最近利用VS2013+OpevCV3.4.1演示如何使用2D-2D的特征匹配估计相机运动过程中出错,如图:
经调试,发现代码在执行find_feature_matches()函数的最后一行代码,然后返回时报了上述错误。初步看来是内存泄漏的问题,多次检查无果后,换了个思路。因为之前吃过环境变量设置的亏,然后又检查了一下OpenCV3.4.1环境变量设置,仍然没有问题。直到我看到这篇文章才突然想到会不会是因为VS2013和OpenCV3.4.1的版本不匹配的缘故。如图:
最后我直接改用VS2015来跑改程序,就没有再出现这个问题了。
具体程序如下:
#include
#include
#include
#include
#include
#include
// #include "extra.h" // use this if in OpenCV2
using namespace std;
using namespace cv;
/****************************************************
* 本程序演示了如何使用2D-2D的特征匹配估计相机运动
* **************************************************/
void find_feature_matches(
const Mat &img_1, const Mat &img_2,
std::vector &keypoints_1,
std::vector &keypoints_2,
std::vector &matches);
void pose_estimation_2d2d(
std::vector keypoints_1,
std::vector keypoints_2,
std::vector matches,
Mat &R, Mat &t);
// 像素坐标转相机归一化坐标
Point2d pixel2cam(const Point2d &p, const Mat &K);
int main(int argc, char **argv) {
if (argc != 3) {
cout << "usage: pose_estimation_2d2d img1 img2" << endl;
return 1;
}
//-- 读取图像
Mat img_1 = imread(argv[1], CV_LOAD_IMAGE_COLOR);
Mat img_2 = imread(argv[2], CV_LOAD_IMAGE_COLOR);
assert(img_1.data && img_2.data && "Can not load images!");
// imshow("原图1", img_1);//wxh
vector keypoints_1, keypoints_2;
vector matches;
find_feature_matches(img_1, img_2, keypoints_1, keypoints_2, matches);
cout << "一共找到了" << matches.size() << "组匹配点" << endl;
//-- 估计两张图像间运动
Mat R, t;
pose_estimation_2d2d(keypoints_1, keypoints_2, matches, R, t);
//-- 验证E=t^R*scale
Mat t_x =
(Mat_(3, 3) << 0, -t.at(2, 0), t.at(1, 0),
t.at(2, 0), 0, -t.at(0, 0),
-t.at(1, 0), t.at(0, 0), 0);
cout << "t^R=" << endl << t_x * R << endl;
//-- 验证对极约束
/*Mat K = (Mat_(3, 3) << 520.9, 0, 325.1, 0, 521.0, 249.7, 0, 0, 1);*/
Mat K = (Mat_(3, 3) << 517.306408, 0, 318.643040, 0, 516.469215, 255.313989, 0, 0, 1);
for (DMatch m : matches) {
Point2d pt1 = pixel2cam(keypoints_1[m.queryIdx].pt, K);
Mat y1 = (Mat_(3, 1) << pt1.x, pt1.y, 1);
Point2d pt2 = pixel2cam(keypoints_2[m.trainIdx].pt, K);
Mat y2 = (Mat_(3, 1) << pt2.x, pt2.y, 1);
Mat d = y2.t() * t_x * R * y1;
cout << "epipolar constraint = " << d << endl;
}
return 0;
}
void find_feature_matches(const Mat &img_1, const Mat &img_2,
std::vector &keypoints_1,
std::vector &keypoints_2,
std::vector &matches)
{
//-- 初始化
Mat descriptors_1, descriptors_2;
// used in OpenCV3
Ptr detector = ORB::create();
Ptr descriptor = ORB::create();
// use this if you are in OpenCV2
// Ptr detector = FeatureDetector::create ( "ORB" );
// Ptr descriptor = DescriptorExtractor::create ( "ORB" );
Ptr matcher = DescriptorMatcher::create("BruteForce-Hamming");
//-- 第一步:检测 Oriented FAST 角点位置
detector->detect(img_1, keypoints_1);
detector->detect(img_2, keypoints_2);
//-- 第二步:根据角点位置计算 BRIEF 描述子
descriptor->compute(img_1, keypoints_1, descriptors_1);
descriptor->compute(img_2, keypoints_2, descriptors_2);
//-- 第三步:对两幅图像中的BRIEF描述子进行匹配,使用 Hamming 距离
vector match;
//BFMatcher matcher ( NORM_HAMMING );
matcher->match(descriptors_1, descriptors_2, match);
//-- 第四步:匹配点对筛选
double min_dist = 10000, max_dist = 0;
//找出所有匹配之间的最小距离和最大距离, 即是最相似的和最不相似的两组点之间的距离
for (int i = 0; i < descriptors_1.rows; i++) {
double dist = match[i].distance;
printf("match[i].distance:%f\n", match[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);
//当描述子之间的距离大于两倍的最小距离时,即认为匹配有误.但有时候最小距离会非常小,设置一个经验值30作为下限.
for (int i = 0; i < descriptors_1.rows; i++) {
if (match[i].distance <= max(2 * min_dist, 30.0)) {
matches.push_back(match[i]);
}
}
}
Point2d pixel2cam(const Point2d &p, const Mat &K) {
return Point2d
(
(p.x - K.at(0, 2)) / K.at(0, 0),
(p.y - K.at(1, 2)) / K.at(1, 1)
);
}
void pose_estimation_2d2d(std::vector keypoints_1,
std::vector keypoints_2,
std::vector matches,
Mat &R, Mat &t) {
// 相机内参,TUM Freiburg2
Mat K = (Mat_(3, 3) << 517.306408, 0, 318.643040, 0, 516.469215, 255.313989, 0, 0, 1/*520.9, 0, 325.1, 0, 521.0, 249.7, 0, 0, 1*/);
//-- 把匹配点转换为vector的形式
vector points1;
vector points2;
for (int i = 0; i < (int)matches.size(); i++) {
points1.push_back(keypoints_1[matches[i].queryIdx].pt);
points2.push_back(keypoints_2[matches[i].trainIdx].pt);
}
//-- 计算基础矩阵
Mat fundamental_matrix;
fundamental_matrix = findFundamentalMat(points1, points2, CV_FM_8POINT);
cout << "fundamental_matrix is " << endl << fundamental_matrix << endl;
//-- 计算本质矩阵
Point2d principal_point(/*325.1, 249.7*/318.643040, 255.313989); //相机光心, TUM dataset标定值
double focal_length = 521; //相机焦距, TUM dataset标定值
Mat essential_matrix;
essential_matrix = findEssentialMat(points1, points2, focal_length, principal_point);
cout << "essential_matrix is " << endl << essential_matrix << endl;
//-- 计算单应矩阵
//-- 但是本例中场景不是平面,单应矩阵意义不大
Mat homography_matrix;
homography_matrix = findHomography(points1, points2, RANSAC, 3);
cout << "homography_matrix is " << endl << homography_matrix << endl;
//-- 从本质矩阵中恢复旋转和平移信息.
// 此函数仅在Opencv3中提供
recoverPose(essential_matrix, points1, points2, R, t, focal_length, principal_point);
cout << "R is " << endl << R << endl;
cout << "t is " << endl << t << endl;
}