	waitKey(50); //必须要加waitKey ，否则可能存在无法显示图像问题


	//stereoRectify
	Mat rmapFirst[2], rmapSec[2], rviewFirst, rviewSec;
	initUndistortRectifyMap(intrMatFirst, distCoeffsFirst, RFirst, PFirst,
		imageSize, CV_16SC2, rmapFirst[0], rmapFirst[1]);//CV_16SC2
	initUndistortRectifyMap(intrMatSec, distCoffesSec, RSec, PSec,//CV_16SC2
		imageSize, CV_16SC2, rmapSec[0], rmapSec[1]);
	remap(viewLeft, rviewFirst, rmapFirst[0], rmapFirst[1], INTER_LINEAR);
	imshow("remap", rviewFirst);
	waitKey(40);

	remap(viewRight, rviewSec, rmapSec[0], rmapSec[1], INTER_LINEAR);
	rviewFirst.copyTo(canLeft);
	rviewSec.copyTo(canRight);

	//rectangle(canLeft, validRoi[0], Scalar(255, 0, 0), 3, 8);
	//rectangle(canRight, validRoi[1], Scalar(255, 0, 0), 3, 8);

	Mat before_rectify = imread("./picture/total_0.png");

	for (int j = 0; j <= canvas.rows; j += 16)  //画绿线
		line(canvas, Point(0, j), Point(canvas.cols, j), Scalar(0, 255, 0), 1, 8);

	for (int j = 0; j <= canvas.rows; j += 16)  //画绿线
		line(before_rectify, Point(0, j), Point(canvas.cols, j), Scalar(0, 255, 0), 1, 8);
	cout << "stereo rectify done" << endl;

	imshow("校正前", before_rectify); //显示画绿线的校正后图像
	imshow("校正后", canvas); //显示画绿线的校正前图像

	waitKey(400000);//必须要加waitKey ，否则可能存在无法显示图像问题



	return 0;
}

三、标定板