c++ opencv读/写yaml文件(相机参数，外参矩阵等)

参考博文："OpenCV —数据持久化: FileStorage类的数据存取操作与示例"
https://blog.****.net/iracer/article/details/51339377

注意：使用FileStorage的前提是yaml文件必须遵循以下格式：
%YAML:1.0
fx: 100.
fy: 101.

否则无法使用，会提示找不到输入文件

使用FileStorage读取yaml存储的外参矩阵：

写入操作：

cv::FileStorage fs("test.yml", FileStorage::WRITE);
int imageWidth= 5;
int imageHeight= 10;
fs << "imageWidth" << imageWidth;
fs << "imageHeight" << imageHeight;
 
cv::Mat m1= Mat::eye(3,3, CV_8U);
cv::Mat m2= Mat::ones(3,3, CV_8U);
cv::Mat resultMat= (m1+1).mul(m1+2);
fs << "resultMat" << resultMat;
 
cv::Mat cameraMatrix = (Mat_<double>(3,3) << 1000, 0, 320, 0, 1000, 240, 0, 0, 1);
cv::Mat distCoeffs = (Mat_<double>(5,1) << 0.1, 0.01, -0.001, 0, 0);
fs << "cameraMatrix" << cameraMatrix << "distCoeffs" << distCoeffs;

time_t rawtime; time(&rawtime); //#include <time.h>
fs << "calibrationDate" << asctime(localtime(&rawtime));
 
fs.release();    	//close the file opened

打开文件的两种方式：
1. 
cv::FileStorage fs;
fs.open("test.yml",FileStorage::WRITE);
......
fs.release()

2.
cv::FileStorage fs("test.yml", FileStorage::WRITE);

读取操作
 

// read data using operator []
	cv::FileStorage fs("test.yml", FileStorage::READ);
	int width;
	int height;
	fs["imageWidth"]>>width;
	fs["imageHeight"]>>height;
	cout<<"width readed = "<<width<<endl;
	cout<<"height readed = "<<height<<endl<<endl;
 
// read Mat
	cv::Mat resultMatRead;
	fs["resultMat"]>>resultMatRead;
	cout<<"resultMat readed = "<<resultMatRead<<endl<<endl;
	
	cv::Mat cameraMatrixRead,distCoeffsRead;
	fs["cameraMatrix"]>>cameraMatrixRead;
	fs["distCoeffs"]>>distCoeffsRead;
	cout<<"cameraMatrix readed = "<<cameraMatrixRead<<endl;
	cout<<"distCoeffs readed = "<<distCoeffsRead<<endl<<endl;
 
// read string
	string timeRead;
	fs["calibrationDate"]>>timeRead;
	cout<<"calibrationDate readed = "<<timeRead<<endl<<endl;
 
	fs.release();