gcc链接错误：未定义对符号'_ZN2cv5flann12SearchParamsC1Eifb'的引用，[重复]

Posted 2023-02-22

【中文标题】gcc链接错误：未定义对符号\'_ZN2cv5flann12SearchParamsC1Eifb\'的引用，[重复]

【英文标题】：gcc linking error: undefined reference to symbol '_ZN2cv5flann12SearchParamsC1Eifb', [duplicate]gcc链接错误：未定义对符号'_ZN2cv5flann12SearchParamsC1Eifb'的引用，[重复]

【发布时间】：2016-01-04 14:46:11

【问题描述】：

我正在使用OpenCv 和 Eclipse 来实现单应性匹配。构建时出现以下错误：

/usr/bin/ld: ./src/flann.o: 未定义的符号引用 '_ZN2cv5flann12SearchParamsC1Eifb'

An image of compilation error.

这是我的代码：

#include <stdio.h>
#include <iostream>
#include "opencv2/core/core.hpp"
#include "opencv2/features2d/features2d.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/calib3d/calib3d.hpp"
#include "opencv2/nonfree/nonfree.hpp"

using namespace cv;

void readme();

/** @function main */
int main()



  Mat img_object = imread( "/home/gaps/Desktop/DSC00268.JPG");
  Mat img_scene = imread( "/home/gaps/Desktop/chart_1-2_1816185b.jpg" );

  if( !img_object.data || !img_scene.data )
   
std::cout<< " --(!) Error reading images " << std::endl; return -1; 


  //-- Step 1: Detect the keypoints using SURF Detector
  int minHessian = 400;

  SurfFeatureDetector detector( minHessian );

  std::vector<KeyPoint> keypoints_object, keypoints_scene;

  detector.detect( img_object, keypoints_object );
  detector.detect( img_scene, keypoints_scene );

  //-- Step 2: Calculate descriptors (feature vectors)
  SurfDescriptorExtractor extractor;

  Mat descriptors_object, descriptors_scene;

  extractor.compute( img_object, keypoints_object, descriptors_object );
  extractor.compute( img_scene, keypoints_scene, descriptors_scene );

  //-- Step 3: Matching descriptor vectors using FLANN matcher
  FlannBasedMatcher matcher;
  std::vector< DMatch > matches;
  matcher.match( descriptors_object, descriptors_scene, matches );

  double max_dist = 0; double min_dist = 100;

  //-- Quick calculation of max and min distances between keypoints
  for( int i = 0; i < descriptors_object.rows; i++ )
   double dist = matches[i].distance;
    if( dist < min_dist ) min_dist = dist;
    if( dist > max_dist ) max_dist = dist;
  

  printf("-- Max dist : %f \n", max_dist );
  printf("-- Min dist : %f \n", min_dist );

  //-- Draw only "good" matches (i.e. whose distance is less than 3*min_dist )
  std::vector< DMatch > good_matches;

  for( int i = 0; i < descriptors_object.rows; i++ )
   if( matches[i].distance < 3*min_dist )
      good_matches.push_back( matches[i]); 
  

  Mat img_matches;
  drawMatches( img_object, keypoints_object, img_scene, keypoints_scene,
               good_matches, img_matches, Scalar::all(-1), Scalar::all(-1),
               vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );

  //-- Localize the object
  std::vector<Point2f> obj;
  std::vector<Point2f> scene;

  for( int i = 0; i < good_matches.size(); i++ )
  
    //-- Get the keypoints from the good matches
    obj.push_back( keypoints_object[ good_matches[i].queryIdx ].pt );
    scene.push_back( keypoints_scene[ good_matches[i].trainIdx ].pt );
  

  Mat H = findHomography( obj, scene, CV_RANSAC );

  //-- Get the corners from the image_1 ( the object to be "detected" )
  std::vector<Point2f> obj_corners(4);
  obj_corners[0] = cvPoint(0,0); obj_corners[1] = cvPoint( img_object.cols, 0 );
  obj_corners[2] = cvPoint( img_object.cols, img_object.rows ); obj_corners[3] = cvPoint( 0, img_object.rows );
  std::vector<Point2f> scene_corners(4);

  perspectiveTransform( obj_corners, scene_corners, H);

  //-- Draw lines between the corners (the mapped object in the scene - image_2 )
  line( img_matches, scene_corners[0] + Point2f( img_object.cols, 0), scene_corners[1] + Point2f( img_object.cols, 0), Scalar(0, 255, 0), 4 );
  line( img_matches, scene_corners[1] + Point2f( img_object.cols, 0), scene_corners[2] + Point2f( img_object.cols, 0), Scalar( 0, 255, 0), 4 );
  line( img_matches, scene_corners[2] + Point2f( img_object.cols, 0), scene_corners[3] + Point2f( img_object.cols, 0), Scalar( 0, 255, 0), 4 );
  line( img_matches, scene_corners[3] + Point2f( img_object.cols, 0), scene_corners[0] + Point2f( img_object.cols, 0), Scalar( 0, 255, 0), 4 );

  //-- Show detected matches
  imshow( "Good Matches & Object detection", img_matches );

  waitKey(0);
  return 0;
  

  /** @function readme */
  void readme()
   
std::cout << " Usage: ./SURF_descriptor <img1> <img2>" << std::endl; 

【问题讨论】：

但我无法找到解决方案，上述问题的所有答案都指定了问题，但任何特定的解决方案@AndyG

OpenCV 可能未正确安装，或者在您的路径中未正确引用（编译器找不到合适的文件）。尝试编写一个更简单的程序来重新创建问题，然后专注于解决那些链接器错误。

所有其他程序和项目都运行良好，除了这个

也许你的make文件有误？尝试执行完全清理（删除所有中间文件）并重建。

做了，还是不行

【参考方案1】：

您没有链接libopencv_flann，其中定义了未定义的符号。将-lopencv_flann 添加到您的链接器选项中。