samples/cpp/polar_transforms.cpp

一个使用 cv::linearPolar 和 cv::logPolar 操作的示例

#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/videoio.hpp"
#include <iostream>
 
using namespace cv;
 
int main( int argc, char** argv )
{
    VideoCapture capture;
    Mat log_polar_img, lin_polar_img, recovered_log_polar, recovered_lin_polar_img;
 
    CommandLineParser parser(argc, argv, "{@input|0| 摄像头设备号或视频文件路径}");
parser.about("\n这个程序演示了线性极坐标和对数极坐标图像变换的用法\n");
parser.printMessage();
std::string arg = parser.get<std::string>("@input");
 
    if( arg.size() == 1 && isdigit(arg[0]) )
capture.open( arg[0] - '0' );
    else
capture.open(samples::findFileOrKeep(arg));
 
    if( !capture.isOpened() )
    {
fprintf(stderr,"无法初始化捕获...\n");
        return -1;
    }
 
namedWindow( "线性极坐标", WINDOW_AUTOSIZE );
namedWindow( "对数极坐标", WINDOW_AUTOSIZE);
namedWindow( "恢复的线性极坐标", WINDOW_AUTOSIZE);
namedWindow( "恢复的对数极坐标", WINDOW_AUTOSIZE);
 
moveWindow( "线性极坐标", 20,20 );
moveWindow( "对数极坐标", 700,20 );
moveWindow( "恢复的线性极坐标", 20, 350 );
moveWindow( "恢复的对数极坐标", 700, 350 );
    int flags = INTER_LINEAR + WARP_FILL_OUTLIERS;
    Mat src;
    for(;;)
    {
capture >> src;
 
        if(src.empty() )
            break;
 
        Point2f center( (float)src.cols / 2, (float)src.rows / 2 );
        double maxRadius = 0.7*min(center.y, center.x);
 
#if 0 // 已弃用
        double M = frame.cols / log(maxRadius);
logPolar(frame, log_polar_img, center, M, flags);
linearPolar(frame, lin_polar_img, center, maxRadius, flags);
 
logPolar(log_polar_img, recovered_log_polar, center, M, flags + WARP_INVERSE_MAP);
linearPolar(lin_polar_img, recovered_lin_polar_img, center, maxRadius, flags + WARP_INVERSE_MAP);
#endif
        // 直接变换
warpPolar(src, lin_polar_img, Size(),center, maxRadius, flags); // 线性极坐标
warpPolar(src, log_polar_img, Size(),center, maxRadius, flags + WARP_POLAR_LOG); // 半对数极坐标
        // 反变换
warpPolar(lin_polar_img, recovered_lin_polar_img, src.size(), center, maxRadius, flags + WARP_INVERSE_MAP);
warpPolar(log_polar_img, recovered_log_polar, src.size(), center, maxRadius, flags + WARP_POLAR_LOG + WARP_INVERSE_MAP);
 
        // 以下是 (rho, phi) -> (x, y) 的反变换
        Mat dst;
        if (flags & WARP_POLAR_LOG)
dst = log_polar_img;
        else
dst = lin_polar_img;
        // 从极坐标图像中获取一个点
        int rho = cvRound(dst.cols * 0.75);
        int phi = cvRound(dst.rows / 2.0);
 
        double angleRad, magnitude;
        double Kangle = dst.rows / CV_2PI;
angleRad = phi / Kangle;
        if (flags & WARP_POLAR_LOG)
        {
            double Klog = dst.cols / std::log(maxRadius);
magnitude = std::exp(rho / Klog);
        }
        else
        {
            double Klin = dst.cols / maxRadius;
magnitude = rho / Klin;
        }
        int x = cvRound(center.x + magnitude * cos(angleRad));
        int y = cvRound(center.y + magnitude * sin(angleRad));
drawMarker(src, Point(x, y), Scalar(0, 255, 0));
drawMarker(dst, Point(rho, phi), Scalar(0, 255, 0));
 
imshow("源帧", src);
imshow("对数极坐标", log_polar_img);
imshow("线性极坐标", lin_polar_img);
imshow("恢复的线性极坐标", recovered_lin_polar_img );
imshow("恢复的对数极坐标", recovered_log_polar );
 
        if( waitKey(10) >= 0 )
            break;
    }
    return 0;
}