Question

我正在尝试为interp2寻找一个等效的OpenCV函数，我参考这个海报在OpenCV中使用重映射功能。

cv::remap (in opencv) and interp2 (matlab)

但是，我意识到这两个功能之间的输出存在显着差异。这是我的Matlab代码

U = [0.1 0.1 0.1; 0.2 0.2 0.2; 0.3 0.3 0.3];
X = [0 0 0; 0.5 0.5 0.5; 1 1 1];
Y = [0 0.5 1;0 0.5 1;0 0.5 1];
V = interp2(U,X,Y,'linear',NaN)

我得到输出V矩阵为

   NaN       NaN       NaN
   NaN       NaN       NaN
   NaN       NaN    0.1000

这是我的OpenCV代码

#include "highgui.h"
#include "cv.h"
using namespace cv;
using namespace std;

int main(int argc, char** argv)
{
    //generate flowmap model
    CvFileStorage* fx = cvOpenFileStorage("result.txt", 0, CV_STORAGE_WRITE);//ask storage for save file
    Mat xmesh = cvCreateMat(3, 3, 5);
    Mat ymesh = cvCreateMat(3, 3, 5);

    for (int i = 0; i < xmesh.rows; i++)
        for (int j = 0; j < xmesh.cols; j++)
        {
            xmesh.at<float>(i, j) = i*0.5;
            ymesh.at<float>(i, j) = j*0.5;
        }

    //generate optical flow folder
    Mat u = cvCreateMat(3, 3, 5);

    for (int i = 0; i <u.rows; i++)
        for (int j = 0; j < u.cols; j++)
        {
            u.at<float>(i, j) = (i + 1)*0.1;
        }
    Mat v = Mat::zeros(u.size(), u.type());

    remap(u, v, xmesh, ymesh, INTER_LINEAR, 0, cvScalarAll(0));

    //convert mat to Iplimage
    IplImage* xmesh_a = cvCloneImage(&(IplImage)xmesh);
    IplImage* ymesh_a = cvCloneImage(&(IplImage)ymesh);
    IplImage* u_a = cvCloneImage(&(IplImage)u);
    IplImage* v_a = cvCloneImage(&(IplImage)v);

    //save end to txt
    cvWrite(fx, "xmesh", xmesh_a, cvAttrList());
    cvWrite(fx, "ymesh", ymesh_a, cvAttrList());
    cvWrite(fx, "u", u_a, cvAttrList());
    cvWrite(fx, "v", v_a, cvAttrList());
    cvReleaseFileStorage(&fx);

    waitKey();

}

我得到的输出V矩阵是

1.00000001e-001, 1.50000006e-001, 2.00000003e-001,
1.00000001e-001, 1.50000006e-001, 2.00000003e-001,
1.00000001e-001, 1.50000006e-001, 2.00000003e-001

任何帮助将不胜感激。谢谢！

Answer 1

结果的差异与c ++和MATLAB之间的索引差异有关，分别是0和1。

interp2(U,X,Y,'linear',NaN)与interp2(1:3,1:3,U,X,Y,'linear',NaN)相同，将其更改为interp2(0:2,0:2,U,X,Y,'linear',NaN)，您将获得与OpenCV相同的结果。

如果您希望remap的结果与interp2的结果相同，您可以将xmesh和ymesh向后移一步并搜索产生的负位置nan值。

#include <cmath>
//...
//...
for (int i = 0; i < xmesh.rows; i++)
    for (int j = 0; j < xmesh.cols; j++)
    {
        xmesh.at<float>(i, j) = i*0.5-1;
        ymesh.at<float>(i, j) = j*0.5-1;
    }
//...
//...
remap(u, v, xmesh, ymesh, INTER_LINEAR, 0, cvScalarAll(NAN));

结果：

nan nan nan 
nan nan nan
nan nan 0.1

与OpenCV Remap相比，Matlab Interp2的功能行为有所不同

1 个答案: