Question

在openCV中，我已经在我的应用程序中修改了这个教程代码

http://docs.opencv.org/2.4.2/doc/tutorials/features2d/feature_homography/feature_homography.html#feature-homography

我一直试图使用最近邻距离比率修剪匹配，只能绘制超过某个阈值的匹配。

  double ratio = 0.9;
  std::vector< vector<DMatch > > nnMatches;
  std::vector< DMatch > good_NNmatches;
  matcher.knnMatch(descriptors_scene, descriptors_object, nnMatches, 2 );

  for(int k = 0; k < nnMatches.size(); k++)
  {
      if(nnMatches[k][0].distance / nnMatches[k][1].distance > ratio)
      {
          good_NNmatches.push_back(nnMatches[k][0]);
      }
  }

然后我尝试使用教程中演示的相同方法在good_NNmatches中绘制匹配但是我收到以下错误：

OpenCV Error: Assertion failed (i1 >= 0 && i1 < static_cast<int>(keypoints1.size())) in     drawMatches, file /Users/cgray/Downloads/opencv-2.4.6/modules/features2d/src/draw.cpp, line 207
libc++abi.dylib: terminating with uncaught exception of type cv::Exception: /Users/cgray/Downloads/opencv-2.4.6/modules/features2d/src/draw.cpp:207: error: (-215) i1 >= 0 && i1 < static_cast<int>(keypoints1.size()) in function drawMatches

当尝试使用good_nnMatches而不是good_matches调用drawMatches时，如教程中所述。

drawMatches( roiImg, keypoints_object, compare, keypoints_scene,
                     good_NNmatches, img_matches, Scalar::all(-1), Scalar::all(-1),
                     vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );

Answer 1

我遇到了同样的问题。就我而言，我正在做

cv::Mat output;
drawMatches( smallimg, keyptsSm, bigimg, keyptsBg, matchesBig2Small, output );

匹配matchesBig2Small的计算位置从bigimg到smallimg

std::vector<cv::DMatch> matchesBig2Small; 
//match from bigimg to smallimg

所以你得到的错误实际上是说它正在寻找smallimg中实际引用第二个图像的关键点索引，这个图像更大，所以你超过了smallimg的大小。因此，要么将对drawMatches的调用更改为：

drawMatches( bigimg, keyptsBg, smallimg, keyptsSm, matchesBig2Small, output );

或者将您计算匹配的方式更改为smallimg到bigimg，因此您需要matchesBig2Small代替matchesSmall2Big，然后才能调用将是：

std::vector<cv::DMatch> matchesSmall2Big; 
//match from smallimg to bigimg
drawMatches( smallimg, keyptsSm, bigimg, keyptsBg, matchesSmall2Big, output );

Answer 2

在经过一些试验和错误后，我似乎已经解决了这个问题。

我更改了drawMatches方法，将“roiImg”和关键点与“compare”和关键点交换。

drawMatches(compare, keypoints_scene, roiImg, keypoints_object,
               good_NNmatches, img_matches, Scalar::all(-1), Scalar::all(-1),
               vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );

这停止了断言错误。但是由于在检索关键点时交换了值，我还必须进行一些更改。 trainIdx和queryIdx也已被交换以考虑先前所做的更改。

obj.push_back( keypoints_object[ good_NNmatches[i].trainIdx ].pt );
scene.push_back( keypoints_scene[ good_NNmatches[i].queryIdx ].pt );

Answer 3

我做到了，我没有任何问题我希望这段代码可以帮到你

double NNDR;

    for(int i=0;i<(int)ORB_ORB_matches.size(); i++){

        NNDR= ( ORB_ORB_matches[i][0].distance/ORB_ORB_matches[i][1].distance );

        if(NNDR <= 0.9){

            ORB_single_matches.push_back (ORB_ORB_matches[i][0]);

        }

    }
drawMatches( image_1, keypoints_1, image_2, keypoints_2, ORB_single_matches, img_matches,Scalar::all(-1),Scalar::all(-1),vector<char>(),`enter code here`          DrawMatchesFlags::DRAW_RICH_KEYPOINTS|DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS);

从最近邻距离比绘制匹配

3 个答案: