Matlab Interp2的功能行为与OpenCV相比有所不同

Question

我正在尝试为interp2寻找一个等效的OpenCV函数，我参考这张海报以在OpenCV中使用重映射函数。

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

然而，我意识到，在这两个功能之间的输出的显著差异。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) 

我得到的输出V矩阵

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(); 

} 

的输出V矩阵我得到的是

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，它们分别是基于0和基于1的索引。

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

如果你想的remap结果是一样的，即interp2您可以在xmesh和ymesh一步移回并搜索负位置产生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