OpenCV 3 中的 PCA 错误
Error with PCA in OpenCV 3
我正在尝试从此链接运行OpenCV for PCA的示例代码PCA 示例。
但是在我运行后它崩溃了。我调试了,我看到它在下面的for loop
里面崩溃了,这是getOrientation
函数:
for (int i = 0; i < 2; ++i)
{
eigen_vecs[i] = Point2d(pca_analysis.eigenvectors.at<double>(i, 0),
pca_analysis.eigenvectors.at<double>(i, 1));
eigen_val[i] = pca_analysis.eigenvalues.at<double>(0, i);
}
我之前在stackoverflow中搜索过,有一些标题相似但错误不同的问题。有什么帮助吗?谢谢
下面是示例代码:
#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
// Function declarations
void drawAxis(Mat&, Point, Point, Scalar, const float);
double getOrientation(const vector<Point> &, Mat&);
void drawAxis(Mat& img, Point p, Point q, Scalar colour, const float scale = 0.2)
{
double angle;
double hypotenuse;
angle = atan2((double)p.y - q.y, (double)p.x - q.x); // angle in radians
hypotenuse = sqrt((double)(p.y - q.y) * (p.y - q.y) + (p.x - q.x) * (p.x - q.x));
// double degrees = angle * 180 / CV_PI; // convert radians to degrees (0-180 range)
// cout << "Degrees: " << abs(degrees - 180) << endl; // angle in 0-360 degrees range
// Here we lengthen the arrow by a factor of scale
q.x = (int)(p.x - scale * hypotenuse * cos(angle));
q.y = (int)(p.y - scale * hypotenuse * sin(angle));
line(img, p, q, colour, 1, CV_AA);
// create the arrow hooks
p.x = (int)(q.x + 9 * cos(angle + CV_PI / 4));
p.y = (int)(q.y + 9 * sin(angle + CV_PI / 4));
line(img, p, q, colour, 1, CV_AA);
p.x = (int)(q.x + 9 * cos(angle - CV_PI / 4));
p.y = (int)(q.y + 9 * sin(angle - CV_PI / 4));
line(img, p, q, colour, 1, CV_AA);
}
double getOrientation(const vector<Point> &pts, Mat &img)
{
//Construct a buffer used by the pca analysis
int sz = static_cast<int>(pts.size());
Mat data_pts = Mat(sz, 2, CV_64FC1);
for (int i = 0; i < data_pts.rows; ++i)
{
data_pts.at<double>(i, 0) = pts[i].x;
data_pts.at<double>(i, 1) = pts[i].y;
}
//Perform PCA analysis
PCA pca_analysis(data_pts, Mat(), CV_PCA_DATA_AS_ROW);
//Store the center of the object
Point cntr = Point(static_cast<int>(pca_analysis.mean.at<double>(0, 0)),
static_cast<int>(pca_analysis.mean.at<double>(0, 1)));
//Store the eigenvalues and eigenvectors
vector<Point2d> eigen_vecs(2);
vector<double> eigen_val(2);
*for (int i = 0; i < 2; ++i)
{
eigen_vecs[i] = Point2d(pca_analysis.eigenvectors.at<double>(i, 0),
pca_analysis.eigenvectors.at<double>(i, 1));
eigen_val[i] = pca_analysis.eigenvalues.at<double>(0, i);
}*
// Draw the principal components
circle(img, cntr, 3, Scalar(255, 0, 255), 2);
Point p1 = cntr + 0.02 * Point(static_cast<int>(eigen_vecs[0].x * eigen_val[0]), static_cast<int>(eigen_vecs[0].y * eigen_val[0]));
Point p2 = cntr - 0.02 * Point(static_cast<int>(eigen_vecs[1].x * eigen_val[1]), static_cast<int>(eigen_vecs[1].y * eigen_val[1]));
drawAxis(img, cntr, p1, Scalar(0, 255, 0), 1);
drawAxis(img, cntr, p2, Scalar(255, 255, 0), 5);
double angle = atan2(eigen_vecs[0].y, eigen_vecs[0].x); // orientation in radians
return angle;
}
int main(int, char** argv)
{
// Load image
Mat src = imread("C:/Users/aydin/Desktop/c++/pictures/pca_test1.jpg");
//Mat src = imread(argv[1]);
// Check if image is loaded successfully
if (!src.data || src.empty())
{
cout << "Problem loading image!!!" << endl;
return EXIT_FAILURE;
}
imshow("src", src);
// Convert image to grayscale
Mat gray;
cvtColor(src, gray, COLOR_BGR2GRAY);
// Convert image to binary
Mat bw;
threshold(gray, bw, 50, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);
// Find all the contours in the thresholded image
vector<Vec4i> hierarchy;
vector<vector<Point> > contours;
findContours(bw, contours, hierarchy, CV_RETR_LIST, CV_CHAIN_APPROX_NONE);
for (size_t i = 0; i < contours.size(); ++i)
{
// Calculate the area of each contour
double area = contourArea(contours[i]);
// Ignore contours that are too small or too large
if (area < 1e2 || 1e5 < area) continue;
// Draw each contour only for visualisation purposes
drawContours(src, contours, static_cast<int>(i), Scalar(0, 0, 255), 2, 8, hierarchy, 0);
// Find the orientation of each shape
//getOrientation(contours[i], src);
}
imshow("output", src);
waitKey(0);
return 0;
}
不,这与环境无关;I不知道,你是如何让它工作的,但后来我在这里看到了同样的错误,他放了正确的代码说它有错误.但是将此代码与原始代码进行比较,我发现在我提到的"for loop"中有问题
for (int i = 0; i < 2; ++i)
{
eigen_vecs[i] = Point2d(pca_analysis.eigenvectors.at<double>(i, 0),
pca_analysis.eigenvectors.at<double>(i, 1));
eigen_val[i] = pca_analysis.eigenvalues.at<double>(0,i);
}
,他将最后一个偏执从(0,i)改为(i)。 我做了同样的事情并且它有效,但我不明白为什么,你能告诉我为什么吗?
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