Good day.
They gave the task: to find the angle of inclination of the object (in my case, the blades of the helicopter) and output all the video stream. Use VS2015 and OpenCV 2.4.13 Found an example on this site: Algorithm for determining the angle of rotation of the image . It helped a lot but there were some problems and some I decided, some didn't:
In the beginning she complained about the string
pts_mat.at<double>(j,0) = pts[j].x; solved the problem by changing the variable pts [j] .x to contoue [j] .x and y, respectively. Later I solved the necessary libraries.
#include <iostream> #include <opencv2/opencv.hpp> #include <opencv2/highgui/highgui.hpp> using namespace std; using namespace cv; double angle; int main(); { Mat src_mat = imread("E:/work/project/opencv/Find_object/Find_object/blade2.jpg", CV_LOAD_IMAGE_COLOR); imshow("blade", src_mat); if (src_mat.empty() == NULL) { cout << "File not find!"; } Mat gry_mat; cvtColor(src_mat, gry_mat, COLOR_BGR2GRAY); threshold(gry_mat, gry_mat, 150, 255, CV_THRESH_BINARY); vector<vector<Point> > contours; vector<Vec4i> hierarchy; findContours(gry_mat, contours, hierarchy, CV_RETR_LIST, CV_CHAIN_APPROX_NONE); int sz = static_cast<int>(contours.size()); for (int i = 0, n = contours.size(); i < n; ++i) { const vector<Point> &contour = contours.at(i); // Отсеиваем слишком маленькие, либо слишком большие. double area = contourArea(contour); if (area < 1e2 || 1e5 < area) continue; // Строим буфер для PCA. int sz = static_cast<int>(contour.size()); Mat pts_mat = Mat (sz, 2, CV_64FC1); for (int j = 0; j < pts_mat.rows; ++j) { pts_mat.at<double>(j, 0) = contour[j].x; pts_mat.at<double>(j, 1) = contour[j].y; } PCA pca(pts_mat, Mat(), CV_PCA_DATA_AS_ROW); // В отдельный вектор выносим собственные вектора, // полученные при помощи PCA. vector<Point2d> eigen_vecs(2); for (int j = 0; j < 2; ++j) { eigen_vecs[j] = Point2d(pca.eigenvectors.at<double>(j, 0), pca.eigenvectors.at<double>(j, 1)); } // Искомый угол. angle = atan2(eigen_vecs[0].y, eigen_vecs[0].x); cout << "Angin[" << i << "] =" << angle << "\n"; } return angle; } everything works, calculates, but an error is displayed 
comes out after the work of the entire program. Help me please.
Required dlls: core, highgui, imgproc;
