使用Opencv 写入、读取Yaml文件

在我们的工程中，经常需要读取相关的配置参数，个人比较喜欢使用Yaml文件来配置。下面介绍使用opencv轻松写入、读取Yaml文件的方法。

1.写入文件例子：

#include <opencv2/opencv.hpp>
#include <time.h>
#include <iostream>

int main(int argc, char** argv)
{
  //write a yaml file
  cv::FileStorage fs_write("./test.yaml", cv::FileStorage::WRITE);

  time_t rawtime;
  time(&rawtime);
  fs_write << "Time" << asctime(localtime(&rawtime));
  
  std::vector<int> image_size = {1280, 800};
  fs_write << "imageSize" << image_size; 

  cv::Mat camera_matrix = (cv::Mat_<double>(3, 3) << 190, 0, 640, 
                                                     0, 190, 400, 
                                                     0, 0, 1);
  cv::Mat distort_coefficient = (cv::Mat_<double>(5, 1) << 0.1, 0.01, -0.001, 0, 0);
  fs_write << "cameraMatrix" << camera_matrix << "distCoeffs" << distort_coefficient;
    
  fs_write.release();

  return 0;
}

说明：

1. 使用cv::FileStorage创建文件对象，打开文件
2. 使用<<往文件中写入信息
3. release()关闭文件

输出文件结果：

%YAML:1.0
---
Time: "Thu Nov 28 14:02:31 2019\n"
imageSize: [ 1280, 800 ]
cameraMatrix: !!opencv-matrix
   rows: 3
   cols: 3
   dt: d
   data: [ 190., 0., 640., 0., 190., 400., 0., 0., 1. ]
distCoeffs: !!opencv-matrix
   rows: 5
   cols: 1
   dt: d
   data: [ 1.0000000000000001e-01, 1.0000000000000000e-02,
       -1.0000000000000000e-03, 0., 0. ]

2.读取文件例子：

#include <opencv2/opencv.hpp>
#include <iostream>
#include <vector>

int main(int argc, char **argv)
{
    //read a yaml file
    cv::FileStorage fs_read("./test.yaml", cv::FileStorage::READ);

    std::string time;
    //second method:use FileNode::operator >>
    fs_read["Time"] >> time;

    std::vector<int> image_size;
    fs_read["imageSize"] >> image_size;

    cv::Mat camera_matrix, distort_coefficient;
    fs_read["cameraMatrix"] >> camera_matrix;
    fs_read["distCoeffs"] >> distort_coefficient;

    std::cout << "Time: " << time << std::endl
              << "cameraMatrix: " << camera_matrix << std::endl
              << "distCoeffs: " << distort_coefficient << std::endl;

    fs_read.release();

    return 0;
}