c++ LK光流的使用代码

以下是使用C++实现LK光流的示例代码：

#include <opencv2/opencv.hpp>

using namespace cv;

int main()
{
    // 读取两张图像
    Mat prev_frame = imread("prev_frame.jpg", IMREAD_GRAYSCALE);
    Mat next_frame = imread("next_frame.jpg", IMREAD_GRAYSCALE);

    // 设置LK光流参数
    TermCriteria criteria = TermCriteria(TermCriteria::COUNT + TermCriteria::EPS, 10, 0.03);
    Size winSize = Size(15, 15);
    int maxLevel = 2;
    double minEigThreshold = 0.01;

    // 找到关键点
    std::vector<Point2f> prev_corners, next_corners;
    goodFeaturesToTrack(prev_frame, prev_corners, 200, 0.01, 10);
    calcOpticalFlowPyrLK(prev_frame, next_frame, prev_corners, next_corners, status, error, winSize, maxLevel, criteria, 0, minEigThreshold);

    // 筛选出好的关键点
    std::vector<Point2f> good_prev_corners, good_next_corners;
    for (int i = 0; i < prev_corners.size(); i++)
    {
        if (status[i] == 1)  // 说明找到了对应的点
        {
            good_prev_corners.push_back(prev_corners[i]);
            good_next_corners.push_back(next_corners[i]);
        }
    }

    // 画出关键点和运动轨迹
    Mat frame = imread("prev_frame.jpg");
    Mat mask = Mat::zeros(frame.size(), frame.type());
    for (int i = 0; i < good_prev_corners.size(); i++)
    {
        Point2f prev_pt = good_prev_corners[i];
        Point2f next_pt = good_next_corners[i];
        line(mask, next_pt, prev_pt, Scalar(0, 255, 0), 2);
        circle(frame, next_pt, 5, Scalar(0, 0, 255), -1);
    }

    // 显示图像
    imshow("frame", frame);
    imshow("mask", mask);
    waitKey(0);
    destroyAllWindows();

    return 0;
}

需要注意的是，C++中的LK光流函数与Python中的函数名略有不同，例如`cv::goodFeaturesToTrack()`、`cv::calcOpticalFlowPyrLK()`等。另外，C++中需要手动筛选出好的关键点，方法是通过`status`数组筛选出对应的点，将其存放到另一个向量中即可。